TC646BEPA

TC646BEPA MICROCHIP | Alldatasheet

Document overview

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Technical content

Features

• T emperature-Proportional Fan Speed for Acoustic Noise Reduction and Longer Fan Life
• Efficient PWM Fan Drive
• 3.0V to 5.5V Supply Range: - Fan Voltage Independent of TC646B/ TC648B/TC649B Supply Voltage - Supports any Fan Voltage
• FanSense ™ Fault Detection Circuit Protects Against Fan Failure and Aids System Testing (TC646B/TC649B)
• Automatic Shutdown Mode for “Green” Systems
• Supports Low Cost NTC/PTC Thermistors
• Over-Temperature Indication (TC646B/TC648B)
• Fan Auto-Restart
• Space-Saving 8-Pin MSOP Package

Applications

• Personal Computers & Servers
• LCD Projectors
• Datacom & Telecom Equipment
• Fan Trays
• File Servers
• General-Purpose Fan Speed Control Package Types

Description

The TC646B/TC648B/TC649B devices are new ver- sions of the existing TC646/TC648/TC649 fan speed controllers. These devices are switch-mode fan speed controllers that incorporate a new fan auto-restart func- tion. Temperature-proportional speed control is accom- plished using pulse width modulation. A thermistor (or other voltage output temperature sensor) connected to the V IN input supplies the required control voltage of 1.20V to 2.60V (typical) for 0% to 100% PWM duty cycle. The auto-shutdown threshold/temperature is set by a simple resistor divider on the V AS input. An inte- grated Start-Up Timer ensures reliable fan motor start- up at turn-on, coming out of shutdown mode, auto- shutdown mode or following a transient fault. A logic low applied to V IN (pin 1) causes fan shutdown. The TC646B and TC649B also feature Microchip Technology's proprietary FanSense technology for increasing system reliability. In normal fan operation, a pulse train is present at SENSE (pin 5). A missing- pulse detector monitors this pin during fan operation. A stalled, open or unconnected fan causes the TC646B/ TC649B device to turn the V OUT output on full (100% duty cycle). If the fan fault persists (a fan current pulse is not detected within a 32/f period), the FAULT output goes low. Even with the FAULT output low, the V OUT output is on full during the fan fault condition in order to attempt to restart the fan. FAULT (TC646B) or OTF (TC648B) is also asserted if the PWM reaches 100% duty cycle, indicating that maximum cooling capability has been reached and a possible overheating condition exists. The TC646B, TC648B and TC649B devices are avail- able in 8-pin plastic MSOP , SOIC and PDIP packages. The specified temperature range of these devices is -40 to +85ºC. MSOP, PDIP, SOIC VDD V OUT SENSE VIN CF VAS GND FAULT TC646B TC649B VDD V OUT NC VIN CF VAS GND OTFTC648B PWM Fan Speed Controllers With Auto-Shutdown, Fan Restart and FanSense™ Technology for Fault Detection

DS21755B-page 2  2003 Microchip Technology Inc. Functional Block Diagram TC646B/TC649B Note: The VOTF comparator is for the TC646B device only. 70 mV (typ) VOTF 10 kΩ VSHDN VIN CF VAS GND VDD VOUT FAULT SENSE Clock Generator Control Logic 3xTPWM Timer Start-up Timer Missing Pulse Detect TC648B VOTF VSHDN VIN CF VAS GND VDD VOUT OTF NC Clock Generator Control Logic Start-up Timer Note

 2003 Microchip Technology Inc. DS21755B-page 3 TC646B/TC648B/TC649B

1.0 ELECTRICAL

Absolute Maximum Ratings† † Notice: Stresses above those listed under “Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operational listings of this specification is not implied. Expo- sure to maximum rating conditions for extended periods may affect device reliability. PIN FUNCTION TABLE Name Function VIN Analog Input CF Analog Output VAS Analog Input GND Ground SENSE/NC Analog Input. No Connect (NC) for TC648B FAULT/OTF Digital (Open-Drain) Output OTF for TC648B VOUT Digital Output VDD Power Supply Input

ELECTRICAL CHARACTERISTICS

Electrical Specifications: Unless otherwise specified, all limits are specified for -40°C < T A < +85°C, VDD = 3.0V to 5.5V. Parameters Sym Min Typ Max Units Conditions Supply Voltage V DD 3.0 — 5.5 V Supply Current, Operating I DD — 200 400 µA Pins 6, 7 Open, CF = 1 µF, VIN = VC(MAX) Supply Current, Shutdown Mode I DD(SHDN) — 30 — µA Pins 6, 7 Open, CF = 1 µF, VIN = 0.35V VOUT Output Sink Current at VOUT Output I OL 1.0 — — mA V OL = 10% of VDD Source Current at VOUT Output I OH 5.0 — — mA V OH = 80% of VDD VIN, VAS Inputs Input Voltage at VIN for 100% PWM Duty Cycle VC(MAX) 2.45 2.60 2.75 V Over-Temperature Indication Threshold VOTF VC(MAX) + 20 mV V For TC646B and TC648B Over-Temperature Indication Threshold Hysteresis VOTF-HYS 80 mV For TC646B and TC648B VC(MAX) - VC(MIN) VC(SPAN) 1.3 1.4 1.5 V Hysteresis on Auto-Shutdown Comparator VHAS —7 0 — m V Auto-Shutdown Threshold V AS VC(MAX) - VC(SPAN) —V C(MAX) V Voltage Applied to VIN to Ensure Shutdown Mode VSHDN —— V DD x 0.13 V Voltage Applied to VIN to Release Shutdown Mode VREL VDD x 0.19 — — V V DD = 5V Hysteresis on VSHDN, VREL VHYST —0 . 0 3 X VDD VIN, VAS Input Leakage I IN - 1.0 — +1.0 µA Note 1 Note 1: Ensured by design, tested during characterization. 2: For VDD < 3.7V, tSTARTUP and tMP timers are typically 13/f.

DS21755B-page 4  2003 Microchip Technology Inc. TEMPERATURE SPECIFICATIONS Pulse-Width Modulator PWM Frequency f PWM 26 30 34 Hz C F = 1.0 µF SENSE Input (TC646B & TC649B) SENSE Input Threshold Voltage with Respect to GND VTH(SENSE) 50 70 90 mV Blanking time to ignore pulse due to VOUT turn-on tBLANK —3 . 0— µ s e c FAULT / OTF Output Output Low Voltage V OL —— 0 . 3 V I OL = 2.5 mA Missing Pulse Detector Timer t MP — 32/f — sec TC646B and TC649B, Note 2 Start-up Timer t STARTUP —3 2 / f — s e c Note 2 Diagnostic Timer t DIAG — 3/f — sec TC646B and TC649B ELECTRICAL CHARACTERISTICS (CONTINUED) Electrical Specifications: Unless otherwise specified, all limits are specified for -40°C < T A < +85°C, VDD = 3.0V to 5.5V. Parameters Sym Min Typ Max Units Conditions Note 1: Ensured by design, tested during characterization. 2: For VDD < 3.7V, tSTARTUP and tMP timers are typically 13/f. Electrical Characteristics: Unless otherwise noted, all parameters apply at V DD = 3.0V to 5.5V Parameters Sym Min Typ Max Units Conditions Temperature Ranges Specified Temperature Range T A -40 — +85 °C Operating Temperature Range T A -40 — +125 °C Storage Temperature Range T A -65 — +150 °C Thermal Package Resistances Thermal Package Resistance, 8-Pin MSOP θ JA —2 0 0— ° C / W Thermal Package Resistance, 8-Pin SOIC θJA —1 5 5— ° C / W Thermal Package Resistance, 8-Pin PDIP θJA —1 2 5— ° C / W

