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19-2061; Rev 0; 5/01
BLE IT AVAILA LUATION K EVA
Simple, Efficient, 1-Cell Li+ Pulse Charger
General Description
The MAX1879 single-cell lithium-ion (Li+) battery charger utilizes an efficient pulse-charging architecture to minimize power dissipation in portable devices. This architecture combines the efficiency of switch-mode chargers with the simplicity and low cost of linear chargers. This simple device, in conjunction with a current-limited wall cube and a PMOS transistor, allows safe and fast charging of a single Li+ cell. The MAX1879 initiates charging in one of three ways: battery insertion, charger power-up, or toggling the THERM pin. Key safety features include continuous voltage and temperature monitoring, a preset charger time-out, and an 8mA precharge current mode to charge near-dead cells. Automatic detection of input power removal shuts down the device, minimizing current drain from the battery. An overall system accuracy of 0.75% ensures that the cell capacity is fully utilized without cycle life degradation. The MAX1879 is offered in a space-saving 8-pin MAX package. An evaluation kit (MAX1879EVKIT) is available to help reduce design time. o Simple Design Minimizes Heat o Low Component Count, No Inductor o Battery-Full Indicator o 0.75% Accurate Battery Regulation o 1.5A (max) Battery Current Drain with Wall Cube Removed o Restart Charging at 4.0V o Continuous Overvoltage and Overtemperature Protection o Safely Precharges Near-Dead Cells o Automatic Power-Down when Power Source is Removed o Charges 1 Cell from as Low as 4.5V o Pin-Compatible Upgrade to MAX1679
Features
MAX1879
Applications
Single-Cell Li+ Powered Portables Self-Charging Battery Packs PDAs Cell Phones Cradle Chargers
PART MAX1879EUA
Ordering Information
TEMP. RANGE -40C to +85C PIN-PACKAGE 8-MAX
Pin Configuration
TOP VIEW
CURRENTLIMITED AC WALL ADAPTER LED
Typical Operating Circuit
IN GATE CHG
1 2
8 7
BATT THERM GND ADJ
MAX1879
3 6 5 TSEL 4
IN CHG
GATE BATT 1-CELL Li+ BATTERY
MAX1879
PULSE WIDTH SELECT INPUT TSEL THERM THERMISTOR GND ADJ
MAX
________________________________________________________________ Maxim Integrated Products
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Simple, Efficient, 1-Cell Li+ Pulse Charger MAX1879
ABSOLUTE MAXIMUM RATINGS
IN, CHG, GATE to GND..........................................-0.3V to +26V BATT, TSEL, THERM, ADJ to GND...........................-0.3V to +6V GATE to IN................................................................-6V to +0.3V THERM, ADJ to BATT...............................................-6V to +0.3V GATE Continuous Current ................................................ -10mA Continuous Power Dissipation (TA = +70C) 8-Pin MAX (derate 4.1mW/C above +70C) ............ 330mW Operating Temperature Range ...........................-40C to +85C Storage Temperature Range ............................ -65C to +150C Lead Temperature (soldering, 10s) ................................ +300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VIN = V CHG = +10V, VBATT = +4.2V, TSEL = GND, GATE = unconnected, ADJ = unconnected, THERM = 10k to GND, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER Input Voltage (Note 1) Undervoltage Lockout Trip Point Undervoltage Lockout Trip-Point Hysteresis Fast-Charge Qualification Threshold Fast-Charge Restart Threshold Fast-Charge Reset Threshold Delay Precharge Source Current BATT Regulation Voltage BATT Regulation Adjust Range ADJ Source Impedance ADJ Output Voltage BATT Removal Detection Threshold BATT Removal Detection Threshold Hysteresis BATT Input Current (Note 4) BATT Input Current, Fast-Charge State BATT Input Current, Done State IN Input Current, Fast-Charge State IN Input Current, Done State Timer Accuracy CHG Output Leakage Current CHG Output Sink Current V CHG = 22V, CHG = high V