ADM1030

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REV.0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. a ADM1030* Tel: 781/329-4700 www.analog.com Fax: 781/326-8703 © Analog Devices, Inc., 2001 Intelligent Temperature Monitor and PWM Fan Controller FUNCTIONAL BLOCK DIAGRAM SERIAL BUS INTERFACE INTERRUPT ST A TUS REGISTER VALUE AND LIMIT REGISTERS OFFSET REGISTERS CONFIGURA TION REGISTER LIMIT COMP ARA TOR 2.5V BANDGAP REFERENCE ANALOG MUL TIPLEXERBANDGAP TEMPERA TURE SENSOR SLAVE ADDRESS REGISTER ADD SDA SCL GND ADM1030 FAN CHARACTERISTICS REGISTER FAN SPEED CONFIG REGISTER TMIN/T RANGE REGISTER FAN SPEED COUNTER ADDRESS POINTER REGISTER PWM CONTROLLER T ACH SIGNAL CONDITIONING NC INT THERM FAN_FAULT NC NC NC PWM_OUT T ACH/AIN VCC ADC NC = NO CONNECT

FEATURES

Optimized for Pentium® III: Allows Reduced Guardbanding Software and Automatic Fan Speed Control Automatic Fan Speed Control Allows Control Indepen- dent of CPU Intervention after Initial Setup Control Loop Minimizes Acoustic Noise and Battery Consumption Remote Temperature Measurement Accurate to 1 /H11543C Using Remote Diode 0.125/H11543C Resolution on Remote Temperature Channel Local Temperature Sensor with 0.25 /H11543C Resolution Pulsewidth Modulation Fan Control (PWM) Programmable PWM Frequency Programmable PWM Duty Cycle Tach Fan Speed Measurement Analog Input To Measure Fan Speed of 2-Wire Fans (Using Sense Resistor) 2-Wire System Management Bus (SMBus) with ARA Support Overtemperature THERM Output Pin Programmable INT Output Pin Configurable Offset for All Temperature Channels 3 V to 5.5 V Supply Range Shutdown Mode to Minimize Power Consumption

APPLICATIONS

Notebook PCs, Network Servers and Personal Computers Telecommunications Equipment PRODUCT DESCRIPTION The ADM1030 is an ACPI-compliant two-channel digital ther- mometer and under/over temperature alarm, for use in computers and thermal management systems. Optimized for the Pentium III, the higher 1°C accuracy offered allows sys tems designers to safely reduce temperature guardbanding and increase system performance. A Pulsewidth Modulated (PWM) Fan Control out- put controls the speed of a cooling fan by varying output duty cycle. Duty cycle values between 33%–100% allow smooth control of the fan. The speed of the fan can be monitored via a TACH input for a fan with a tach output. The TACH input can be programmed as an analog input, allowing the speed of a 2-wire fan to be determined via a sense resistor. The device will also detect a stalled fan. A dedicated Fan Speed Control Loop pro- vides control even without the intervention of CPU software. It also ensures that if the CPU or system locks up, the fan can s till be controlled based on temperature measurements, and the fan speed adjusted to correct any changes in system tem perature. Fan Speed may also be controlled using existing ACPI software. One input (two pins) is dedicated to a remote t emperature- sensing diode with an accuracy of ±1°C, and a local temperature sensor allows ambient temperature to be monitored. The device has a programmable INT output to indicate error conditions. There is a dedicated FAN_FAULT output to signal fan failure. The THERM pin is a fail-safe output for over -temperature conditions that can be used to throttle a CPU clock. *Patents pending. Pentium is a registered trademark of Intel Corporation.

REV. 0–2– ADM1030–SPECIFICATIONS1 (TA = TMIN to TMAX, VCC = VMIN to VMAX, unless otherwise noted.) Parameter Min Typ Max Unit Test Conditions/Comments POWER SUPPLY Supply Voltage, V CC 3.0 3.30 5.5 V Supply Current, I CC 1.4 3 mA Interface Inactive, ADC Active 32 50 µA Standby Mode TEMPERATURE-TO-DIGITAL CONVERTER Internal Sensor Accuracy ±1 ±3 °C Resolution 0.25 °C External Diode Sensor Accuracy ±1 °C6 0 °C ≤ TD ≤ 100°C Resolution 0.125 °C Remote Sensor Source Current 180 µA High Level 11 µA Low Level OPEN-DRAIN DIGITAL OUTPUTS (THERM, INT, FAN_FAULT, PWM_OUT) Output Low Voltage, V OL 0.4 V I OUT = –6.0 mA; VCC = 3 V High-Level Output Leakage Current, I OH 0.1 1 µAV OUT = VCC; VCC = 3 V DIGITAL INPUT LEAKAGE CURRENT Input High Current, I IH –1 µAV IN = VCC Input Low Current, I IL 1 µAV IN = 0 Input Capacitance, C IN 5p F DIGITAL INPUT LOGIC LEVELS 2 (ADD, THERM, TACH) Input High Voltage, V IH 2.1 V Input Low Voltage, V IL 0.8 V OPEN-DRAIN SERIAL DATA BUS OUTPUT (SDA) Output Low Voltage, V OL 0.4 V I OUT = –6.0 mA; VCC = 3 V High-Level Output Leakage Current, I OH 0.1 1 µAV OUT = VCC SERIAL BUS DIGITAL INPUTS (SCL, SDA) Input High Voltage, V IH 2.1 V Input Low Voltage, V IL 0.8 V Hysteresis 500 mV FAN RPM-TO-DIGITAL CONVERTER Accuracy ±6% 6 0 °C ≤ TA ≤ 100°C Resolution 8 Bits TACH Nominal Input RPM 4400 RPM Divisor N = 1, Fan Count = 153

