Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - battery management Charge management NiCd, NiMH QSOP 16 Surface-mount

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EVALUATION KIT AVAILABLE

Functional Diagrams

Pin Configurations appear at end of data sheet.

Functional Diagrams continued at end of data sheet.

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_______________General Description

The MAX1640/MAX1641 CMOS, adjustable-output,

switch-mode current sources operate from a +5.5V to

+26V input, and are ideal for microprocessor-controlled

battery chargers. Charging current, maximum output

voltage, and pulse-trickle charge are programmed with

external resistors. Programming the off-time modifies

the switching frequency, suppressing undesirable har-

monics in noise-sensitive circuits. The MAX1640’s high-

side current sensing allows the load to connect directly

to ground, eliminating ground-potential errors. The

MAX1641 incorporates a low-side current sense.

The MAX1640/MAX1641 step-down pulse-width-modu-

lation (PWM) controllers use an external P-channel

MOSFET switch and an optional, external N-channel

MOSFET synchronous rectifier for increased efficiency.

An internal low-dropout linear regulator provides power

for the internal reference and circuitry as well as the

gate drive for the N-channel synchronous rectifier.

The MAX1640/MAX1641 are available in space-saving,

16-pin narrow QSOP packages.

________________________Applications

Battery-Powered Equipment

Laptop, Notebook, and Palmtop Computers

Handy Terminals

Portable Consumer Products

Cordless Phones

Cellular Phones

PCS Phones

Backup Battery Charger

____________________________Features

♦ 95% Efficiency

♦ +5.5V to +26V Input Supply Range

♦ 2V to 24V Adjustable-Output Voltage Range

♦ 100% Maximum Duty Cycle (Low Dropout)

♦ Up to 500kHz PWM Operation

♦ Optional Synchronous Rectifier

♦ 16-Pin QSOP Package

♦ Current-Sense Accuracy: 2% (MAX1641)

5.3% (MAX1640)

Adjustable-Output, Switch-Mode

Current Sources with Synchronous Rectifier

__________________ Pin Configuration

LDOL IN

LDOH

PDRV

NDRV

PGND

CS+

CS-

GND

TOP VIEW

MAX1640

MAX1641

QSOP

TOFF

REF

SET

TERM

19-1245; Rev 2; 5/09

PART

MAX1640C/D

MAX1640EEE+

MAX1641C/D

0°C to +70°C

-40°C to +85°C

0°C to +70°C

TEMP RANGE PIN-PACKAGE

Dice*

16 QSOP

Dice*

______________Ordering Information

*Dice are specified at T

= +25°C, DC parameters only.

+Denotes a lead(Pb)-free/RoHS-compliant package.

MAX1641EEE+ -40°C to +85°C 16 QSOP

IN LDOH

PDRV

NDRV

PGND

CS+

CS-

TERM

LDOLGND

OUT

= +5.5V TO +26V

TOFF

REF

SET

MAX1640

__________Typical Operating Circuit

MAX1640/MAX1641

Summary of content (12 pages)