CHG = 1.0V, CHG = low IBATT IBATT IIN IIN No load on ADJ BATT rising BATT falling VIN VBATT - 0.3V VBATT = 4.0V VBATT = 4.25V, VIN present VBATT = 4.0V, VIN = 4.0V VBATT = 4.25V, VIN = 22V -10 -1 4 5 SYMBOL VIN BATT rising BATT falling BATT rising, transition from precharge to full current BATT falling, transition from Done to Prequalification state (Note 2) (Note 3) VBATT = 2V 5 4.1685 4.0 9.8 1.393 4.875 10 1.400 5 125 0.1 900 85 50 700 1.5 1500 200 500 1200 +10 +1 6 2.425 3.92 CONDITIONS External PMOS FET off MIN 4.4 2.1 2.2 60 2.5 4.00 1 8 4.2000 12 4.2315 4.2 10.2 1.407 5.125 2.575 4.08 TYP MAX 22 2.3 UNITS V V mV V V ms mA V V k V V mV A A A A A % A mA
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Simple, Efficient, 1-Cell Li+ Pulse Charger
ELECTRICAL CHARACTERISTICS (continued)
(VIN = V CHG = +10V, VBATT = +4.2V, TSEL = GND, GATE = unconnected, ADJ = unconnected, THERM = 10k to GND, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER THERM Sense Current (for hot qualification) THERM Sense Current (for cold qualification) THERM Sense Voltage Trip Point GATE Source Current GATE Sink Current GATE Drive Current at Battery Removal VIN = 10V, VGATE = 8V VIN = 10V, VGATE = 8V VBATT = 5.1V, gate driven high SYMBOL CONDITIONS MIN 346 47.8 1.379 75 19 18 TYP 352.9 48.8 1.40 100 25 40 MAX 360 49.8 1.421 125 31 60 UNITS A A V A A mA
MAX1879
ELECTRICAL CHARACTERISTICS
(VIN = V CHG = +10V, VBATT = +4.2V, TSEL = GND, GATE = unconnected, ADJ = unconnected, THERM = 10k to GN, TA = -40C to +85C, unless otherwise noted.) (Note 5)
PARAMETER Input Voltage (Note 1) Undervoltage Lockout Trip Point Fast-Charge Qualification Threshold Fast-Charge Restart Threshold Precharge Source Current BATT Regulation Voltage BATT Regulation Adjust Range ADJ Source Impedance ADJ Output Voltage BATT Removal Detection Threshold BATT Input Current (Note 4) BATT Input Current, Fast-Charge State BATT Input Current, Done State IN Input Current, Fast-Charge State IN Input Current, Done State CHG Output Leakage Current CHG Output Sink Current IBATT IBATT IIN IIN No load on ADJ BATT rising VIN VBATT - 0.3V VBATT = 4.0V VBATT = 4.25V, VIN present VBATT = 4.0V, VIN = 4.0V VBATT = 4.25V, VIN = 22V V CHG = 22V, CHG = high V CHG = 1.0V, CHG = low -1 4 SYMBOL VIN BATT rising BATT rising, transition from precharge to full current BATT falling, transition from Done to Prequalification state (Note 2) VBATT = 2V CONDITIONS External PMOS FET off MIN 4.6 2.05 2.35 3.88 4.5 4.137 4.0 9.8 1.383 4.85 MAX 22 2.35 2.65 4.12 12 4.263 4.2 10.2 1.417 5.15 1.5 1500 300 600 1500 +1 6 UNITS V V V V mA V V k V V A A A A A A mA
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Simple, Efficient, 1-Cell Li+ Pulse Charger MAX1879
ELECTRICAL CHARACTERISTICS (continued)
(V IN = V CHG = +10V, V BATT = +4.2V, TSEL = GND, GATE = unconnected, ADJ = unconnected, THERM = 10k to GND, TA = -40C to +85C, unless otherwise noted.) (Note 5)
PARAMETER THERM Sense Current (for hot qualification) THERM Sense Current (for cold qualification) THERM Sense Voltage Trip Point GATE Source Current GATE Sink Current GATE Drive Current at Battery Removal VIN = 10V, VGATE = 8V VIN = 10V, VGATE = 8V VBATT = 5.1V, gate driven high SYMBOL CONDITIONS MIN 342 47.3 1.358 60 15 15 MAX 363 50.3 1.442 140 35 90 UNITS A A V A A mA
Note 1: The input voltage range is specified with the external PMOS FET off. When charging, the PMOS FET turns on, and the input voltage (the output voltage of the current-limited source) drops to very near the battery voltage. When the PFET is on, VIN may be as low as 2.5V. Note 2: Restart Threshold tracks battery regulation voltage adjustment. Note 3: Glitches less than 1ms do not cause a restart. Note 4: This current is less than 1.5A, even if an external RADJ resistor is connected from ADJ to GND. Note 5: Specifications to -40C are guaranteed by design and not production tested.