2200 RPM Divisor N = 2, Fan Count = 153

1100 RPM Divisor N = 4, Fan Count = 153

550 RPM Divisor N = 8, Fan Count = 153

Conversion Cycle Time 637 ms SERIAL BUS TIMING 3 Clock Frequency, f SCLK 10 100 kHz See Figure 1 Glitch Immunity, t SW 50 ns See Figure 1 Bus Free Time, t BUF 4.7 µs See Figure 1 Start Setup Time, t SU;STA 4.7 µs See Figure 1 Start Hold Time, t HD;STA 4 µs See Figure 1 Stop Condition Setup Time t SU;STO 4 µs See Figure 1 SCL Low Time, t LOW 1.3 µs See Figure 1 SCL High Time, t HIGH 45 0 µs See Figure 1 SCL, SDA Rise Time, t R 1000 ns See Figure 1 SCL, SDA Fall Time, t F 300 ns See Figure 1 Data Setup Time, t SU;DAT 250 ns See Figure 1 Data Hold Time, t HD;DAT 300 ns See Figure 1 NOTES 1Typicals are at T A = 25°C and represent most likely parametric norm. Shutdown current typ is measured with V CC = 3.3 V. 2ADD is a three-state input that may be pulled high, low or left open-circuit. 3Timing specifications are tested at logic levels of V IL = 0.8 V for a falling edge and V IH = 2.2 V for a rising edge. Specifications subject to change without notice.

conditions for extended periods may affect device reliability. Figure 1. Diagram for Serial Bus Timing

REV. 0 ADM1030 –4– PIN FUNCTION DESCRIPTIONS Pin No. Mnemonic Description 1 PWM_OUT Digital Output (Open-Drain). Pulsewidth modulated output to control fan speed. Requires pull- up resistor (10 kΩ typical). 2 TACH/AIN Digital/Analog Input. Fan tachometer input to measure fan speed. May be reprogrammed as an analog input to measure speed of a 2-wire fan via a sense resistor (2 Ω typical) 3, 4, 11, 12 NC Not Connected. 5 GND System Ground. 6V CC Power. Can be powered by 3.3 V Standby power if monitoring in low power states is required. 7 THERM Digital I/O (Open-Drain). An active low thermal overload output that indicates a violation of a temperature set point (overtemperature). Also acts as an input to provide external fan control. When this pin is pulled low by an external signal, a status bit is set, and the fan speed is set to full-on. Requires pull-up resistor (10 k Ω). 8 FAN_FAULT Digital Output (Open-Drain). Can be used to signal a fan failure. Requires pull-up resistor (typically 10 kΩ). 9 D– Analog Input. Connected to cathode of an external temperature-sensing diode. The temperature- sensing element is either a Pentium III substrate transistor or a general-purpose 2N3904. 10 D+ Analog Input. Connected to anode of the external temperature-sensing diode. 13 ADD Three-state Logic Input. Sets two lower bits of device SMBus address. 14 INT Digital Output (Open-Drain). Can be programmed as an interrupt output for temperature/fan speed interrupts. Requires pull-up resistor (10 k Ω typical). 15 SDA Digital I/O. Serial Bus Bidirectional Data. Open-drain output. Requires pull-up resistor (2.2 k Ω typical). 16 SCL Digital Input. Serial Bus Clock. Requires pull-up resistor (2.2 k Ω typ). PIN CONFIGURATION TOP VIEW (Not to Scale) PWM_OUT SCL ADM1030 T ACH/AIN SDA NC INT NC ADD GND NC VCC NC THERM D+ FAN_FAULT D– NC = NO CONNECT

REV. 0 –5– Typical Performance Characteristics–ADM1030 LEAKAGE RESIST ANCE – M/H9024 1 1003.3 REMOTE TEMPERA TURE ERROR – /H11543C 10 30 –20 –10 –15 DXP TO GND DXP TO VCC (3.3V) TPC 1. Temperature Error vs. PCB Track Resistance FREQUENCY – Hz REMOTE TEMPERA TURE ERROR – /H11543C15 500k 2M 4M 6M 10M 100M 400M VIN = 100mV p-p VIN = 200mV p-p TPC 2. Temperature Error vs. Power Supply Noise Frequency FREQUENCY – Hz 0 400M100k 1M 100M 200M 300M 500M REMOTE TEMPERA TURE ERROR – /H11543C VIN = 40mV p-p VIN = 20mV p-p TPC 3. Temperature Error vs. Common-Mode Noise Frequency PIII TEMPERA TURE – /H11543C 06 0 10 READING – /H11543C 20 30 40 50 70 80 90 100 110 110 100 TPC 4. Pentium III Temperature Measurement vs. ADM1030 Reading DXP – DXN CAP ACIT ANCE – nF –10 14 7 2.2 REMOTE TEMPERA TURE ERROR – /H11543C 3.3 4.7 10 22 –11 –12 –13 –14 –15 –16 TPC 5. Temperature Error vs. Capacitance between D+ and D– SCLK FREQUENCY – kHz 0 751 SUPPL Y CURRENT – /H9262A 5 10 25 50 100 250 500 750 1000 100 110 VCC = 5V VCC = 3.3V TPC 6. Standby Current vs. Clock Frequency