DS21755B-page 6  2003 Microchip Technology Inc. FIGURE 1-4: TC646B/TC648B/TC649B Electrical Characteristics Test Circuit. VIN CF VAS GND FAULT / OTF SENSE VOUT VDD 0.1 µF 1µ F VDD 0.1 µF + VIN+ 0.1 µFVAS+ K1 K2 0.1 µF1µ F.01 µF C7 C6 C5 VSENSE (pulse voltage source) Current limited voltage source VDD Current limited voltage source 0.1 µF Note: C5 and C7 are adjusted to get the necessary 1 µF value. TC646B and TC649B TC646B TC648B TC649B

 2003 Microchip Technology Inc. DS21755B-page 7 TC646B/TC648B/TC649B

2.0 TYPICAL PERFORMANCE CURVES

Note: Unless otherwise indicated, V DD = 5V, TA = 25°C. FIGURE 2-1: IDD vs. Temperature. FIGURE 2-2: PWM Sink Current (I OL) vs. VOL. FIGURE 2-3: PWM Source Current (I OH) vs. VDD - VOH. FIGURE 2-4: PWM Frequency vs. Temperature. FIGURE 2-5: IDD vs. VDD. FIGURE 2-6: IDD Shutdown vs. Temperature. Note: The graphs and tables provided following this note are a statistical summary based on a limited number of samples and are provided for informational purposes only. The performance characteristics listed herein are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified operating range (e.g., outside specified power supply range) and therefore outside the warranted range. 125 130 135 140 145 150 155 160 165 -40 -25 -10 5 20 35 50 65 80 95 110 125 Temperature (ºC) IDD (µA) VDD = 3.0V VDD = 5.5V Pins 6 & 7 Open CF = 1 µF 0 50 100 150 200 250 300 350 400 450 500 550 600 VOL (mV) IOL (mA) VDD = 5.5V VDD = 5.0V VDD = 3.0V VDD = 4.0V 0 100 200 300 400 500 600 700 800 VDD - VOH (mV) IOH (mA) VDD = 5.5V VDD = 5.0V VDD = 3.0V VDD = 4.0V 28.50 29.00 29.50 30.00 30.50 -40 -25 -10 5 20 35 50 65 80 95 110 125 Temperature (ºC) Oscillator Frequency (Hz) VDD = 3.0V VDD = 5.5V CF = 1.0PF 125 130 135 140 145 150 155 160 165 170 33 . 544 . 555 . 5 VDD (V) IDD (µA) TA = -40ºC TA = -5ºC TA = +125ºC TA = +90ºC Pins 6 & 7 Open CF = 1 µF -40 -25 -10 5 20 35 50 65 80 95 110 125 Temperature (ºC) IDD Shutdown (µA) VDD = 5.5V VDD = 3.0V Pins 6 & 7 Open VIN = 0V

DS21755B-page 10  2003 Microchip Technology Inc.

3.0 PIN FUNCTIONS

The descriptions of the pins are given in T able 3-1. TABLE 3-1: PIN FUNCTION TABLE

3.1 Analog Input (V IN)

The thermistor network (or other temperature sensor) connects to VIN. A voltage range of 1.20V to 2.60V (typ- ical) on this pin drives an active duty cycle of 0% to 100% on the V OUT pin. The TC646B, TC648B and TC649B devices enter shutdown mode when 0 ≤ V IN ≤ VSHDN. During shutdown, the FAULT /OTF output is inactive and supply current falls to 30 µA (typical).

3.2 Analog Output (C F)

CF is the positive terminal for the PWM ramp generator timing capacitor. The recommended value for the C F capacitor is 1.0 µF for 30 Hz PWM operation.

3.3 Analog Input (V AS)

An external resistor divider connected to V AS sets the auto-shutdown threshold. Auto-shutdown occurs when V IN < V AS. The fan is automatically restarted when VIN > (V AS + V HAS). During auto-shutdown, the FAULT/OTF output is inactive and supply current falls to 30 µA (typical).

3.4 Analog Input (SENSE)

Pulses are detected at SENSE as fan rotation chops the current through a sense resistor. The absence of pulses indicates a fan fault condition.

3.5 Digital (Open-Drain) Output

(FAULT/OTF) FAULT/OTF goes low to indicate a fault condition. When FAULT goes low due to a fan fault (TC646B and TC649B devices), the output will remain low until the fan fault condition has been removed (16 pulses have been detected at the SENSE pin in a 32/f period). For the TC646B and TC648B devices, the FAULT /OTF out- put will also be asserted when the V IN voltage reaches the V OTF threshold of 2.62V (typical). This gives an over-temperature/100% fan speed indication .

3.6 Digital Output (V OUT)

VOUT is an active-high complimentary output that drives the base of an external NPN transistor (via an appropriate base resistor) or the gate of an N-channel MOSFET. This output has asymmetrical drive. During a fan fault condition, the V OUT output is continuously on.

3.7 Power Supply Input (V DD)

The VDD pin with respect to GND provides power to the device. This bias supply voltage may be independent of the fan power supply.

3.8 Ground (GND)

Ground terminal.

3.9 No Connect (NC)

No internal connection. Pin Name Function 1V IN Analog Input 2C F Analog Output 3V AS Analog Input

4 GND Ground

5 SENSE/NC Analog Input/No Connect. NC for TC648B. 6F A U L T /OTF Digital (Open-Drain) Output OTF for TC648B 7V OUT Digital Output 8V DD Power Supply Input

 2003 Microchip Technology Inc. DS21755B-page 11 TC646B/TC648B/TC649B

4.0 DEVICE OPERATION

The TC646B/TC648B/TC649B devices are a family of temperature-proportional, PWM mode, fan speed con- trollers. Features of the family include minimum fan speed, fan auto-shutdown, fan auto-restart, remote shutdown, over-temperature indication and fan fault detection. The TC64XB family is slightly different from the original TC64X family, which includes the TC642, TC646, TC647, TC648 and TC649 devices. Changes have been made to adjust the operation of the device during a fan fault condition. The key change to the TC64XB family of devices (TC642B, TC647B, TC646B, TC648B, TC649B) is that the FAULT and V OUT outputs no longer “latch” to a state during a fan fault condition. The TC646B/ TC648B/TC649B family will continue to monitor the operation of the fan so that when the fan returns to nor- mal operation, the fan speed controller will also return to normal operation (PWM mode). The operation and features of these devices are discussed in the following sections.

4.1 Fan Speed Control Methods

The speed of a DC brushless fan is proportional to the voltage across it. This relationship will vary from fan-to- fan and should be characterized on an individual basis. The speed versus applied voltage relationship can then be used to set up the fan speed control algorithm. There are two main methods for fan speed control. The first is pulse width modulation (PWM) and the second is linear. Using either method, the total system power requirement to run the fan is equal. The difference between the two methods is where the power is consumed. The following example compares the two methods for a 12V, 120 mA fan running at 50% speed. With 6V applied across the fan, the fan draws an average current of 68 mA. Using a linear control method, there is 6V across the fan and 6V across the drive element. With 6V and 68 mA, the drive element is dissipating 410 mW of power. Using the PWM approach, the fan voltage is modulated at a 50% duty cycle, with most of the 12V being dropped across the fan. With 50% duty cycle, the fan draws a RMS current of 110 mA and an average cur- rent of 72 mA. Using a MOSFET with a 1 Ω R DS(on) (a fairly typical value for this low current), the power dissi- pation in the drive element would be: 12 mW (Irms 2 * RDS(on)). Using a standard 2N2222A NPN transistor (assuming a Vce-sat of 0.8V), the power dissipation would be 58 mW (Iavg* Vce-sat). The PWM approach to fan speed control results in much less power dissipation in the drive element. This allows smaller devices to be used and will not require special heatsinking to remove the power being dissipated in the package. The other advantage of the PWM approach is that the voltage being applied to the fan is always near 12V. This eliminates any concern about not supplying a high enough voltage to run the internal fan components, which is very relevant in linear fan speed control.