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Simple, Efficient, 1-Cell Li+ Pulse Charger
Typical Operating Characteristics
(VIN = CHG = +10V, VBATT = +4.2V, THERM = 10k to GND, TA = +25C, unless otherwise noted.)
MAX1879
NORMALIZED TIMER PERIOD vs. AMBIENT TEMPERATURE
MAX1879 toc01
NORMALIZED BATTERY REGULATION VOLTAGE vs. TEMPERATURE
NORMALIZED REGULATION VOLTAGE 1.0015 1.0010 1.0005 1.0000 0.9995 0.9990 0.9985 0.9980 0.9975 0.9970 NORMALIZED TO +25C
MAX1879 toc02
PRECHARGE CURRENT vs. INPUT VOLTAGE
8.8 PRECHARGE CURRENT (mA) 8.6 8.4 8.2 8.0 7.8 7.6 7.4 7.2 7.0 VBATT = 2V VBATT = 0
MAX1879 toc03
1.020 1.015 NORMALIZED TIMER PERIOD 1.010 1.005 1.000 0.995 0.990 0.985 0.980 -40 -20 0 20 40 TEMPERATURE (C) 60 80 NORMALIZED TO +25C
1.0020
9.0
-40
-20
0 20 40 TEMPERATURE (C)
60
80
5
10
15 VIN (V)
20
25
Pin Description
PIN 1 2 NAME IN GATE FUNCTION Input Voltage from Current-Limited Voltage Source (+22V max). Bypass to GND with a 0.1F capacitor. Gate Drive for External PMOS Pass Element. The PMOS device should have a VGS threshold less than 2.5V. See Selecting External Components. Charge Status Indication. A CHG low indicates that the MAX1879 is charging a battery. CHG goes high when the on/off duty cycle falls to 1/8, indicating that the battery is charged to approximately 95% of full capacity. CHG is an open-drain current-limited N-channel MOSFET suitable for directly driving an LED. Connect a pullup resistor to the logic supply to generate a logic-level signal. CHG blinks at 2Hz during the Prequalification state (2.2V < VBATT < 2.5V) and during a temperature fault. Minimum ON/OFF Pulse Width Selection (Table 2) Battery Regulation Voltage Adjustment. Bypass to GND with a 1000pF capacitor. Connect a resistor from ADJ to GND to reduce the nominal +4.200V regulation set point. See Adjusting the Battery Regulation Voltage. Ground. See Layout Guidelines for information on system grounding. Connect the battery's negative terminal to GND. Thermistor Temperature-Sensor Input. Connect an NTC thermistor (10k at +25C) from THERM to GND to allow prequalification of the cell temperature for fast-charge. Replace the thermistor with a 10k resistor if temperature sensing is not required. Cell Voltage Monitor Input, Precharge Current Output, and MAX1879 Power Source. Connect BATT to the positive terminal of a single Li+ cell. Bypass BATT with a capacitor to ground (1.5F per amp of charge current).
3
CHG
4 5
TSEL ADJ
6
GND
7
THERM
8
BATT
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Simple, Efficient, 1-Cell Li+ Pulse Charger MAX1879
Functional Diagram
CURRENT-LIMITED VOLTAGE SOURCE (800mA)
PFET REVERSE-CURRENT PROTECTION DIODE IN GATE
MAX1879
PRECHARGE CURRENT (8mA) 5mA
CHG
BATT 10k TSEL SEE TABLE 2 FOR PULSE-WIDTH OPTIONS TIMER STATE MACHINE 1.4V RADJ ** SINGLE Li+ CELL 1:3 ADJ 2.2F
1nF BATT REMOVED 5V
30kHz OSCILLATOR HOT QUAL TEST CURRENT
COLD QUAL TEST CURRENT
1.4V
THERM
NTC THERMISTOR*
*OPTIONAL--REPLACE WITH 10k RESISITOR IF NOT SENSING TEMPERATURE. **RADJ = 410k 1% FOR 4.1V CELL; LEAVE OPEN FOR 4.2V CELL.
