34674 FREESCALE | Alldatasheet
Document overview
- Manufacturer or author: Provided By alldatasheet.com(free datasheet download site)
- PDF pages: 26
Technical content
Features
- No external MOSFET, reverse-blocking diode or current- sense resistor are required
- 2 8 V maximum input voltage rating with 11 V over-voltage protection threshold
- Factory programmable charge current
- Trickle charge for fully discharged batteries
- ±0.4% voltage accuracy over -20°C to 70°C
- Driving a dual-color LED and smart battery connection verification optimized for travel charger applications
- Interface to NTC thermistor
- Internal timer and thermal current limit
- Small 2X3 mm 2 thermally enhanced UDFN package
- Pb-free packaging designated by suffix code EP
Figure 1. 34674 Simplified Application Diagram
ORDERING INFORMATION
Range (TA) Package Refer to Table 1, Device Variations -40°C to 85°C 8 UDFN-EP VIN GND RED GRN EN BAT VREF TEMP RPU 34674 RS VIN TO BATTERY TO BATTERY NTC (THERMISTOR) CIN COUT ON OFF
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- Freescale offers a series of MC34674 variat ions. Each variation has an increment of 50 mA or 100 mA for the CC-mode current.
Table 1. Device Variations
Figure 2. 34674 Simplified Internal Block Diagram
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Figure 3. 34674 Pin Connections Table 2. 34674 Pin Definitions A functional description of each pin can be found in the Functional Pin Description section beginning on page 12. 1 VIN Input Input supply The supply input. 2 GRN Output Green indicator Indication of the charge status. Open drain output with 6 mA current limit. 3 RED Output Red indicator Indication of the charge status. Open drain output with 6 mA current limit. 4 EN Input Enable Active-low enable logic input. 6 TEMP Input NTC interface input The NTC thermistor interface pin.
7 VREF Output NTC interface bias
The bias voltage for the NTC interface circuit. 8 BAT Output Charger output The charger output pin to the battery. the large ground plane on the PCB to increase the thermal dissipation. The pad must be connected to GND electrically.
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ELECTRICAL CHARACTERISTICS
Table 3. Maximum Ratings permanent damage to the device.
- ESD testing is performed in accordance with the Human Body Model (HBM) (C ZAP = 100 pF, RZAP = 1500 Ω), and the Machine Model
- Device mounted on the Freescale EVB test board per JEDEC DESD51-2.
- Pin soldering temperature limit is for 10 seconds maximum dura tion. Not designed for immersion soldering. Exceeding these limits may
cause malfunction or permanent damage to the device.
- Freescale’s Package Reflow capability meets Pb-free requirements for JEDEC standard J-STD-020C. For Peak Package Reflow
and enter the core ID to view all orderable parts. (i.e. MC33xxxD enter 33xxx), and review parametrics.
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STATIC ELECTRICAL CHARACTERISTICS STATIC ELECTRICAL CHARACTERISTICS Table 4. Static Electrical Characteristics
- Refer to the Power-on-Reset parameter for V IN turn on and turn off values.
- Supply current does not include the current delivered to the battery through the BAT pin.
- In the test mode, the charger still operates in CV mode after EOC.