REV. 0 ADM1030 –6– TPC 7. Temperature Error vs. Differential-Mode Noise Frequency TPC 8. Standby Supply Current vs. Supply Voltage TPC 9. Local Sensor Error TPC 10. Remote Sensor Error TPC 11. Supply Current vs. Supply Voltage FREQUENCY – Hz 0 400M100k REMOTE TEMPERA TURE ERROR – /H11543C 1M 100M 200M 300M 500M VIN = 30mV p-p VIN = 20mV p-p SUPPL Y VOL T AGE – V 200SUPPL Y CURRENT – /H9262A 180 160 140 120 100 –20 ADD = Hi-Z ADD = GND ADD = VCC TEMPERA TURE – /H11543C 0.08 ERROR – /H11543C –0.08 –0.16 –0.24 –0.32 –0.40 –0.48 –0.56 –0.64 –0.72 –0.80 20 40 60 80 85 100 105 120 SUPPL Y VOL T AGE – V 1.30 0.80 2.0 SUPPL Y CURRENT – mA 2.4 1.25 1.20 1.15 1.05 0.95 1.10 1.00 0.90 0.85 TIME – Sec 120 TEMPERA TURE – /H11543C 110 100 468 1 013579 TPC 12. Response to Thermal Shock TEMPERA TURE – /H11543C 0.16 ERROR – /H11543C 0.08 –0.08 –0.16 –0.24 –0.32 –0.40 –0.48 –0.56 –0.64 –0.72 –0.80 –0.88 20 40 60 80 85 100 105 120

REV. 0 ADM1030 –7– GENERAL DESCRIPTION The ADM1030 is a temperature monitor and PWM fan control- ler for microprocessor-based systems. The device communicates with the system via a serial System Management Bus. The serial bus controller has a hardwired address pin for device selection (Pin 13), a serial data line for reading and writing addresses and data (Pin 15), and an input line for the serial clock (Pin 16). All control and programming functions of the ADM1030 are per- formed over the serial bus. The device also supports the SMBus Alert Response Address (ARA) function. INTERNAL REGISTERS OF THE ADM1030 A brief description of the ADM1030’s principal internal regis- ters is given below. More detailed information on the function of each register is given in Table XII to Table XXVI. Configuration Register Provides control and configuration of various functions on the device. Address Pointer Register This register contains the address that selects one of the other internal registers. When writing to the ADM1030, the first byte of data is always a register address, which is written to the Address Pointer Register. Status Registers These registers provide status of each limit comparison. Value and Limit Registers The results of temperature and fan speed measurements are stored in these registers, along with their limit values. Fan Speed Config Register This register is used to program the PWM duty cycle for the fan. Offset Registers Allows the temperature channel readings to be offset by a 5-bit two’s complement value written to these registers. These values will automatically be added to the temperature values (or sub- tracted from if negative). This allows the systems designer to optimize the system if required, by adding or subtracting up to 15°C from a temperature reading. Fan Characteristics Register This register is used to select the spin-up time, PWM frequency, and speed range for the fan used. THERM Limit Registers These registers contain the temperature values at which THERM will be asserted. TMIN/TRANGE Registers These registers are read/write registers that hold the minimum temperature value below which the fan will not run when the device is in Automatic Fan Speed Control Mode. These regis- ters also hold the values defining the range over that auto fan control will be provided, and hence determines the temperature at which the fan will run at full speed. SERIAL BUS INTERFACE Control of the ADM1030 is carried out via the SMBus. The ADM1030 is connected to this bus as a slave device, under the control of a master device, e.g., the 810 chipset. The ADM1030 has a 7-bit serial bus address. When the device is powered up, it will do so with a default serial bus address. The five MSBs of the address are set to 01011, the two LSBs are determined by the logical state of Pin 13 (ADD). This is a three-state input that can be grounded, connected to V CC, or left open-circuit to give three different addresses. The state of the ADD pin is only sampled at power-up, so changing ADD with power on will have no effect until the device is powered off, then on again. Table I. ADD Pin Truth Table ADD Pin A1 A0 GND 0 0 No Connect 1 0 VCC 01 If ADD is left open-circuit, the default address will be 0101110. The facility to make hardwired changes at the ADD pin allows the user to avoid conflicts with other devices sharing the same serial bus, for example, if more than one ADM1030 is used in a system. The serial bus protocol operates as follows: 1. The master initiates data transfer by establishing a START condition, defined as a high-to-low transition on the serial data line SDA while the serial clock line SCL remains high. This indicates that an address/data stream will follow. All slave peripherals connected to the serial bus respond to the START condition, and shift in the next 8 bits, consisting of a 7-bit address (MSB first) plus an R/ W bit that determines the direction of the data transfer, i.e., whether data will be written to or read from the slave device. The peripheral whose address corresponds to the transmitted address responds by pulling the data line low during the low period before the ninth clock pulse, known as the Acknowl- edge Bit. All other devices on the bus now remain idle while the selected device waits for data to be read from or written to it. If the R/ W bit is a 0, the master will write to the slave device. If the R/W bit is a 1, the master will read from the slave device. 2. Data is sent over the serial bus in sequen ces of nine clock pulses, eight bits of data followed by an Acknowledge Bit from the slave device. Transitions on the data line must occur during the low period of the clock signal and remain stable during the high period, as a low-to-high transition when the clock is high may be interpreted as a STOP signal. The number of data bytes that can be transmitted over the serial bus in a single READ or WRITE operation is limited only by what the master and slave devices can handle. 3. When all data bytes have been read or written, stop condi- tions are established. In WRITE mode, the master will pull the data line high during the tenth clock pulse to assert a STOP condition. In READ mode, the master device will override the acknowledge bit by pulling the data line high during the low period before the ninth clock pulse. This is known as No Acknowledge. The master will then take the data line low during the low period before the tenth clock pulse, then high during the tenth clock pulse to assert a STOP condition. Any number of bytes of data may be transferred over the serial bus in one operation, but it is not possible to mix read and write in one operation, because the type of operation is determined at the beginning and cannot subsequently be changed without starting a new operation.