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Simple, Efficient, 1-Cell Li+ Pulse Charger
Simplified State Diagram
CHARGING POWER REMOVED (FROM ANY STATE) SHUTDOWN PMOS FET: OFF LED: OFF CHARGING POWER APPLIED VBATT < 4.0V OR PULL THERM HIGH
MAX1879
VBATT > 2.2V
POWER-ON RESET 8.0mA PRECHARGE: ON PMOS FET: OFF LED: OFF
BATT NOT INSTALLED OR VBATT < 2.2V (ASYNCHRONOUSLY, FROM ANY STATE)
PREQUALIFICATION 8.0mA PRECHARGE: ON PMOS FET: OFF LED: 50% DUTY CYCLE, 2Hz TEMPERATURE NOT OK OR VBATT < 2.5V 2.5V < VBATT < 4.2V VBATT 4.2V
VBATT < 2.5V
VBATT > 4.0V DONE PMOS FET: OFF LED: OFF
CHARGE PMOS FET: PULSED LED: ON EVERY 9s TEMPERATURE OK VBATT < 2.5V CHARGE QUALIFICATION PMOS FET: OFF LED: ON BATT REGULATION VOLTAGE (e.g., 4.2V) HAS BEEN REACHED AND FET ON-TIME < 1 FET OFF-TIME 8
TEMPERATURE NOT OK (LED: 50% DUTY CYCLE, 2Hz) EVERY 9S
TOP-OFF PMOS FET: PULSED LED: OFF
TOTAL TIME = 6.25hr
TEMPERATURE OK VBATT < 2.5V TOP-OFF QUALIFICATION PMOS FET: OFF LED: OFF
TEMPERATURE NOT OK (LED: OFF)
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Simple, Efficient, 1-Cell Li+ Pulse Charger MAX1879
Detailed Description
Initiating a Charge Cycle
The MAX1879 initiates fast-charge upon insertion of a battery or application of an external power source (current-limited AC wall adapter). After charge completion, charging restarts if the cell voltage falls below 4.0V or when THERM is pulled above 1.4V after the charge timer expires (approximately 6.25hr). Before a charge cycle can begin, cell conditions are verified to be within safe limits. The cell voltage must be greater than 2.5V but less than the regulation voltage (default value 4.2V). In addition, the thermistor must indicate an acceptable cell temperature (default range +2.5C to +47.5C). See the Applications Information section. Li+ cells can be damaged when fast-charged from a completely dead state. Moreover, a fully discharged cell may indicate a dangerous abnormal cell condition. As a built-in safety feature, the MAX1879 precharges the Li+ cell with 8mA at the start of a charge cycle if the cell voltage is below 2.5V. As soon as the cell reaches 2.5V and the safety conditions are met (see the FastCharge section), fast-charging begins. If the temperature moves outside the programmed range, the charger pauses. When the temperature returns to the safe charging range, the charging cycle continues, and the charge timer resumes counting from the point at which the temperature fault occurred. The timer is not reset. The MAX1879 monitors these conditions throughout the charging cycle. tery-voltage sensing errors due to charging current flowing through the series resistance of cell protection switches or fuse links in the charging path. Fast-charge continues until the on/off duty cycle falls to 1/8, then the CHG LED turns off, indicating that the battery is charged to approximately 95% of full capacity.
Pulsed Top-Off Charge
At the beginning of the Top-Off state, the current stays on for a 1/8 duty cycle. As the cell continues to charge, the percentage of time spent in the "current-on" mode decreases. Towards the end of top-off, the current stays off for many cycles between single "on" pulses. During these final pulses, the instantaneous cell voltage may exceed the battery regulation voltage, but the duration of these pulses is several orders of magnitude shorter than the intrinsic chemical time constant of the Li+ cell. This does not harm the cell. Cell top-off is completed when the charging timer expires (approximately 6.25hr).