- Characterized over the temperature range -40°C ≤ TA ≤ 85°C
Analog Integrated Circuit Device Data Freescale Semiconductor 7 34674 STATIC ELECTRICAL CHARACTERISTICS End-of-Charge (EOC) Threshold MC34674A MC34674B MC34674C MC34674D IEOC 105 126 102 mA CHARGE THRESHOLDS Trickle-mode Rising Threshold Voltage VTRKL 2.8 2.9 3.0 V Trickle-mode Threshold Voltage Hysteresis VTRKLHYS - 100 - mV Recharge Falling Threshold Voltage VRECH 4.07 4.10 4.135 V Recharge Threshold Voltage Hysteresis VTHRCHG - 25 50 mV BATTERY CONNECTION VERIFICATION Output Current in Charge Completion State(10) ICHGCM - 24 - μA Discharge Current in Charge Completion State During the 82 ms(10) IDCC - 585 - μA NTC INTERFACE Low Temperature Rising Threshold(11) VLTRT 0.6592 2/3 0.6741 VREF Low Temperature Falling Threshold(11) VLTFT - 0.6468 - VREF High Temperature Falling Threshold(11) VHTFT 0.3297 1/3 0.3389 VREF High Temperature Rising Threshold(11) VHTRT - 0.3441 - VREF Die Thermal Limit TLIM 95 110 125 °C LOGIC INPUT AND OUTPUT EN Input High Threshold Voltage VIH 1.5 - - V EN Input Low Threshold Voltage VIL - - 0.5 V EN Pin Internal Pull-down Current IEN - 2.0 7.5 μA GRN and RED Sink Current Pin voltage is between 0.8 V and 5.0 V IGRSINK 5.0 6.0 7.0 mA Open-Drain Off Leakage Biased at 5.0 V IODLEAK - - 1.0 μA Notes 10. Not tested . Guaranteed by design. 11. These threshold parameters are specified as a ratio of V TEMP/VREF. Due to the negative temperature coefficient thermistor, VTEMP rises when the temperature is falling from high to low, and VTEMP falls when the temperature is rising from low to high. Table 4. Static Electrical Characteristics (continued)
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DYNAMIC ELECTRICAL CHARACTERISTICS DYNAMIC ELECTRICAL CHARACTERISTICS Table 5. Dynamic Electrical Characteristics
- Not tested. Guaranteed by design.
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ELECTRICAL PERFORMANCE CURVES Figure 10. VBAT vs Temperature Figure 11. Constant Charge Current vs Temperature Figure 12. Trickle Charge Current vs Temperature Figure 13. RDS(ON) vs Temperature Figure 14. Recharge Voltage Threshold vs Temperature Figure 15. BAT Pin Supply Current vs Temperature
Analog Integrated Circuit Device Data Freescale Semiconductor 11 34674 ELECTRICAL PERFORMANCE CURVES Figure 16. VIN Pin Supply Current vs Temperature
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a current-limited AC/DC output for minimum heat generation. safety, and smart battery connection verification. power status and the charge status to users via LEDs. Figure 17. Charge Profile Open-drain logic output to indicate the charging status. with an internal 6.0 mA current source. Open-drain logic output to indicate the charging status. with an internal 6.0 mA current source. externally disables the charger. resistor is required between the TEMP pin and VREF pin. To supply bias voltage for the NTC interface circuit. conductivity. The pad must be connected to GND electrically.
Figure 18. 34674 Functional Internal Block Diagram voltages for other functional blocks. indicate the end of the charge. current to prevent further temperature rise. to set the charge temperature window.
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FUNCTIONAL INTERNAL BLOCK DESCRIPTION LOGIC LOGIC CONTROL AND STATUS INDICATION The logic control block determines the on and off states of the charger. It takes the signals from the VIN Monitor, VIN- BAT comparator, EOC, NTC interface blocks, and the external enable signal EN, and determines the on and off states as well as the charge status indication outputs of the charger. This block also contains the logic circuit for the battery connection verification and the internal timer. POWER MOSFET The power MOSFET passes the charging current from the input to the output.
describes each state in detail. ideal for working with a current-limited AC/DC converter. both colors). Each color is on for 0.5 seconds. disabled and stays in the Enable Verification state. charger will detect it and enter the trickle-charge mode. Table 6. Consult Freescale for values that are not Table 6. Customer Selectable CC-Mode Current Values. enters the charge completion state. The LED indicates the red color in the fast charge mode.
