MAX1640, MAX1641 Adjustable-Output, Switch-Mode Current Sources with Synchronous Rectifier

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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 harmonics 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-modulation (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.

Key Features

Applications/Uses

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)

	Backup Battery Charger
	Battery-Powered Applications
	Cell Phones
	Cordless Phones
	Handy Terminals
	Laptop, Notebook, and Palmtop Computers
	PCS Phones
	Portable Consumer Products

Key Specifications: Battery Chargers

Part Number

Cell Chemistry

Number of NiMH or NiCd cells

Number of Lithium-Ion cells

Protected V_IN (max) (V)

Charging V_IN (max) (V)

Internal FET/Transistor

Charger (V)

Charge Rate Set by

Charge Termination

Charge Regulation

EV-Kit

Package

Smallest Available Package (max w/pins) (mm²)

RoHS Available

Operating Temp. Range (°C)

Price^**

MAX1640

Li-Ion
Li-Polymer
NiCd
NiMH

10
11
12
13
14
15
16
2
3
4
5
6
7
8
9

1
2
3
4
5
6

2 to 24

Resistor

External Control

Switchmode

Yes

DICE SALES/0
QSOP/16

Yes

-40 to +85

$2.75 @ 1k

MAX1641

$2.75 @ 1k

See All Battery Chargers (60)

Notes:
^**This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific prices and delivery, please see the price and availability page or contact an authorized distributor.