4.2 PWM Fan Speed Control

The TC646B, TC648B and TC649B devices implement PWM fan speed control by varying the duty cycle of a fixed-frequency pulse train. The duty cycle of a wave- form is the on time divided by the total period of the pulse. For example, if we take a 100 Hz waveform (10 ms) with an on time of 5.0 ms, the duty cycle of this waveform is 50% (5.0 ms / 10.0 ms). This example is shown in Figure 4-1. FIGURE 4-1: Duty Cycle of a PWM Waveform. The TC646B/TC648B/TC649B devices generate a pulse train with a typical frequency of 30 Hz F = 1 µF). The duty cycle can be varied from 0% to 100%. The pulse train generated by the TC646B/ TC648B/TC649B device drives the gate of an external N-channel MOSFET or the base of an NPN transistor. (shown in Figure 4-2). See Section 5.5, “Output Drive Device Selection”, for more information on output drive device selection. t ton toff t = Period t = 1/f f = Frequency D = Duty Cycle D = ton / t

DS21755B-page 12  2003 Microchip Technology Inc. FIGURE 4-2: PWM Fan Drive. By modulating the voltage applied to the gate of the MOSFET (Q DRIVE), the voltage that is applied to the fan is also modulated. When the VOUT pulse is high, the gate of the MOSFET is turned on, pulling the voltage at the drain of Q DRIVE to zero volts. This places the full 12V across the fan for the ton period of the pulse. When the duty cycle of the drive pulse is 100% (full on, ton = t), the fan will run at full speed. As the duty cycle is decreased (pulse on time “t on” is lowered), the fan will slow down proportionally. With the TC646B, TC648B and TC649B devices, the duty cycle is con- trolled by the V IN input and can also be terminated by the V AS input (auto-shutdown). This is described in more detail in Section 5.5, “Output Drive Device Selection”.

4.3 Fan Start-up

Often overlooked in fan speed control is the actual start-up control period. When starting a fan from a non- operating condition (fan speed is zero revolutions per minute (RPM)), the desired PWM duty cycle or average fan voltage cannot be applied immediately. Since the fan is at a rest position, the fan’s inertia must be over- come to get it started. The best way to accomplish this is to apply the full rated voltage to the fan for a minimum of one second. This will ensure that in all operating environments, the fan will start and operate properly. An example of the start-up timing is shown in Figure 1-1. A key feature of the TC646B/TC648B/TC649B devices is the start-up timer. When power is first applied to the device, or when the device is brought out of the shut- down/auto-shutdown modes of operation, the V OUT output will go to a high state for 32 PWM cycles (one second for C F = 1 µF). This will drive the fan to full speed for this time frame. During the start-up period for the TC646B and TC649B devices, the SENSE pin is being monitored for fan pulses. If pulses are detected during this period, the fan speed controller will then move to PWM operation. If pulses are not detected during the start-up period, the start-up timer is activated again. If pulses are not detected at the SENSE pin during this additional period, the FAULT output will go low to indicate that a fan fault condition has occurred. See Section 4.7, “FAULT/OTF Output”, for more details.

4.4 PWM Frequency & Duty Cycle

Control (CF & VIN Pins) The frequency of the PWM pulse train is controlled by the CF pin. By attaching a capacitor to the C F pin, the frequency of the PWM pulse train can be set to the desired value. The typical PWM frequency for a 1.0 µF capacitor is 30 Hz. The frequency can be adjusted by raising or lowering the value of the capacitor. The C F pin functions as a ramp generator. The voltage at this pin will ramp from 1.20V to 2.60V (typically) as a saw- tooth waveform. An example of this is shown in Figure 4-3. FIGURE 4-3: CF Pin Voltage. The duty cycle of the PWM output is controlled by the voltage at the VIN input pin. The duty cycle of the PWM output is produced by comparing the voltage at the VIN pin to the voltage ramp at the CF pin. When the voltage at the VIN pin is 1.20V, the duty cycle will be 0%. When the voltage at the VIN pin is 2.60V, the PWM duty cycle will be 100% (these are both typical values). The VIN-to-PWM duty cycle relationship is shown in Figure 4-4. The lower value of 1.20V is referred to as “V CMIN” and the 2.60V threshold is referred to as “VCMAX”. A calcu- lation for duty cycle is shown in the equation below. The voltage range between VCMIN and VCMAX is character- ized as “VCSPAN“ and has a typical value of 1.4V, with minimum and maximum values of 1.3V and 1.5V, respectively. EQUATION PWM DUTY CYCLE FAN 12V QDRIVETC646B TC648B TC649B VDD GND VOUT G D S 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 0 2 04 06 08 0 1 0 0 Time (msec) CF Voltage (V) CF = 1 µF VCMAX VCMIN Duty Cycle (%) = VCMAX - VCMIN (VIN - VCMIN) * 100

 2003 Microchip Technology Inc. DS21755B-page 13 TC646B/TC648B/TC649B For the TC646B, TC648B and TC649B devices, the VIN pin is also used as the shutdown pin. The V SHDN and VREL threshold voltages are characterized in the “Elec- trical Characteristics Table” of Section 1.0. If the VIN pin voltage is pulled below the VSHDN threshold, the device will shut down (V OUT output goes to a low state, the FAULT/OTF pin is inactive). If the voltage on the VIN pin then rises above the release threshold (V REL), the device will go through a power-up sequence (assuming that the V IN voltage is also higher than the voltage at the VAS pin). The power-up sequence is shown later in the “Behavioral Algorithm Flowcharts” of Section 4.9. FIGURE 4-4: VIN Voltage vs. PWM Duty Cycle (Typical).

4.5 Auto-Shutdown Mode (V AS)

For the TC646B, TC648B and TC649B devices, pin 3 is the VAS pin and is used for setting the auto-shutdown threshold voltage. The auto-shutdown function provides a way to set a threshold voltage (temperature) at which the fan will be shut off. This way, if the temperature in the system reaches a threshold at which the fan(s) no longer needs to operate, the fan can be shutdown automatically. The voltage range for the V AS pin is the same as the voltage range for the VIN pin (1.20V to 2.60V). The volt- age at the VAS pin is set in this range so that when the voltage at the V IN pin decreases below the voltage at the VAS pin (signifying that the threshold temperature has been reached), the VOUT output is shut off (goes to a low state). In auto-shutdown, the FAULT /OTF output is inactive (high-impedance). Auto-shutdown mode is exited when the V IN voltage exceeds the V AS voltage by the auto-shutdown hysteresis voltage (V HAS). Upon exiting auto-shutdown mode, the start-up timer is triggered and the device returns to normal operation.