Charge Status with CHG
CHG indicates the cell's charging status. An LED can be connected directly from IN to CHG for a visible indicator. Alternatively, a pullup resistor (100k) from a logic supply to CHG provides a logic-level output. Table 1 relates the LED status to the charger condition.
Applications Information
The MAX1879 was designed to offer the maximum integration and functionality in the smallest, most basic application circuit possible. The only necessary external components are a current-limited wall cube, a PMOS FET, two small capacitors, and a 10k thermistor/resistor. This simple application circuit appears in Figure 1. Optionally (as shown in Figure 2), an LED can be added as a charge-state indicator, a resistor (RADJ) can be used to trim down the maximum charge voltage
Fast-Charge
Once cell conditions are determined to be satisfactory, the MAX1879 fast-charges the Li+ cell by pulling GATE low, turning on the external PMOS FET. Cell charging current is set by the current limit of the external power supply; it is not regulated by the MAX1879. The PMOS FET operates only as a switch, not as a linear regulator. Therefore, power dissipation is minimized, permitting rapid charge cycles with minimal heat generation. The external power supply must have a specified current limit that matches the desired fast-charge current for the Li+ cell. The MAX1879 uses a hysteretic algorithm with minimum on-times and minimum off-times to top-off the cell. The cell voltage is sampled every 2ms. If VBATT is less than the battery regulation voltage, the external PMOS FET turns on or remains on. If the cell voltage is greater than or equal to the battery regulation voltage, the FET turns off and remains off for the minimum off-time. By measuring the cell voltage when the PMOS FET is off as well as when it is on, the MAX1879 eliminates bat8
Table 1. CHG Output States
CONDITION No battery or no charger, or cell voltage < 2.2V Fast-charge in progress Top-Off: on/off duty cycle < 1/8 Done (charge complete) Temperature fault Prequalification (2.2V < VBATT < 2.5V) CHG (LED) High impedance (LED off) Low (LED on) High impedance (LED off) High impedance (LED off) LED blinks at 2Hz LED blinks at 2Hz
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Simple, Efficient, 1-Cell Li+ Pulse Charger
from 4.2V, and/or a reverse-current-protection diode can be added in line at the source. If the input is shorted, the MAX1879 will not allow current to flow from BATT back through IN to the source. However, the body diode inherent in the enhancementmode FET would still allow the cell to discharge rapidly. To prevent this, add a power Schottky diode between the source and IN as in Figure 4. Therefore, the additional system error is simply the RADJ tolerance multiplied by the percent change in the battery regulation voltage, or (1%)(2.4%) = 0.024%.
MAX1879
Selecting Minimum On-Time
The minimum pulse on-times can be selected by connecting TSEL as indicated in Table 2. A short pulse time may be preferred to minimize voltage overshoot at the battery and prevent pack overvoltage protection circuitry from prematurely activating. A long minimum on-time may be needed when using AC adapters with high turn-on overshoot to allow charging current to settle before the end of the pulse.
Adjusting the Battery Regulation Voltage
A typical Li+ cell should be charged at a constant current until it reaches a voltage of about 4.2V, then charged at this voltage until the current decays below a predetermined level. The MAX1879 provides a simple way to reduce this maximum target voltage with a single resistor between ADJ and GND. Internally, ADJ connects to a precision 1.4V reference through a 10k resistor. Leave ADJ open for a battery regulation voltage (VBR) of 4.2V; connect a 1% resistor from ADJ to GND to form a voltage-divider for lower battery regulation voltage (VBR). Select the external value using: RADJ = 10k VBR -1 VBR
Selecting External Components
Power Supply One reason the MAX1879 Li+ cell-charging solution is so compact and simple is that the charging current is set by the external power source, not by the MAX1879 charging circuit. The PMOS FET in this application circuit is either on or off, allowing the source to be directly connected to the cell or completely disconnected. Therefore, it is very important to choose a power supply
Table 2. TSEL Minimum On-Time Settings
TSEL CONNECTION BATT ADJ GND MINIMUM ON-TIME IN TOP-OFF (ms) 34 69 137
A 1% tolerance resistor at ADJ degrades system accuracy by only a fraction of a percent. For example, an RADJ of 410k 1% reduces the battery regulation voltage by 2.4% (VBR = 4.1V from equation above, and (VBR - VBR) / VBR = (4.1 - 4.2) / 4.2 = -2.4%).