Register (Register 0x06), and is outlined in Table XVIII. but is biased above ground by an internal diode at the D– input. temperature measurement nominally takes 9.6 ms.

Place the ADM1030 as close as possible to the remote sens-

distance can be 4 to 8 inches.

Route the D+ and D– tracks close together, in parallel, with

under the tracks if possible.

Use wide tracks to minimize inductance and reduce noise pick-

up. 10 mil track minimum width and spacing is recommended. Figure 4. Arrangement of Signal Tracks

Try to minimize the number of copper/solder joints, which

path and at the same temperature. them, thermocouple voltages should be much less than 200 µV.

Place a 0.1 µF bypass capacitor close to the ADM1030.
If the distance to the remote sensor is more than 8 inches, the
For really long distances (up to 100 feet) use shielded twisted

nected to avoid ground loops. tance should not exceed 1000 pF. introduces about 0.5°C error. attached to the System Management Bus. The ADM1030 has two interrupt outputs, INT and THERM. (described in more detail later).

by setting Bit 7 of Configuration Register 1 (Register 0x00). 00 Remote Temperature Controls the Fan.

11 Maximum Speed Calculated by Local and Remote

Temperature Channels Control the Fan. fore, the fan will be driven at 66% duty cycle. temperature on the other channel. Figure 9. Max Speed Calculated by Local and Remote

Program a value for T MIN.
Program a value for the slope T RANGE.
Program a value for Fan Spin-up Time.
Program the desired Automatic Fan Speed Control Mode

Behavior, i.e., which temperature channel controls the fan.

Select Automatic Fan Speed Control Mode by setting Bit 7

of Configuration Register 1. to 33%, the fan control loops will operate as previously described.

duty cycle affects the control loop behavior. Figure 10. Effect of Changing Minimum Duty Cycle on Register and PWM duty cycle obtained. MAX = Temperature at which fan runs full-speed. TMIN = Temperature at which fan will turn on. Max DC = Maximum Duty Cycle (100%) = 15 decimal. Config Register (default = 33% = 5 decimal). TRANGE = PWM Duty Cycle versus Temperature Slope.

REV. 0 ADM1030 –15– RELEVANT REGISTERS FOR AUTOMATIC FAN SPEED CONTROL MODE Register 0x00 Configuration Register 1 <7> Logic 1 selects Automatic Fan Speed Control, Logic 0 selects software control (Default = 1). <6:5> 00 = Remote Temperature controls Fan 11 = Fastest Calculated Speed controls the fan when Bit 7 = Logic 1. Register 0x20 Fan Characteristics Register 1 <2:0> Fan 1 Spin-Up Time 000 = 200 ms 001 = 400 ms 010 = 600 ms 011 = 800 ms 100 = 1 sec 101 = 2 secs (Default) 110 = 4 secs 111 = 8 secs <5:3> PWM Frequency Driving the Fan 000 = 11.7 Hz 001 = 15.6 Hz 010 = 23.4 Hz 011 = 31.25 Hz (Default) 100 = 37.5 Hz 101 = 46.9 Hz 110 = 62.5 Hz 111 = 93.5 Hz <7:6> Speed Range N; defines the lowest fan speed that can be measured by the device. 00 = 1: Lowest Speed = 2647 RPM 01 = 2: Lowest Speed = 1324 RPM 10 = 4: Lowest Speed = 662 RPM 11 = 8: Lowest Speed = 331 RPM Register 0x22 Fan Speed Configuration Register <3:0> Min Speed: This nibble contains the speed at which the fan will run when the temperature is at TMIN. The default is 0x05, meaning that the fan will run at 33% duty cycle when the temperature is at T MIN. Register 0x24 Local Temp T MIN/TRANGE <7:3> Local Temp TMIN. These bits set the temperature at which the fan will turn on when under Auto Fan Speed Control. TMIN can be programmed in 4 °C increments. 00000 = 0°C 00001 = 4°C 00010 = 8°C 00011 = 12°C 01000 = 32°C (Default) 11110 = 120°C 11111 = 124°C <2:0> Local Temperature T RANGE. This nibble sets the tem- perature range over which Automatic Fan Speed Control takes place. 000 = 5°C 001 = 10°C 010 = 20°C 011 = 40°C 100 = 80°C Register 0x25 Remote Temperature T MIN/TRANGE <7:3> Remote Temperature T MIN. Sets the temperature at which the fan will switch on based on Remote Tempera- ture Readings. 00000 = 0°C 00001 = 4°C 00010 = 8°C 00011 = 12°C 01100 = 48°C 11110 = 120 11111 = 124°C <2:0> Remote Temperature T RANGE. This nibble sets the tem- perature range over which the fan will be controlled based on Remote Temperature readings. 000 = 5°C 001 = 10°C 010 = 20°C 011 = 40°C 100 = 80°C

will effectively be ignored, and the fan’s operation will be smooth. change the number of temperature readings taken per second. setting Bit 7 of Configuration Register 1 (Register 0x00) to 1.

160 TIME

80 TIME

240 TIME SLOTS

Figure 11. 33% PWM Duty Cycle Represented in Time Filtered Mode algorithm operates. Figure 12. Filtered Mode Algorithm very rapidly, the fan gradually ramps up to full speed.