4.6 V OUT Output (PWM Output)

The VOUT output is a digital output designed for driving the base of a transistor or the gate of a MOSFET. The V OUT output is designed to be able to quickly raise the base current or the gate voltage of the external drive device to its final value. When the device is in shutdown/auto-shutdown mode, the V OUT output is actively held low. The output can be varied from 0% (full off) to 100% duty cycle (full on). As previously discussed, the duty cycle of the VOUT output is controlled via the VIN input voltage and can be termi- nated based on the VAS voltage. A base current-limiting resistor is required when using a transistor as the external drive device in order to limit the amount of drive current that is drawn from the VOUT output. The VOUT output can be directly connected to the gate of an external MOSFET . One concern when doing this, though, is that the fast turn-off time of the fan drive MOSFET can cause a problem because the fan motor looks like an inductor. When the MOSFET is turned off quickly, the current in the fan wants to continue to flow in the same direction. This causes the voltage at the drain of the MOSFET to rise. If there aren’t any clamp diodes internal to the fan, this voltage can rise above the drain-to-source voltage rating of the MOSFET . For this reason, an external clamp diode is suggested. This is shown in Figure 4-5. FIGURE 4-5: Clamp Diode for Fan.

4.7 FAULT /OTF Output

The FAULT/OTF output is an open-drain, active-low output. For the TC646B and TC649B devices, pin 6 is labeled as the FAULT output and indicates when a fan fault condition has occurred. For the TC646B device, the FAULT output also indicates when an over-temper- ature (OTF) condition has occurred. For the TC648B device, pin 6 is the OTF output that indicates an over- temperature (OTF) condition has occurred. 100 VIN (V) Duty Cycle (%) GND RSENSE VOUT Q1: N-Channel MOSFET FAN Clamp Diode

DS21755B-page 14  2003 Microchip Technology Inc. For the TC646B and TC648B devices, an over-temper- ature condition is indicated when the VIN input reaches the VOTF threshold voltage (the VOTF threshold voltage is typically 20 mV higher than the VCMAX threshold and has 80 mV of hysteresis). This indicates that maximum cooling capacity has been reached (the fan is at full speed) and that an overheating situation can occur. When the voltage at the V IN input falls below the V OTF threshold voltage by the hysteresis value (V OTF-HYS), the FAULT/OTF output will return to the high state (a pull-up resistor is needed on the FAULT/OTF output). For the TC646B/TC649B devices, a fan fault condition is indicated when fan current pulses are no longer detected at the SENSE pin. Pulses at the SENSE pin indicate that the fan is spinning and conducting current. If pulses are not detected at the SENSE pin for 32 PWM cycles, the 3-cycle diagnostic timer is fired. This means that the V OUT output is high for 3 PWM cycles. If pulses are detected in this 3-cycle period, nor- mal PWM operation is resumed and no fan fault is indi- cated. If no pulses are detected in the 3-cycle period, the start-up timer is activated and the V OUT output is driven high for 32 PWM cycles. If pulses are detected during this time-frame, normal PWM operation is resumed. If no pulses are detected during this time- period, a fan fault condition exists and the FAULT output is pulled low. During a fan fault condition, the FAULT output will remain low until the fault condition has been removed. During this time, the V OUT output is driven high contin- uously to attempt to restart the fan and the SENSE pin is monitored for fan pulses. If a minimum of 16 pulses are detected at the SENSE input over a 32 cycle time- period (one second for C F = 1.0 µF), the fan fault con- dition no longer exists. Therefore, The FAULT output is released and the V OUT output returns to normal PWM operation, as dictated by the V IN and VAS inputs. If the VIN voltage is pulled below the VSHDN level during a fan fault condition, the FAULT output will be released and the V OUT output will be shutdown (V OUT = 0V). If the VIN voltage then increases above the V REL thresh- old and is above the V AS voltage, the device will go through the normal start-up routine. If, during a fan fault condition, the voltage at the VIN pin drops below the V AS voltage level, the TC646B/ TC649B device will continue to hold the FAULT line low and drive the VOUT output to 100% duty cycle. If the fan fault condition is then removed, the FAULT output will be released and the TC646B/TC649B device will enter auto-shutdown mode until the V IN voltage is brought above the VAS voltage by the auto-shutdown hysteresis value (V HAS). The TC646B/TC649B device will then resume normal PWM mode operation. The sink current capability of the FAULT output is listed in the “Electrical Characteristics Table” of Section 1.0.

4.8 Sensing Fan Operation (SENSE)

The SENSE input is an analog input used to monitor the fan’s operation (the TC648B device does not incor- porate the fan sensing feature). It does this by sensing fan current pulses that represent fan rotation. When a fan rotates, commutation of the fan current occurs as the fan poles pass the armatures of the motor. The commutation of the fan current makes the current waveshape appear as pulses. There are two typical current waveforms of brushless DC fan motors, illustrated in Figures 4-6 and 4-7. FIGURE 4-6: Fan Current With DC Offset And Positive Commutation Current. FIGURE 4-7: Fan Current With Commutation Pulses To Zero.

 2003 Microchip Technology Inc. DS21755B-page 15 TC646B/TC648B/TC649B The SENSE pin senses positive voltage pulses that have an amplitude of 70 mV (typical value). Each time a pulse is detected, the missing pulse detector timer MP) is reset. As previously stated, if the missing pulse detector timer reaches the time for 32 cycles, the loop for diagnosing a fan fault is engaged (diagnostic timer, then the start-up timer). Both of the fan current waveshapes shown in Figures 4-6 and 4-7 can be sensed with the sensing scheme shown in Figure 4-8. FIGURE 4-8: Sensing Scheme For Fan Current. The fan current flowing through R SENSE generates a voltage that is proportional to the current. The C SENSE capacitor removes any DC portion of the voltage across R SENSE and presents only the voltage pulse portion to the SENSE pin of the TC646B/TC649B devices. The RSENSE and CSENSE values need to be selected so that the voltage pulse provided to the SENSE pin is 70 mV (typical) in amplitude. Be sure to check the sense pulse amplitude over all operating conditions (duty cycles) as the current pulse amplitude will vary with duty cycle. See Section 5.0, “Applications Informa- tion”, for more details on selecting values for R SENSE and CSENSE. Key features of the SENSE pin circuitry are an initial blanking period after every V OUT pulse and an initial pulse blanker. The TC646B/TC649B sense circuitry has a blanking period that occurs at the turn-on of each V OUT pulse. During this blanking period, the sense circuitry ignores any pulse information that is seen at the SENSE pin input. This stops the TC646B/TC649B device from falsely sensing a current pulse that is due to the fan drive device turn-on. The initial pulse blanker is also implemented to stop false sensing of fan current pulses. When a fan is in a locked rotor condition, the fan current no longer com- mutates, it simply flows through one fan winding and is a DC current. When a fan is in a locked rotor condition and the TC646B/TC649B device is in PWM mode, it will see one current pulse each time the V OUT output is turned on. The initial pulse blanker allows the TC646B/TC649B device to ignore this pulse and recognize that the fan is in a fault condition.