PAGE 1
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PAGE 2
MAX1640/MAX1641 Adjustable-Output, Switch-Mode Current Source with Synchronous Rectifier ABSOLUTE MAXIMUM RATINGS IN to GND ...............................................................-0.3V to +28V LDOH to IN ...............................................................+0.3V to -6V LDOL to GND ...........................................................-0.3V to +6V PDRV to GND .............................. (VLDOH - 0.3V) to (VIN + 0.3V) NDRV to GND .........................................-0.
PAGE 3
MAX1640/MAX1641 Adjustable-Output, Switch-Mode Current Source with Synchronous Rectifier ELECTRICAL CHARACTERISTICS (continued) (VIN = +12V, VOUT = 6V, Circuit of Figure 1, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER PWM Maximum Duty Cycle Input Low Voltage Input High Voltage Input Leakage Current SYMBOL CONDITIONS MIN TYP MAX 100 VIL VIH IIN D0, D1 D0, D1 D0, D1 UNITS ±1 % V V µA MAX UNITS 5.5 26 V 0.8 2.
PAGE 4
MAX1640/MAX1641 Adjustable-Output, Switch-Mode Current Source with Synchronous Rectifier __________________________________________Typical Operating Characteristics (Circuit of Figure 1, TA = +25°C, unless otherwise noted.) 60 1.490 TA = +85°C 1.480 TA = +25°C 40 4 6 8 10 12 14 16 18 20 22 24 MAX1640/41-TOC03 1.480 1.470 TA = +25°C 1.450 4 8 12 16 20 24 2 28 4 6 8 10 12 14 16 18 20 22 24 INPUT VOLTAGE (V) OUTPUT VOLTAGE (V) MAX1641 OUTPUT CURRENT vs.
PAGE 5
MAX1640/MAX1641 Adjustable-Output, Switch-Mode Current Source with Synchronous Rectifier ____________________________Typical Operating Characteristics (continued) (Circuit of Figure 1, TA = +25°C, unless otherwise noted.
PAGE 6
MAX1640/MAX1641 Adjustable-Output, Switch-Mode Current Source with Synchronous Rectifier _________________________________________________________ Functional Diagram IN LDOL LDOH REG A1 CS+ PDRV A2 Gm CS- MODE CONTROL SET B NDRV MUX PGND REF A SEL MAX1640 MAX1641 TERM D0, D1 6 CC TOFF Maxim Integrated
PAGE 7
MAX1640/MAX1641 Adjustable-Output, Switch-Mode Current Source with Synchronous Rectifier 0.33μF 47μF 4.7μF IN LDOH LDOL PDRV 0.33μF 47μF 1/2 IR7309 IN P LDOL 0.1μF 4.7μF 1/2 IR7309 LDOH PDRV P 0.1μF MAX1641 D0 MAX1640 D0 D1 D1 RTOFF RTOFF TOFF 1/2 IR7309 NDRV TOFF N 1/2 IR7309 47μH NDRV REF N VOUT PGND REF BATT 47μH PGND R3 R1 CS+ CS+ R1 SET 0.1μF 100mΩ R4 R2 CS- 100mΩ SET 0.1μF R2 CSVOUT R3 TERM CC BATT GND TERM CC 0.01μF GND R4 0.01μF Figure 1a.
PAGE 8
MAX1640/MAX1641 Adjustable-Output, Switch-Mode Current Source with Synchronous Rectifier The voltage at SET is given by: R1 = R2 (VREF / VSET -1 ); 10kΩ < R2 < 300kΩ where V REF = 2V and V SET is proportional to the desired output current level. L MAX1641 BATT Table 1. Selecting Output Current Levels D1 DO MODE OUTPUT CURRENT (A) 0 0 OFF 0 1 Top-Off VSET / (13.3RSENSE) 1 0 Pulse-Trickle VSET / (13.3RSENSE) 12.5% duty cycle 1 1 Fast Charge VREF / (13.
PAGE 9
MAX1640/MAX1641 Adjustable-Output, Switch-Mode Current Source with Synchronous Rectifier where V TERM = 2V and V OUT is the desired output voltage. generating increased ripple at the output. Select CCC to optimize the ripple vs. loop response. Programming the Off-Time Synchronous Rectification When programming the off-time, consider such factors as maximum inductor current ripple, maximum output voltage, inductor value, and inductor current rating.
PAGE 10
MAX1640/MAX1641 Adjustable-Output, Switch-Mode Current Source with Synchronous Rectifier DC IN PDRV I/0 D0 I/0 D1 P MAX1640 NDRV N LOW-SIDE IS SHORTED PGND CS+ RSENSE CH0 CSCH1 R3 T TERM BATT GND R4 Figure 4. Microcontroller Battery Charger Rectifier Diode If an N-channel MOSFET synchronous rectifier is not used, a Schottky rectifier is needed. The MAX1640/ MAX1641’s high switching frequency demands a highspeed rectifier (Table 2). Schottky diodes such as the 1N5817–1N5822 are recommended.
PAGE 11
MAX1640/MAX1641 Adjustable-Output, Switch-Mode Current Source with Synchronous Rectifier Layout and Grounding Due to high current levels and fast switching waveforms, proper PC board layout is essential. High-current ground paths should be connected in a star configuration to PGND. These traces should be wide to reduce resistance and as short as possible to reduce stray inductance. All low-current ground paths should be connected to GND. Place the input bypass capacitor as close as possible to IN.
PAGE 12
MAX1640/MAX1641 Adjustable-Output, Switch-Mode Current Source with Synchronous Rectifier _____________________________________________________________Revision History REVISION NUMBER REVISION DATE 2 5/09 DESCRIPTION Added lead-free package to Ordering Information, corrected R3 equation, updated Pin Description and figure references PAGES CHANGED 1–8, 10, 11 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product.