CURRENT-LIMITED WALL CUBE (800mA, 6V max)
PMOS FET FAIRCHILD FDC638P -4.5A, -20V 0.07 AT VGS = -2.5V
CURRENT-LIMITED SCHOTTKY DIODE 30V, 1A WALL CUBE ZETEX ZHCS1000 (800mA, 6V max)
PMOS FET FAIRCHILD FDC638P -4.5A, -20V 0.07 AT VGS = -2.5V GATE
GATE IN IN MAX1879 TSEL* ADJ THERM 10k 2.2F SINGLE Li+ CELL 0.001F BATT 5mA LED CHG CHG 0.001F RADJ 410k 1%** MAX1879 BATT SINGLE Li+ CELL
TSEL* ADJ THERM 2.2F NTC THERMISTOR FENWAL 140-103LAG-RBI (10k AT 25C)
*SEE TABLE 2 FOR TSEL POSITION AND ASSOCIATED TIMER SETTINGS.
*SEE TABLE 2 FOR TSEL POSITION AND ASSOCIATED TIMER SETTINGS. ** RADJ SETS BATTERY REGULATION VOLTAGE TO 4.10V; LEAVE OPEN FOR 4.2V.
Figure 1. Simple Application Circuit
Figure 2. Application Circuit Including LED and Thermistor 9
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Simple, Efficient, 1-Cell Li+ Pulse Charger MAX1879
with current limiting. In most applications, this will be a small "wall cube" switching converter with an output voltage limit of about 5V or 6V, which is specified as "current-limited" or "constant current." PMOS Switch The PMOS FET switches the current-limited source on and off. Because of the intentionally slow switching times and limited slew rate, the MAX1879 is not particular about the power FET it drives. Specifications to consider when choosing an appropriate FET are the minimum drain-source breakdown voltage, the minimum turn-on threshold voltage (VGS), and current-handling and power-dissipation qualities. The minimum breakdown voltage (BVDS) must exceed the open-circuit voltage of the wall cube by at least 25%. Note that this open-circuit voltage may be twice as high as the specified output voltage, depending on the AC adapter type. Thermistor The intent of THERM is to inhibit fast-charging the cell when it is too cold or too hot (+2.5C TOK 47.5C), using an external thermistor. THERM time multiplexes two sense currents to test for both hot and cold qualification. The thermistor should be 10k at +25C and have a negative temperature coefficient (NTC); the THERM pin expects 3.97k at +47.5C and 28.7k at +2.5C. Connect the thermistor between THERM and GND. If no temperature qualification is desired, replace the thermistor with a 10k resistor. Thermistors by Philips (22322-640-63103), Cornerstone Sensors (T101D103-CA), and Fenwal Electronics (140-103LAGRB1) work well. Bypass Capacitors Bypass the ADJ pin with a 2000pF ceramic capacitor. Bypass BATT with a capacitor with a value of at least 1.5F per amp of charge current. The MAX1879 has a built-in protection feature that prevents BATT from rising above 5.5V. The device recognizes a rapid rise at BATT, indicating that the cell is being removed with the FET on. A capacitor from BATT to GND that's too small does not give the MAX1879 adequate time to shut off the FET. BATT may then rise above 6V (towards the open-circuit source voltage), violating the absolute maximum rating and damaging the device. In applications where the cell is removable, very large capacitance values make it increasingly difficult to identify momentary cell removal events and may increase transient currents when the cell is replaced. Therefore, values in excess of 100F should be avoided in those cases. For best system performance, at least 0.47F of the total capacitance should be low-ESR ceramic.
Layout Guidelines
The MAX1879 controls the GATE slew rate. The layout is not as sensitive to noise as a high-frequency switching regulator. In addition, since the cell voltage is sensed both during and between high-current pulses, the system is insensitive to ground drops. However, Maxim recommends establishing good grounding areas and large traces for high-current paths.
Chip Information
TRANSISTOR COUNT: 4692 SUBSTRATE CONNECTED TO GND
10
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Simple, Efficient, 1-Cell Li+ Pulse Charger
Package Information
8LUMAXD.EPS
MAX1879
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 11 (c) 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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