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FUNCTIONAL DEVICE OPERATION current needs to stay below the EOC threshold for more than 0.5 seconds. The charger is turned off and the LED indication is green when charge completes. If the total fast charge time limit is exceeded, the charger also enters the charge completion state. RECHARGE MODE If the battery voltage drops below the recharge threshold after charge completion, the charger will try to recharge the battery to 4.2 V. Because the battery voltage drop can also be caused by the removal of the battery, before starting recharge, the charger tries to verify if the battery is still present. If the battery is not found, then the connection fault is issued again. If the battery is still connected, the charger restarts charging to bring the battery to a full state. The LED indication remains green in this mode. The recharge mode has the same total charge time limit as the fast charge mode. For any reason the battery voltage falls below the trickle-charge threshold in the recharge mode, the charger will enter the battery connection verification state again, as shown in Figure 23. TEMPERATURE AND OVER-VOLTAGE FAULT The NTC interface block offers an interface to an external NTC thermistor circuit to monitor the battery temperature. When the battery temperature is out of a user-programmable window, the charger is disabled and a fault condition is issued with a yellow LED indication. When the fault conditions are removed, the charger enters the battery connection verification state. More detailed description on the NTC interface is offered later in this datasheet. The charger has an 11 V (typ.) input OVP threshold. When the input voltage is higher than this threshold, the charging is stopped and a fault condition is issued with a yellow LED indication. When the input voltage falls below the OVP threshold, the charger restarts charging and resets the internal digital logic control block. TIMEOUT FAULT The TIMEOUT fault can only occur when the charger stays in the trickle-charge mode for a period longer than the time limit. The charger is turned off and a yellow LED indication is issued when this fault occurs. The only path to exit this fault is by toggling the EN input or by recycling the power input. DETAILED FUNCTIONAL DEVICE OPERATION NTC INTERFACE The MC34674 offers an interface to an external NTC thermistor to monitor the battery temperature. The low and high temperature thresholds in the Table 4 allow users to set a temperature window (such as 0°C to 50°C), within which the charging is allowed. If the battery temperature is out of such a window, a temperature fault is issued and the LED indicates a yellow color. Figure 19 shows the internal equivalent circuit for the NTC interface and the external NTC thermistor circuit. An internal resistor divider that is powered by the VREF pin voltage, VVREF, creates two reference voltages, 1/3 VVREF and 2/3 VVREF. An external resistor divider also powered by VVREF generates the voltage VTEMP to represent the battery temperature. Because the resistance of the NTC thermistor, RNTC, decreases as temperature rises, as shown in Figure 20, VTEMP decreases as the battery temperature increases. Assume TCOLD and THOT are the two temperature thresholds, such as 0°C and 50°C. When the battery temperature falls below T COLD, VTEMP rises above 2/3 VVREF and an under-temperature fault is issued. Similarly, when the battery temperature rises above THOT, VTEMP falls below 1/3 VVREF, so an over-temperature fault is issued. The relationship between the internal and the external divider voltages at the triggering points can be expressed as the following: equ. 1 where RNTC is the thermistor resistance at the given temperature, and KX is the ratio of the internal divider at the given triggering points (see Table 4). RU and RS represent a pull-up resistor and a series resistor in the external resistor divider respectively. The resistance selection of RU and RS can be figured out by the following two equations: equ. 2 equ. 3 where KHOT and KCOLD are the resistor divider ratios for the temperature thresholds THOT and TCOLD respectively; RHOT and RCOLD are the NTC thermistor resistance at THOT and TCOLD respectively. The typical values for KHOT and KCOLD are 1/3 and 2/3 respectively, as given in Table 4. Refer to the Application Information section for more details regarding the RU and RS selection. RNTC RS+ RHOT RS+ RCOLD RS+
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cannot change very fast when being charged or discharged. a 24 μA current to the output during the whole 1.968 seconds. Figure 22. Simplified Battery Removal Detection Circuit. reduce the charge current to prevent further temperature rise. the concern of thermal failure. in. Consult Freescale for additional indication schemes. to the Typical Applications section for more details.