100 RTEMP

Figure 13. Filtered Mode with Ramp Rate = 8 the fan to reach full speed. Figure 14. Filtered Mode with Ramp Rate = 4 Figure 15 shows the PWM output response for a ramp rate of 2. Figure 15. Filtered Mode with Ramp Rate = 2 Figure 16. Filtered Mode with Ramp Rate = 1 rate programmed into the Fan Filter Register. Figure 17. How Fan Reacts to Temperature Variation in

REV. 0 ADM1030 –18– Effect of ADC Sample Rate on Filtered Mode The second means by which to change the Filtered Mode char- acteristics is to adjust the ADC sample rate. The faster the ADC sample rate, the more temperature samples are obtained per second. One way to apply filtering to the control loop is to slow down the ADC sampling rate. This means that the num- ber of iterations of the Filtered Mode algorithm per second are effectively reduced. If the number of temperature measure- ments per second are reduced, how often the PWM_OUT signal controlling the fan is updated is also reduced. Bits <4:2> of the Fan Filter Register (Reg 0x23) set the ADC sample rate. The default ADC sample rate is 1.4 kHz. The ADC sample rate is selectable from 87.5 Hz to 11.2 kHz. Table IX sh ows how many temperature samples are obtained per second, for each of the ADC sample rates. Table IX. Temperature Updates per Second ADC Sample Rate Temperature Updates/Sec 87.5 Hz 0.0625 175 Hz 0.125 350 Hz 0.25 700 Hz 0.5 1.4 kHz 1 (Default) 2.8 kHz 2 5.6 kHz 4 11.2 kHz 8 RELEVANT REGISTERS FOR FILTERED AUTOMATIC FAN SPEED CONTROL MODE In addition to the registers used to program the normal Auto- matic Fan Speed Control Mode, the following register needs to be programmed. Register 0x23 Fan Filter Register <7> Spin-up Disable :- when this bit is set to 1, fan spin-up is disabled. (Default = 0) <6:5> Ramp Rate: these bits set the ramp rate for filtered mode. 00 = 1 (0.416% Duty Cycle Change) 01 = 2 (0.833% Duty Cycle Change) 10 = 4 (1.66% Duty Cycle Change) 11 = 8 (3.33% Duty Cycle Change) <4:2> ADC Sample Rate 000 = 87.5 Hz 001 = 175 Hz 010 = 350 Hz 011 = 700 Hz 100 = 1.4 kHz (Default) 101 = 2.8 kHz 110 = 5.6 kHz 111 = 11.2 kHz <1> Unused. Default = 0 <0> Fan 1 Filter Enable: when this bit is set to 1, it enables filtering on Fan 1. Default = 0. PROGRAMMING THE FILTERED AUTOMATIC FAN SPEED CONTROL LOOP 1. Program a value for T MIN. 2. Program a value for the slope T RANGE. 3. T MAX = TMIN + TRANGE. 4. Program a value for Fan Spin-up Time. 5. Program the desired Automatic Fan Speed Control Mode Behavior, i.e., which temperature channel controls the fan. 6. Program a ramp rate for the filtered mode. 7. Program the ADC sample rate in the Fan Filter Register. 8. Set Bit 0 to enable fan filtered mode for the fan. 9. Select Automatic Fan Speed Control Mode by setting Bit 7 of Configuration Register 1. PWM DUTY CYCLE SELECT MODE The ADM1030 may be operated under software control by clear- ing Bit 7 of Configuration Register 1 (Register 0x00). This allows the user to directly control PWM Duty Cycle. Clearing Bit 5 of Configuration Register 1 allows fan control by varying PWM duty cycle. Values of duty cycle between 0% to 100% may be written to the Fan Speed Config Register (0x22) to control the speed of the fan. Table X shows the relationship between hex values written to the Fan Speed Configuration Register and PWM duty cycle obtained. Table X. PWM Duty Cycle Select Mode Hex Value PWM Duty Cycle 00 0% 01 7% 02 14% 03 20% 04 27% 05 33% 06 40% 07 47% 08 53% 09 60% 0A 67% 0B 73% 0C 80% 0D 87% 0E 93% 0F 100%