4.9 Behavioral Algorithms

The behavioral algorithms for the TC646B/TC649B and TC648B devices are shown in Figure 4-9 and Figure 4-10, respectively. The behavioral algorithms show the step-by-step deci- sion-making process for the fan speed controller oper- ation. The TC646B and TC649B devices are very similar with one exception: the TC649B device does not implement the over-temperature portion of the algorithm. RISO RSENSE CSENSE (0.1 µF typical) SENSE VOUT TC64XB GND FAN

DS21755B-page 16  2003 Microchip Technology Inc. FIGURE 4-9: TC646B/TC649B Behavioral Algorithm. Fire Start-up Timer (1 sec) Fan Pulse Detected? Fan Pulse Detected? VIN < VSHDN? VIN < VAS? Shutdown VOUT = 0 Auto- Shutdown VOUT = 0 Yes No No No No Yes Yes Yes Power-Up Normal Operation Fan Fault Power-on Reset FAULT = 1 VIN > VREL? No VIN> (VAS+ VHAS) Yes Yes No Hot Start Fire Start-up Timer (1 sec) Fire Start-up Timer (1 sec) VIN > VREL? Yes Fan Fault Clear Missing Pulse Detector VOUT Proportional to VIN VIN < VSHDN? VIN < VAS? VIN > VOTF? M.P.D. Expired? Fan Pulse Detected? Shutdown VOUT = 0 Auto Shutdown V OUT = 0 No No No No No No Yes YesYe s Yes Normal Operation Power-Up VIN > (VAS + VHAS) No Yes Hot Start Yes No FAULT = 0 Yes Fire Diagnostic Timer (100 msec) Fan Pulse Detected? Fan Pulse Detected? Yes No FAULT = Low, VOUT = High

16 Pulses

Detected? No Yes Power-Up VIN< VSHDN? VIN > VREL? Fan Fault Yes Normal Operation Shutdown VOUT = 0 Yes No No TC646B Only

 2003 Microchip Technology Inc. DS21755B-page 17 TC646B/TC648B/TC649B FIGURE 4-10: TC648B Behavioral Algorithm. VAS = 0V VIN < VAS? Auto- Shutdown VOUT = 0 Yes No No Ye s Power-Up Power-on Reset OTF = 1 VIN > (VAS+ VHAS) Yes No Fire Start-up Timer (1 sec) VIN > 1.20V VOUT Proportional to VIN VIN > VOTF? Auto Shutdown VOUT = 0 No No Yes Normal Operation VOUT = 0 No Yes Yes Minimum Speed Mode Normal Operation OTF = 1OTF = 0 VIN < VAS? Minimum Speed Mode VIN = 0V Power-Up VIN > 1.20V VOUT Proportional to VIN VIN > VOTF? No Yes OTF = 1OTF = 0 VOUT = 0 Yes No No Ye s

DS21755B-page 18  2003 Microchip Technology Inc.

5.0 APPLICATIONS INFORMATION

5.1 Setting the PWM Frequency

The PWM frequency of the V OUT output is set by the capacitor value attached to the C F pin. The PWM fre- quency will be 30 Hz (typical) for a 1 µF capacitor. The relationship between frequency and capacitor value is linear, making alternate frequency selections easy. As stated in previous sections, the PWM frequency should be kept in the range of 15 Hz to 35 Hz. This will eliminate the possibility of having audible frequencies when varying the duty cycle of the fan drive. A very important factor to consider when selecting the PWM frequency for the TC646B/TC648B/TC649B devices is the RPM rating of the selected fan and the minimum duty cycle that you will be operating at. For fans that have a full-speed rating of 3000 RPM or less, it is desirable to use a lower PWM frequency. A lower PWM frequency allows for a longer time-period to mon- itor the fan current pulses. The goal is to be able to monitor at least two fan current pulses during the on- time of the V OUT output. Example: The system design requirement is to operate the fan at 50% duty cycle when ambient temperatures are below 20°C. The fan full-speed RPM rating is 3000 RPM and has four current pulses per rotation. At 50% duty cycle, the fan will be operating at approximately 1500 RPM. EQUATION If one fan revolution occurs in 40 msec, each fan pulse occurs 10 msec apart. In order to detect two fan current pulses, the on-time of the V OUT pulse must be at least 20 msec. With the duty cycle at 50%, the total period of one cycle must be at least 40 msec, which makes the PWM frequency 25 Hz. For this example, a PWM fre- quency of 20 Hz is recommended. This would define a C F capacitor value of 1.5 µF.

5.2 Temperature Sensor Design

As discussed in previous sections, the VIN analog input has a range of 1.20V to 2.60V (typical), which repre- sents a duty cycle range on the V OUT output of 0% to 100%, respectively. The VIN voltages can be thought of as representing temperatures. The 1.20V level is the low temperature at which the system requires very little cooling. The 2.60V level is the high temperature, for which the system needs maximum cooling capability (100% fan speed). One of the simplest ways of sensing temperature over a given range is to use a thermistor. By using a NTC thermistor, as shown in Figure 5-1, a temperature- variant voltage can be created. FIGURE 5-1: Temperature Sensing Circuit. Figure 5-1 represents a temperature-dependent, volt- age divider circuit. RT is a conventional NTC thermistor, R1 and R 2 are standard resistors. R 1 and R T form a parallel resistor combination that will be referred to as RTEMP (RTEMP = R1 * RT / R1 + RT). As the temperature increases, the value of R T decreases and the value of RTEMP will decrease with it. Accordingly, the voltage at VIN increases as temperature increases, giving the desired relationship for the VIN input. R1 helps to linear- ize the response of the SENSE network and aids in obtaining the proper VIN voltages over the desired tem- perature range. An example of this is shown in Figure 5-2. If less current draw from V DD is desired, a larger value thermistor should be chosen. The voltage at the VIN pin can also be generated by a voltage output temperature sensor device. The key is to get the desired V IN volt- age-to-system (or component) temperature relation- ship. The following equations apply to the circuit in Figure 5-1. EQUATION In order to solve for the values of R 1, R2, VIN and the temperatures at which they are to occur, need to be selected. The variables T1 and T2 represent the selected temperatures. The value of the thermistor at these two temperatures can be found in the thermistor Time for one revolution (msec.) 60 1000× R1RT IDIV VIN VDD VT 1() VDD R2× VT 2() VDD R2×

 2003 Microchip Technology Inc. DS21755B-page 19 TC646B/TC648B/TC649B data sheet. With the values for the thermistor and the values for VIN, you now have two equations from which the values for R1 and R2 can be found. Example: The following design goals are desired:

• Duty Cycle = 50% (V IN = 1.90V) with T emperature (T1) = 30°C
• Duty Cycle = 100% (V IN = 2.60V) with T emperature (T2) = 60°C Using a 100 kΩ thermistor (25°C value), we look up the thermistor values at the desired temperatures:
• R T (T1) = 79428Ω @ 30°C
• R T (T2) = 22593Ω @ 60°C Substituting these numbers into the given equations produces the following numbers for R 1 and R2.
• R 1 = 34.8 kΩ
• R 2 = 14.7 kΩ FIGURE 5-2: How Thermistor Resistance, VIN, and RTEMP Vary With Temperature. Figure 5-2 graphs R T, R TEMP (R 1 in parallel with R T) and V IN, versus temperature for the example shown above.

5.3 Thermistor Selection

As with any component, there are a number of sources for thermistors. A listing of companies that manufacture thermistors can be found at www.temperatures.com/ thermivendors.html. This website lists over forty suppliers of thermistor products. A brief list is shown here:

5.4 FanSense Network

(RSENSE and CSENSE) The SENSE network (comprised of R SENSE and CSENSE) allows the TC646B and TC649B devices to detect commutation of the fan motor. R SENSE converts the fan current into a voltage. C SENSE AC couples this voltage signal to the SENSE pin. The goal of the SENSE network is to provide a voltage pulse to the SENSE pin that has a minimum amplitude of 90 mV. This will ensure that the current pulse caused by the fan commutation is recognized by the TC646B/ TC649B device. A 0.1 µF ceramic capacitor is recommended for C SENSE. Smaller values will require that larger sense resistors be used. Using a 0.1 µF capacitor results in reasonable values for R SENSE. Figure 5-3 illustrates a typical SENSE network. FIGURE 5-3: Typical Sense Network. The required value of RSENSE will change with the cur- rent rating of the fan and the fan current waveshape. A key point is that the current rating of the fan specified by the manufacturer may be a worst-case rating, with the actual current drawn by the fan being lower than this rating. For the purposes of setting the value for R SENSE, the operating fan current should be measured to get the nominal value. This can be done by using an oscilloscope current probe or using a voltage probe with a low-value resistor (0.5 Ω). Another good tool for this exercise is the TC642 Evaluation Board. This board allows the R SENSE and CSENSE values to be eas- ily changed while allowing the voltage waveforms to be monitored to ensure the proper levels are being reached. Table 5-1 shows values of R SENSE according to the nominal operating current of the fan. The fan currents are average values. If the fan current falls between two of the values listed, use the higher resistor value. - Thermometrics ® - Quality Thermistor ™ - Ametherm ® - Sensor Scientific ™ - U.S. Sensor ™ - Vishay ® - Advanced Thermal Products™ - muRata ® 100 120 140 20 30 40 50 60 70 80 90 100 Temperature (ºC) Network Resistance (k:) 0.000 0.500 1.000 1.500 2.000 2.500 3.000 3.500 4.000 VIN (V) NTC Thermistor 100 k: @ 25ºC VIN Voltage RTEMP FAN RISO RSENSE CSENSE SENSE VOUT (0.1 µF typical) 715Ω Note: See Table 5-1 for RSENSE values.

 2003 Microchip Technology Inc. DS21755B-page 21 TC646B/TC648B/TC649B FIGURE 5-5: Fan Current During a Locked Rotor Condition.

5.5 Output Drive Device Selection

The TC646B/TC648B/TC649B is designed to drive an external NPN transistor or N-channel MOSFET as the fan speed modulating element. These two arrange- ments are shown in Figure 5-7. For lower-current fans, NPN transistors are a very economical choice for the fan drive device. It is recommended that, for higher cur- rent fans (300 mA and above), MOSFETs be used as the fan drive device. Table 5-2 provides some possible part numbers for use as the fan drive element. When using a NPN transistor as the fan drive element, a base current-limiting resistor must be used. This is shown in Figure 5-7. When using MOSFETs as the fan drive element, it is very easy to turn the MOSFETs on and off at very high rates. Because the gate capacitances of these small MOSFETs are very low, the TC646B/TC648B/TC649B can charge and discharge them very quickly, leading to very fast edges. Of key concern is the turn-off edge of the MOSFET. Since the fan motor winding is essentially an inductor, once the MOSFET is turned off the current that was flowing through the motor wants to continue to flow. If the fan does not have internal clamp diodes around the windings of the motor, there is no path for this current to flow through and the voltage at the drain of the MOSFET may rise until the drain-to-source rating of the MOSFET is exceeded. This will most likely cause the MOSFET to go into avalanche mode. Since there is very little energy in this occurrence, it will probably not fail the device, but it would be a long-term reliability issue. The following is recommended:

• Ask how the fan is designed. If the fan has clamp diodes internally, this problem will not be seen. If the fan does not have internal clamp diodes, it is a good idea to install one externally (Figure 5-6). Putting a resistor between V OUT and the gate of the MOSFET will also help slow down the turn-off and limit this condition. FIGURE 5-6: Clamp Diode For Fan Turn- Off. GND RSENSE VOUT Q1: N-Channel MOSFET FAN

DS21755B-page 22  2003 Microchip Technology Inc. FIGURE 5-7: Output Drive Device Configurations. TABLE 5-2: FAN DRIVE DEVICE SELECTION TABLE (NOTE 2)

5.6 Bias Supply Bypassing and Noise

The bias supply (V DD) for the TC646B/TC648B/ TC649B devices should be bypassed with a 1.0 µF ceramic capacitor. This capacitor will help supply the peak currents that are required to drive the base/gate of the external fan drive devices. As the V IN pin controls the duty cycle in a linear fashion, any noise on this pin can cause duty cycle jittering. For this reason, the V IN pin should be bypassed with a 0.01 µF capacitor. In order to keep fan noise off of the TC646B/TC648B/ TC649B device ground, individual ground returns for the TC646B/TC648B/TC649B and the low side of the fan current sense resistor should be used.

5.7 Design Example/Typical

The system has been designed with the following components and criteria: System inlet air ambient temperature ranges from 0ºC to 50ºC. At 20ºC, system cooling is no longer required, so the fan is to be turned off. Prior to turn-off, the fan should be run at 40% of its full fan speed. Full fan speed should be reached when the ambient air is 40ºC. The system has a surface mount, NTC-style thermistor in a 1206 package. The thermistor is mounted on a daughtercard that is directly in the inlet air stream. The thermistor is a NTC, 100 k Ω @ 25ºC, Thermometrics part number NHQ104B425R5. The given Beta for the thermistor is 4250. The system bias voltage to run the fan controller is 5V, while the fan voltage is 12V. Device Package Max Vbe sat / Vgs(V) Min hfe VCE/VDS (V) Fan Current (mA) Suggested Rbase (Ω) MMBT2222A SOT-23 1.2 50 40 150 800 MPS2222A TO-92 1.2 50 40 150 800 MPS6602 TO-92 1.2 50 40 500 301 SI2302 SOT-23 2.5 NA 20 500 Note 1 MGSF1N02E SOT-23 2.5 NA 20 500 Note 1 SI4410 SO-8 4.5 NA 30 1000 Note 1 SI2308 SOT-23 4.5 NA 60 500 Note 1 Note 1: A series gate resistor may be used in order to control the MOSFET turn-on and turn-off times. 2: These drive devices are suggestions only. Fan currents listed are for individual fans. GND Fan Bias RSENSE RBASE VOUT FAN a) Single Bipolar Transistor GND Fan Bias RSENSE VOUT b) N-Channel MOSFET FAN

DS21755B-page 24  2003 Microchip Technology Inc. Step 2: Selecting the Fan Controller. The requirements for the fan controller are that it have auto-shutdown capability at 20ºC and also indicate a fan fault condition. No over-temperature indication is necessary. From these specifications, the proper selection is the TC649B device. Step 3: Setting the PWM Frequency. The fan is rated at 4200 RPM with a 12V input. The goal is to run to a 40% duty cycle (roughly 40% fan speed), which equates to approximately 1700 RPM. At

1700 RPM, one full fan revolution occurs every

35 msec. The fan being used is a four-pole fan that gives four current pulses per revolution. With this infor- mation, and viewing test results at 40% duty cycle, two fan current pulses were always seen during the PWM on time with a PWM frequency of 30 Hz. For this rea- son, the C F value is selected to be 1.0 µF. Step 4: Setting the VIN Voltage. From the design criteria, the desired duty cycle at 20ºC is 40% and full fan speed should be reached at 40ºC. Based on a V IN voltage range of 1.20V to 2.60V, which represents 0% to 100% duty cycle, the 40% duty cycle voltage can be found using the following equation: EQUATION Using the above equation, the V IN values are calculated to be: Using these values along with the thermistor resistance values calculated earlier, the R1 and R2 resistor values can now be calculated using the following equation: EQUATION RTEMP is the parallel combination of R 1 and the ther- mistor. V(T1) represents the V IN voltage at 20ºC and V(T2) represents the V IN voltage at 40ºC. Solving the equations simultaneously yields the following values DD = 5V): -R 1 = 238,455 Ω -R 2 = 45,161 Ω Using standard 1% resistor values, the selected R1 and R2 values are: -R 1 = 237 kΩ -R 2 = 45.3 kΩ A graph of the V IN voltage, thermistor resistance and RTEMP resistance versus temperature for this configuration is shown in Figure 5-10. FIGURE 5-10: Thermistor Resistance, V IN and RTEMP vs. Temperature Step 5: Setting the Auto-Shutdown Voltage (VAS). Setting the voltage for the auto-shutdown is done using a simple resistor voltage divider. The criteria for the voltage divider in this design is that it draw no more than 100 µA of current. The required auto-shutdown voltage was determined earlier in the selection of the V IN voltage at 40% duty cycle, since this was also set at the temperature that auto-shutdown is to occur (20ºC). AS = 1.76V Given this desired setpoint and knowing the desired divider current, the following equations can be used to solve for the resistor values for R 3 and R4: EQUATION Using the equations above, the resistor values for R 3 and R4 are found to be: -R 3 = 32.4 kΩ -R 4 = 17.6 kΩ Using standard 1% resistor values yields the following values: -R 3 = 32.4 kΩ -R 4 = 17.8 kΩ VIN = (DC * 1.4V) + 1.20V DC = Desired Duty Cycle VT 1() VDD R2× VT 2() VDD R2× 100 150 200 250 300 350 400 0 1 02 03 04 05 06 07 08 09 0 Temperature (ºC) Network Resistance (k:) 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 VIN (V) VIN NTC Thermistor 100 k: @ 25ºC RTEMP IDIV = 5V R3 + R4 VAS = 5V * R4 R3 + R4