Figure 23. 34674 Flow Chart
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regulator whose output current is limited to a value lower. section is the application information. outputs a no load voltage, VNL, when the supply is not loaded. limited by the dotted lines. current-limited regulator is dependent on the battery voltage. MC34674 operates same as a regular linear charger. Figure 24. AC/DC Regulator Output I/V Characteristics. Figure 25. AC/DC Regulator Output and MC34674 Figure 26. Charging Waveforms When Powered with
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APPLICATIONS
The two equations (equ. 2 and equ. 3) on page 16 can be further simplified as the following by substituting the KHOT and KCOLD with their typical values: equ. 4 equ. 5 The RS equation requires otherwise, the RS calculation results in a negative value. Assuming the target temperature window is from 0°C to 50°C, from Table 7 it can be found that RHOT = 33.1946 kΩ and RCOLD = 357.0117 kΩ. Using equ. 4 and equ. 5, one can find that Temperature Hysteresis The thermistor resistance can be found with equ. 1 on page 16, which can be simplified as equ. 6 Since the RS and RU have already been determined, the thermistor resistance can be found by replacing the KX with the Low Temperature Falling Threshold and the High Temperature Rising Threshold given in Table 4. The thermistor resistance at these two thresholds can be found as From Table 7 it is found that rising threshold for the cold temperature is about 2°C and the falling threshold for the hot temperature is between 46 to 47°C. Therefore the hystereses for the cold and the hot temperature is 2°C and 2 to 3°C respectively. Temperature Tolerance The equ. 6 is also the basis for tolerance calculation. The errors of the internal voltage thresholds, external resistors and the thermistor resistance all contribute to the temperature error. For the low temperature threshold, TCOLD, the maximum thermistor resistance happens when the internal threshold is at its maximum, R U at its maximum and the RS at its minimum value. Assuming 1% accuracy for both RU and RS and taking the maximum value for the low temperature threshold from Table 4, the maximum thermistor resistance at the cold temperature is found to be = equ. 7 = 377.0kΩ which corresponds to -1.4°C in the R-low column of Table 7. Similarly, the minimum thermistor resistance at the hot temperature, RHOT,MIN, happens when the internal threshold is at its minimum, RU at this minimum, and the RS at its maximum. Using the same method, the RHOT,MIN can be found to be 29.73 kΩ, which corresponds to 53°C approximately. Based on the above calculation, the tolerances for the cold and the hot temperatures are about 1.4°C and 3°C respectively. ESD ENHANCEMENT All pins in the MC34674 are rated 2.0 kV for the ESD performance with the Human Body Model (HBM). The end product usually requires higher ESP performance for the nodes that can be touched by human hands in normal usage of the end product. Three additional capacitors can be used to pass the ESD tests. Figure 28 shows how the three capacitors (C3, C4, and C5) are connected in the circuit. Figure 28. 34674 Typical Application Circuit
Analog Integrated Circuit Device Data Freescale Semiconductor 23 34674 PACKAGING PACKAGING DIMENSIONS PACKAGING PACKAGING DIMENSIONS For the most current package revision, visit www.freescale.com and perform a keyword search using the “98A” listed below. EP SUFFIX 8-PIN 98ASA10774D REVISION 0
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Analog Integrated Circuit Device Data Freescale Semiconductor 25 34674
REVISION HISTORY
REVISION DATE DESCRIPTION OF CHANGES 1.0 1/2007 • Initial Release 2.0 11/2008 • Updated Freescale form and style
- Added Device Variations
- Made corrections to coincide with Device Variation table
Rev. 2.0 Information in this document is provided solely to enable system and software implementers to use Freescale Semiconductor products. There are no express or implied copyright licenses granted hereunder to design or fabricate any integrated circuits or integrated circuits based on the information in this document. Freescale Semiconductor reserves the right to make changes without further notice to any products herein. Freescale Semiconductor makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Freescale Semiconductor assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters that may be provided in Freescale Semiconductor data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals”, must be validated for each customer application by customer’s technical experts. Freescale Semiconductor does not convey any license under its patent rights nor the rights of others. Freescale Semiconductor products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the Freescale Semiconductor product could create a situation where personal injury or death may occur. Should Buyer purchase or use Freescale Semiconductor products for any such unintended or unauthorized application, Buyer shall indemnify and hold Freescale Semiconductor and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that Freescale Semiconductor was negligent regarding the design or manufacture of the part. Freescale™ and the Freescale logo are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc., 2007-8. All rights reserved. How to Reach Us: Home Page: www.freescale.com Web Support: http://www.freescale.com/support USA/Europe or Locations Not Listed: Freescale Semiconductor, Inc. Technical Information Center, EL516
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