REV. 0 ADM1030 –19– RPM FEEDBACK MODE The second method of fan speed control under software is RPM Feedback Mode. This involves programming the desired fan RPM value to the device to set fan speed. The advantages include a very tightly maintained fan RPM over the fan’s life, and virtu- ally no acoustic pollution due to fan speed variation. Fans typically have manufacturing tolerances of ±20%, meaning a wide variation in speed for a typical batch of identical fan models. If it is required that all fans run at exactly 5000 RPM, it may be necessary to specify fans with a nominal fan speed of 6250 RPM. However, many of these fans will run too fast and make excess noise. A fan with nominal speed of 6250 RPM could run as fast as 7000 RPM at 100% PWM duty cycle. RPM Mode will allow all of these fans to be programmed to run at the desired RPM value. Clearing Bit 7 of Configuration Register 1 (Reg 0x00) to 0 places the ADM1030 under software control. Once under soft- ware control, the device may be placed in to RPM Feedback Mode by writing to Bit 5 of Configuration Register 1. Writing a 1 to Bit 5 selects RPM Feedback Mode for the fan. Once RPM Feedback Mode has been selected, the required fan RPM may be written to the Fan Tach High Limit Register (0x10). The RPM Feedback Mode function allows a fan RPM value to be programmed into the device, and the ADM1030 will maintain the selected RPM value by monitoring the fan tach and speed- ing up the fan as necessary, should the fan start to slow down. Conversely, should the fan start to speed up due to aging, the RPM feedback will slow the fan down to maintain the correct RPM speed. The value to be programmed into each Fan Tach High Limit Register is given by: Count = (f × 60)/R × N where: f = 11.25 kHz R = desired RPM value N = Speed Range; MUST be set to 2 The speed range, N, really determines what the slowest fan speed measured can be before generating an interrupt. The slowest fan speed will be measured when the count value reaches 255. Since speed range, N, = 2, Count = (f × 60)/R × N R = (f × 60)/Count × N R = (11250 × 60)/255 × 2 R = (675000)/510 R = 1324 RPM, fan fail detect speed. Programming RPM Values in RPM Feedback Mode Rather than writing a value such as 5000 to a 16-bit register, an 8-bit count value is programmed instead. The count to be pro- grammed is given by: Count = (f × 60)/R × N where: f = 11.25 kHz R = desired RPM value N = Speed Range = 2 Example 1: If the desired value for RPM Feedback Mode is 5000 RPM, what value needs to be programmed for Count? Count = (f × 60)/R × N Since the desired RPM value, R, is 5000 RPM, the value for Count is: N = 2: Count = (11250 × 60)/5000 × 2 Count = 675000/10000 Count = 67 (assumes 2 tach pulses/rev). Example 2: If the desired value for RPM Feedback Mode is 3650 RPM, what value needs to be programmed for Count? Count = (f × 60)/R × N Since the desired RPM value, R, is 3650 RPM, the value for Count is: N = 2: Count = (11250 × 60)/3650 × 2 Count = 675000/7300 Count = 92 (assumes 2 tach pulses/rev). Once the count value has been calculated, it should be written to the Fan Tach High Limit Register. It should be noted that in RPM Feedback Mode, there is no high limit register for under- speed detection that can be programmed as there are in the other fan speed control modes. The only time each fan will indicate a fan failure condition is whenever the count reaches 255. Since the speed range N = 2, the fan will fail if its speed drops below 1324 RPM. Programming RPM Values 1. Choose the RPM value to be programmed. 2. Set speed range value, N = 2. 3. Calculate count value based on RPM and speed range val- ues chosen. Use Count Equation to calculate Count Value. 4. Clear Bit 7 of Configuration Register 1 (Reg. 0x00) to place the ADM1030 under software control. 5. Write a 1 to Bit 5 of Configuration Register 1 to place the device in RPM Feedback Mode. 6. Write the calculated Count value to the Fan Tach High Limit Register (Reg. 0x10). The fan speed will now go to the desired RPM value and maintain that fan speed. RPM Feedback Mode Limitations RPM feedback mode only controls Fan RPM over a limited fan speed range of about 75% to 100%. However, this should be enough range to overcome fan manufacturing tolerance. In prac- tice, however, the program must not function at too low an RPM value for the fan to run at, or the RPM Mode will not operate. To find the lowest RPM value allowed for a given fan, do the following:

REV. 0 ADM1030 –23– Table XII. Registers Address A7–A0 Register Name in Hex Comments Value Registers 0x06–0x1A See Table XIII. Device ID Register 0x3D This location contains the device identification number. Since this device is the ADM1030, this register contains 0x30. This register is read only. Company ID 0x3E This location contains the company identification number (0x41). This register is read only. THERM Behavior/Revision 0x3F This location contains the revision number of the device. The lower four bits reflect device revisions [3:0]. Bit 7 of this register is the THERM-to-fan enable bit. See Table XXIV. Configuration Register 1 0x00 See Table XIV. Power-on value = 1001 0000. Configuration Register 2 0x01 See Table XV. Power-on value = 0111 1111. Status Register 1 0x02 See Table XVI. Power-on value = 0000 0000. Status Register 2 0x03 See Table XVII. Power-on value = 0000 0000. Manufacturer’s Test Register 0x07 This register is used by the manufacturer for test purposes only. This register should not be read from or written to in normal operation. Fan Characteristics Register 1 0x20 See Table XIX. Power-on value = 0101 1101. Fan Speed Configuration Register 0x22 See Table XX. Power-on value = 0101 0101. Fan Filter Register 0x23 See Table XXI. Power-on value = 0101 0101. Local Temperature T MIN/TRANGE 0x24 See Table XXII. Power-on value = 0100 0001. Remote Temperature T MIN/TRANGE 0x25 See Table XXIII. Power-on value = 0110 0001. Table XIII. Value and Limit Registers Address Read/Write Description 0x06 Read/Only Extended Temperature Resolution (see Table XVIII). 0x08 Read/Write Fan Speed Reading—this register contains the fan speed tach measurement. 0x0A Read/Only Local Temperature Value—this register contains the 8 MSBs of the local temperature measurement. 0x0B Read/Only Remote Temperature Value—this register contains the 8 MSBs of the remote temperature reading. 0x0D Read/Write Local Temperature Offset—See Table XXV. 0x0E Read/Write Remote Temperature Offset—See Table XXVI. 0x10 Read/Write Fan Tach High Limit—this register contains the limit for the fan tach measurement. Since the tach circuit counts between pulses, a slow fan will result in a large measured value, so exceeding the limit by one is the way to detect a slow or stalled fan. (Power-On Default = FFh) 0x14 Read/Write Local Temperature High Limit (Power-On Default 60 °C). 0x15 Read/Write Local Temperature Low Limit (Power-On Default 0 °C). 0x16 Read/Write Local Temperature Therm Limit (Power-On Default 70 °C). 0x18 Read/Write Remote Temperature High Limit (Power-On Default 80 °C). 0x19 Read/Write Remote Temperature Low Limit (Power-On Default 0 °C). 0x1A Read/Write Remote Temperature Therm Limit (Power-On Default 100 °C).