DS21755B-page 26  2003 Microchip Technology Inc. FIGURE 5-13: Design Example Schematic. Bypass capacitor C VDD is added to the design to decouple the bias voltage. This is good to have, espe- cially when using a MOSFET as the drive device. This helps to give a localized low-impedance source for the current required to charge the gate capacitance of Q Two other bypass capacitors (labeled as CB) were also added to decouple the VIN and VAS nodes. These were added simply to remove any noise present that might cause false triggerings or PWM jitter. R 5 is the pull-up resistor for the FAULT output. The value for this resistor is system-dependent. FAULT SENSE 32.4 kΩ GND +12V +5V VDDVIN VAS VOUT RSENSE CSENSE CF 1.0 µF CF TC649B Fan CB 0.01 µF CB 0.01 µF +5V 17.8 kΩ 237 kΩ 45.3kΩ 10 kΩ 0.1 µF SI2302 or MGSF1N02E Panasonic® 12V, 140 mA FBA06T12H Thermometrics® 100 kΩ@25°C NHQ104B425R5 1.0 µF 3.0Ω CVDD

 2003 Microchip Technology Inc. DS21755B-page 27 TC646B/TC648B/TC649B

6.0 PACKAGING INFORMATION

6.1 Package Marking Information

8-Lead PDIP (300 mil) Example: 8-Lead SOIC (150 mil) Example: XXXXXX XXXYYWW NNN TC646BCPA 025 0215 TC646B COA0215 025 8-Lead MSOP Example: XXXXXX YWWNNN TC646B 215025 Legend: XX...X Customer specific information* Y Year code (last digit of calendar year) YY Year code (last 2 digits of calendar year) WW Week code (week of January 1 is week ‘01’) NNN Alphanumeric traceability code Note: In the event the full Microchip part number cannot be marked on one line, it will be carried over to the next line thus limiting the number of available characters for customer specific information. * Standard device marking consists of Microchip part number, year code, week code, and traceability code.

DS21755B-page 28  2003 Microchip Technology Inc. 8-Lead Plastic Dual In-line (PA) – 300 mil (PDIP) B A L p α E eB β c n D Units INCHES* MILLIMETERS Dimension Limits MIN NOM MAX MIN NOM MAX Number of Pins n 88 Pitch p .100 2.54 Base to Seating Plane A1 .015 0.38 Mold Draft Angle Top α 51 01 5 51 01 5 Mold Draft Angle Bottom β 51 01 5 51 01 5 * Controlling Parameter Notes: Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed JEDEC Equivalent: MS-001 Drawing No. C04-018 .010” (0.254mm) per side. § Significant Characteristic

 2003 Microchip Technology Inc. DS21755B-page 29 TC646B/TC648B/TC649B 8-Lead Plastic Small Outline (OA) – Narrow, 150 mil (SOIC) Foot Angle f 048048 1512015120βMold Draft Angle Bottom 1512015120αMold Draft Angle Top 1.27.050pPitch 88nNumber of Pins MAXNOMMINMAXNOMMINDimension Limits MILLIMETERSINCHES*Units D n p B E h Lβ c 45× f α A * Controlling Parameter Notes: Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed .010” (0.254mm) per side. JEDEC Equivalent: MS-012 Drawing No. C04-057 § Significant Characteristic

DS21755B-page 30  2003 Microchip Technology Inc. 8-Lead Plastic Micro Small Outline Package (UA) (MSOP) D A L c (F) α E p B n 1 φ β Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not .037 REFFFootprint (Reference) exceed .010" (0.254mm) per side. Notes: Drawing No. C04-111 *Controlling Parameter Mold Draft Angle Top Mold Draft Angle Bottom Foot Angle Lead Width Lead Thickness β α c B φ .003 .009 .006 .012 Dimension Limits Overall Height Molded Package Thickness Molded Package Width Overall Length Foot Length Standoff Overall Width Number of Pins Pitch A L D E .016 .024 .118 BSC .118 BSC .000 .030 .193 TYP. .033 MIN p n Units .026 BSC NOM INCHES

0.95 REF

.009 .016 0.08 0.22 0.23 0.40 MILLIMETERS*

0.65 BSC

0.85

3.00 BSC

0.60

4.90 BSC

.043 .031 .037 .006 0.40 0.00 0.75 MINMAX NOM 1.10 0.80 0.15 0.95 MAX 15°5° - 15°5° - JEDEC Equivalent: MO-187 0° - 8° 5° - 15° 15° - -

 2003 Microchip Technology Inc. DS21755B-page 31 TC646B/TC648B/TC649B

6.2 Taping Form

Component Taping Orientation for 8-Pin MSOP Devices User Direction of Feed Standard Reel Component Orientation for 713 or TR Suffix Device W P Carrier Tape, Number of Components Per Reel and Reel Size: Package Carrier Width (W) Pitch (P) Part Per Full Reel Reel Size 8-Pin MSOP 12 mm 8 mm 2500 13 in. PIN 1 Component T aping Orientation for 8-Pin SOIC Devices User Direction of Feed Standard Reel Component Orientation for 713 or TR Suffix Device W P Carrier Tape, Number of Components Per Reel and Reel Size: Package Carrier Width (W) Pitch (P) Part Per Full Reel Reel Size 8-Pin SOIC 12 mm 8 mm 2500 13 in.

DS21755B-page 32  2003 Microchip Technology Inc. NOTES:

 2003 Microchip Technology Inc. DS21755B-page 33 TC646B/TC648B/TC649B PRODUCT IDENTIFICATION SYSTEM To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office . Sales and Support Device: TC646B: PWM Fan Speed Controller with Fan Restart, Auto-Shutdown, Fan Fault and Over-T emp Detection TC648B: PWM Fan Speed Controller with Auto- Shutdown and Over-Temp Detection TC649B: PWM Fan Speed Controller with Fan Restart, Auto-Shutdown and Fan Fault Detection T emperature Range: E = -40°C to +85°C Package: OA = Plastic SOIC, (150 mil Body), 8-lead PA = Plastic DIP (300 mil Body), 8-lead UA = Plastic Micro Small Outline (MSOP), 8-lead 713 = Tape and Reel (SOIC and MSOP) (TC646B and TC648B only) TR = T ape and Reel (SOIC and MSOP) (TC649B only) PART NO. X /XX PackageTemperature Range Device Examples: a) TC646BEOA: SOIC package. b) TC646BEOA713: Tape and Reel, SOIC package. c) TC646BEPA: PDIP package. d) TC646BEUA: MSOP package. a) TC648BEOA: SOIC package. b) TC648BEPA: PDIP package. c) TC648BEUA: MSOP package. d) TC648BEUA713: Tape and Reel, MSOP package. a) TC649BEOA: SOIC package. b) TC649BEOATR: Tape and Reel, SOIC package. c) TC649BEPA: PDIP package. d) TC649BEUA: MSOP package Data Sheets Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and recommended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following: 1. Your local Microchip sales office 2. The Microchip Corporate Literature Center U.S. FAX: (480) 792-7277 3. The Microchip Worldwide Site (www.microchip.com) Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using. Customer Notification System Register on our web site (www.microchip.com/cn) to receive the most current information on our products.

DS21755B-page 34  2003 Microchip Technology Inc. NOTES:

DS21755B-page 35  2003 Microchip Technology Inc. Information contained in this publication regarding device applications and the like is intended through suggestion only and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. No representation or warranty is given and no liability is assumed by Microchip Technology Incorporated with respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights arising from such use or otherwise. Use of Microchip’s products as critical components in life support systems is not authorized except with express written approval by Microchip. No licenses are conveyed, implicitly or otherwise, under any intellectual property rights. Trademarks The Microchip name and logo, the Microchip logo, K EELOQ, MPLAB, PIC, PICmicro, PICSTART, PRO MATE and PowerSmart are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. FilterLab, microID, MXDEV, MXLAB, PICMASTER, SEEVAL and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A. Accuron, Application Maestro, dsPIC, dsPICDEM, dsPICDEM.net, ECONOMONITOR, FanSense, FlexROM, fuzzyLAB, In-Circuit Serial Programming, ICSP, ICEPIC, microPort, Migratable Memory, MPASM, MPLIB, MPLINK, MPSIM, PICC, PICkit, PICDEM, PICDEM.net, PowerCal, PowerInfo, PowerMate, PowerTool, rfLAB, rfPIC, Select Mode, SmartSensor, SmartShunt, SmartT el and Total Endurance are trademarks of Microchip T echnology Incorporated in the U.S.A. and other countries. Serialized Quick Turn Programming (SQTP) is a service mark of Microchip Technology Incorporated in the U.S.A. All other trademarks mentioned herein are property of their respective companies. © 2003, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper. Note the following details of the code protection feature on Microchip devices:

• Microchip products meet the specification contained in their particular Microchip Data Sheet.
• Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used i n the intended manner and under normal conditions.
• There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip's Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
• Microchip is willing to work with the customer who is concerned about the integrity of their code.
• Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as “unbreakable.” Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act. Microchip received QS-9000 quality system certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona in July 1999 and Mountain View, California in March 2002. The Company’s quality system processes and procedures are QS-9000 compliant for its PICmicro ® 8-bit MCUs, KEELOQ® code hopping devices, Serial EEPROMs, microperipherals, non-volatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001 certified.

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San Jose, CA 95131 Tel: 408-436-7950 Fax: 408-436-7955 Toronto

6285 Northam Drive, Suite 108

Mississauga, Ontario L4V 1X5, Canada Tel: 905-673-0699 Fax: 905-673-6509 ASIA/PACIFIC Australia Microchip Technology Australia Pty Ltd Marketing Support Division Suite 22, 41 Rawson Street Epping 2121, NSW Australia Tel: 61-2-9868-6733 Fax: 61-2-9868-6755 China - Beijing Microchip Technology Consulting (Shanghai) Co., Ltd., Beijing Liaison Office Unit 915 Bei Hai Wan Tai Bldg. No. 6 Chaoyangmen Beidajie Beijing, 100027, No. China Tel: 86-10-85282100 Fax: 86-10-85282104 China - Chengdu Microchip Technology Consulting (Shanghai) Co., Ltd., Chengdu Liaison Office Rm. 2401-2402, 24th Floor, Ming Xing Financial Tower No. 88 TIDU Street Chengdu 610016, China Tel: 86-28-86766200 Fax: 86-28-86766599 China - Fuzhou Microchip Technology Consulting (Shanghai) Co., Ltd., Fuzhou Liaison Office Unit 28F, World Trade Plaza No. 71 Wusi Road Fuzhou 350001, China Tel: 86-591-7503506 Fax: 86-591-7503521 China - Hong Kong SAR Microchip Technology Hongkong Ltd. Unit 901-6, Tower 2, Metroplaza

223 Hing Fong Road

Kwai Fong, N.T., Hong Kong Tel: 852-2401-1200 Fax: 852-2401-3431 China - Shanghai Microchip Technology Consulting (Shanghai) Co., Ltd. Room 701, Bldg. B Far East International Plaza No. 317 Xian Xia Road Shanghai, 200051 Tel: 86-21-6275-5700 Fax: 86-21-6275-5060 China - Shenzhen Microchip Technology Consulting (Shanghai) Co., Ltd., Shenzhen Liaison Office Rm. 1812, 18/F, Building A, United Plaza No. 5022 Binhe Road, Futian District Shenzhen 518033, China Tel: 86-755-82901380 Fax: 86-755-82966626 China - Qingdao Rm. B505A, Fullhope Plaza, No. 12 Hong Kong Central Rd. Qingdao 266071, China Tel: 86-532-5027355 Fax: 86-532-5027205 India Microchip Technology Inc. India Liaison Office Marketing Support Division Divyasree Chambers

1 Floor, Wing A (A3/A4)

No. 11, O’Shaugnessey Road Bangalore, 560 025, India Tel: 91-80-2290061 Fax: 91-80-2290062 Japan Microchip Technology Japan K.K. Benex S-1 6F 3-18-20, Shinyokohama Kohoku-Ku, Yokohama-shi Kanagawa, 222-0033, Japan Tel: 81-45-471- 6166 Fax: 81-45-471-6122 Korea Microchip Technology Korea 168-1, Youngbo Bldg. 3 Floor Samsung-Dong, Kangnam-Ku Seoul, Korea 135-882 Tel: 82-2-554-7200 Fax: 82-2-558-5934 Singapore Microchip Technology Singapore Pte Ltd.

200 Middle Road

#07-02 Prime Centre Singapore, 188980 Tel: 65-6334-8870 Fax: 65-6334-8850 Taiwan Microchip Technology (Barbados) Inc., Taiwan Branch 11F-3, No. 207 Tung Hua North Road Taipei, 105, Taiwan Tel: 886-2-2717-7175 Fax: 886-2-2545-0139 EUROPE Austria Microchip Technology Austria GmbH Durisolstrasse 2 A-4600 Wels Austria Tel: 43-7242-2244-399 Fax: 43-7242-2244-393 Denmark Microchip Technology Nordic ApS Regus Business Centre Lautrup hoj 1-3 Ballerup DK-2750 Denmark Tel: 45-4420-9895 Fax: 45-4420-9910 France Microchip Technology SARL Parc d’Activite du Moulin de Massy

43 Rue du Saule Trapu

91300 Massy, France

D-85737 Ismaning, Germany Tel: 49-89-627-144-0 Fax: 49-89-627-144-44 Italy Microchip Technology SRL Via Quasimodo, 12

20025 Legnano (MI)

Milan, Italy Tel: 39-0331-742611 Fax: 39-0331-466781 United Kingdom Microchip Ltd.

505 Eskdale Road

Berkshire, England RG41 5TU Tel: 44-118-921-5869 Fax: 44-118-921-5820 03/25/03 WORLDWIDE SALES AND SERVICE