REV. 0 ADM1030 –24– Table XIV. Register 0x00 Configuration Register 1 Power-On Default 90h Bit Name R/ W Description 0 MONITOR Read/Write Setting this bit to a “1” enables monitoring of temperature and enables measurement of the fan tach signals. (Power-Up Default = 0.) 1 INT Enable Read/Write Setting this bit to a “1” enables the INT output. 1 = Enabled 0 = Disabled (Power-Up Default = 0). 2 TACH/AIN Read/Write Clearing this bit to “0” selects digital fan speed measurement via the TACH pins. Setting this bit to “1” configures the TACH pins as analog inputs that can measure the speed of 2-wire fans via a sense resistor. (Power-Up Default = 0.) 3 PWM Invert Read/Write Setting this bit to “1” inverts the PWM signal on the output pin. (Power-Up Default = 0). The power-up default makes the PWM_OUT pin go low for 100% duty cycle (suitable for driving the fan using a PMOS device). Setting this bit to “1” makes the PWM_OUT pin high for 100% duty cycle (intended for driving the fan using an NMOS device). 4 Fan Fault Enable Read/Write Logic 1 enables FAN_FAULT pin; Logic 0 disables FAN_FAULT output. (Power-Up Default = 1.) 6–5 PWM Mode Read/Write These two bits control the behavior of the fan in Auto Fan Speed Control Mode. 00 = Remote Temp controls Fan. (Program PWM duty cycle in Software Mode.) 11 = Fastest Calculated Speed Controls Fan. (Program RPM speed in Software Mode.) 7 Auto/SW Ctrl Read/Write Logic 1 selects Automatic Fan Speed Control; Logic 0 selects SW control. (Power-Up Default = 1) When under software control, PWM duty cycle or RPM values may be programmed for the fan. Table XV. Register 0x01 Configuration 2 Power-On Default = 7FH Bit Name R/ W Description 0 PWM 1 En Read/Write Enables fan PWM output when this bit is a “1.” 1 Unused Read/Write Unused. 2 TACH 1 En Read/Write Enables Tach input when set to “1.”

3 Unused

4 Loc Temp En Read/Write Enables Interrupts on Local Channel when set to “1.” 5 Remote Temp En Read/Write Enables Interrupts on Remote Channel when set to “1.” Default is normally enabled, except when a diode fault is detected on power-up. 6 Unused Read/Write Unused. 7 SW Reset Read/Write When set to “1,” resets the device. Self-clears. Power-Up Default = 0.

REV. 0 ADM1030 –25– Table XVI. Register 0x02 Status Register 1 Power-On Default = 00H Bit Name R/ W Description 0 Alarm Speed Read Only This bit is set to “1” when fan is running at alarm speed. Once read, this bit will not reassert on next monitoring cycle, even if the fan is still running at alarm speed. This gives an indication as to when the fan is running full-speed, such as in a THERM condition. 1 Fan Fault Read Only This bit is set to “1” if fan becomes stuck or is running under speed. Once read, this bit will reassert on next monitoring cycle, if the fan failure condi- tion persists. 2 Remote Temp High Read Only “1” indicates Remote high temperature limit has been exceeded. If the tem- perature is still outside the Remote Temp High Limit, this bit will reassert on next monitoring cycle. 3 Remote Temp Low Read Only “1” indicates Remote low temperature limit exceeded (below). If the tempera- ture is still outside the Remote Temp Low Limit, this bit will reassert on next monitoring cycle. 4 Remote Temp Therm Read Only “1” indicates Remote temperature Therm limit has been exceeded. This bit is cleared on a read of Status Register 1. Once cleared, this bit will not get reas- serted even if the THERM condition persists. 5 Remote Diode Error Read Only This bit is set to “1” if a short or open is detected on the remote temperature channel. This test is only done on power-up, and if set to 1 cannot be cleared by reading the Status Register 1. 6 Loc Temp High Read Only “1” indicates Local Temp High Limit has been exceeded. If the temperature is still outside the Local Temp High Limit, this bit will reassert on next monitoring cycle. 7 Loc Temp Low Read Only “1” indicates Local Temp Low Limit has been exceeded (below). If the tem- perature is still outside the Local Temp Low Limit, this bit will reassert on next monitoring cycle. Table XVII. Register 0x03 Status Register 2 Power-Up Default = 00H Bit Name R/ W Description 0 Unused Read Only Unused. 1 Unused Read Only Unused. 2 Unused Read Only Unused. 3 Unused Read Only Unused. 4 Unused Read Only Unused. 5 Unused Read Only Unused. 6 Loc Therm Read Only “1” indicates Local temperature Therm limit has been exceeded. This bit clears on a read of Status Register 2. Once cleared, this bit will not be reasserted even if the THERM con- dition persists. 7 THERM Read Only Set to “1” when THERM is pulled low as an input. This bit clears on a read of Status Register 2. The fan also runs full-speed. Table XVIII. Register 0x06 Extended Temperature Resolution Power-On Default = 00H Bit Name R/ W Description <2:0> Remote Temp Read Only Holds extended temperature resolution bits for Remote Tem perature channel. <5:3> Reserved Read Only Reserved. <7:6> Local Temp Read Only Holds extended temperature resolution bits for Local Temperature channel.

REV. 0 ADM1030 –26– Table XIX. Register 0x20 Fan Characteristics Register 1 Power-On Default = 5DH Bit Name R/ W Description <2:0> Fan 1 Spin-up Read/Write These bits contain the Fan Spin-up time to allow the fan to overcome its own inertia. 000 = 200 ms 001 = 400 ms 010 = 600 ms 011 = 800 ms 100 = 1 sec 101 = 2 secs (Default) 110 = 4 secs 111 = 8 secs <5:3> PWM 1 Frequency Read/Write These bits allow programmability of the nominal PWM output frequency driving the fan. (Default = 31 Hz.) 000 = 11.7 Hz 001 = 15.6 Hz 010 = 23.4 Hz 011 = 31.25 Hz (Default) 100 = 37.5 Hz 101 = 46.9 Hz 110 = 62.5 Hz 111 = 93.5 Hz <7:6> Speed Range Read/Write These bits contain the Speed Range, N. 00 = 1 (Fail Speed = 2647 RPM) 01 = 2 (Fail Speed = 1324 RPM) 10 = 4 (Fail Speed = 662 RPM) 11 = 8 (Fail Speed = 331 RPM) Table XX. Register 0x22 Fan Speed Config Register Power-On Default = 05H Bit Name R/ W Description <3:0> Normal/Min Spd 1 Read/Write This nibble contains the normal speed value for the fan. When in Automatic Fan Speed Control Mode, this nibble contains the minimum speed at which the fan will run. Default is 0x05 for 33% PWM duty cycle. (See Table VII.) <7:4> Unused Unused. Table XXI. Register 0x23 Fan Filter Register Power-On Default = 50H Bit Name R/ W Description <7> Spin-Up Disable Read/Write When set to 1, disables fan spin-up. <6:5> Ramp Rate Read/Write These bits set the ramp rate for the PWM output. 00 = 1 01 = 2 10 = 4 11 = 8 <4:2> ADC Sample Rate Read/Write These bits set the sampling rate for the ADC. 000 = 87.5 Hz 0.0625 Updates/sec 001 = 175 Hz 0.125 Updates/sec 010 = 350 Hz 0.25 Updates/sec 011 = 700 Hz 0.5 Updates/sec 100 = 1.4 kHz (Default) 1 Update/sec 101 = 2.8 kHz 2 Updates/sec 110 = 5.6 kHz 4 Updates/sec 111 = 11.2 kHz 8 Updates/sec <1> Unused Read/Write Unused. <0> Fan Filter En Read/Write Setting this bit to 1 enables filtering of the PWM_OUT signal.

REV. 0 ADM1030 –27– Table XXII. Register 0x24 Local Temp TMIN/TRANGE Power-On Default = 41H Bit Name R/ W Description <7:3> Local Temp T MIN Read/Write Contains the minimum temperature value for Automatic Fan Speed Control based on Local Temperature Readings. T MIN can be programmed to positive values only in 4°C increments. Default is 32 °C. 00000 = 0°C 00001 = 4°C 00010 = 8°C 00011 = 12°C 01000 = 32°C (Default) 11110 = 120°C 11111 = 124°C <2:0> Local Temp T RANGE Read/Write This nibble contains the temperature range value for Automatic Fan Speed Control based on the Local Temperature Readings. 000 = 5°C 001 = 10°C (Default) 010 = 20°C 011 = 40°C 100 = 80°C Table XXIII. Register 0x25 Remote Temp TMIN/TRANGE Power-On Default = 61H Bit Name R/ W Description <7:3> Remote Temp T MIN Read/Write Contains the minimum temperature value for Automatic Fan Speed Control based on Remote Temperature Readings. T MIN can be programmed to posi- tive values only in 4 °C increments. Default is 48 °C. 00000 = 0°C 00001 = 4°C 00010 = 8°C 00011 = 12°C 01100 = 48°C (Default) 11110 = 120°C 11111 = 124°C <2:0> Remote Temp T RANGE Read/Write This nibble contains the temperature range value for Automatic Fan Speed Control based on the Remote 1 Temperature Readings. 000 = 5°C 001 = 10°C (Default) 010 = 20°C 011 = 40°C 100 = 80°C

REV. 0–28– C02401–2.5–4/01(0) PRINTED IN U.S.A. ADM1030 Table XXIV. Register 0x3F Therm Behavior/Revision Power-On Default = 80H Bit Name R/ W Description <7> Therm-to-Fan En Read/Write Setting this bit to 1, enables the fan to run full-speed when THERM is asserted low. This allows the system to be run in performance mode. Clear- ing this bit to 0 disables the fan from running full-speed whenever THERM is asserted low. This allows the system to run in silent mode. (Power-On Default = 1.) Note that this bit has no effect whenever THERM is pulled low as an input. <6:4> Unused Read Only Unused. Read back zeros. <3:0> Revision Read Only This nibble contains the revision number for the ADM1030. Table XXV. Register 0x0D Local Temp Offset Power-On Default = 00H Bit Name R/ W Description <7> Sign Read/Write When this bit is 0, the local offset will be added to the Local Temperature Reading. When this bit is set to 1, the local temperature offset will be sub- tracted from the Local Temperature Reading. <6:4> Reserved Read/Write Unused. Normally read back zeros. <3:0> Local Offset Read/Write T hese four bits are used to add a two’s complement offset to the Local Temperature Reading, allowing 15 °C to be added to or subtracted from the temperature reading. Table XXVI. Register 0x0E Remote Temp Offset Power-On Default = 00H Bit Name R/ W Description <7> Sign Read/Write When this bit is 0, the remote offset will be added to the Remote Tempera- ture Reading. When this bit is set to 1, the remote temperature offset will be subtracted from the Remote Temperature Reading. <6:4> Reserved Read/Write Unused. Normally read back zeros. <3:0> Remote Offset Read/Write These four bits are used to add a two’s complement offset to the Remote Temperature Reading, allowing 15 °C to be added to or subtracted from the temperature reading. 16-Lead QSOP Package (RQ-16) 16 9 0.197 (5.00) 0.189 (4.80) 0.244 (6.20) 0.228 (5.79) PIN 1 0.157 (3.99) 0.150 (3.81) SEATING PLANE 0.010 (0.25) 0.004 (0.10) 0.012 (0.30) 0.008 (0.20) 0.025 (0.64) BSC 0.059 (1.50) MAX 0.069 (1.75) 0.053 (1.35) 0.010 (0.20) 0.007 (0.18) 0.050 (1.27) 0.016 (0.41) 8/H11543 0/H11543 OUTLINE DIMENSIONS Dimensions shown in inches and (mm).

Summary

Intelligent Temperature Monitor and PWM Fan Controller REV.0

Description