The MAX1640/MAX1641 is a CMOS switch-mode current source with an adjustable output voltage range of 2V to 24V and a maximum duty cycle of 100%. It operates from a +5.5V to +26V input voltage and is ideal for microprocessor-controlled battery chargers.
The MAX1640 and MAX1641 are CMOS adjustable‑output, switch‑mode current sources with a synchronous rectifier. They operate from a 5.5 V to 26 V input and support output voltages from 2 V to 24 V, making them suitable for microprocessor‑controlled battery chargers and portable devices. Current and voltage settings are programmed with external resistors, while an optional external N‑channel MOSFET can be used for synchronous rectification to improve efficiency (up to 95%).
The datasheet provides absolute maximum ratings, electrical characteristics, pin descriptions, typical operating curves, and recommended application circuits. It also covers programming methods for off‑time, output‑voltage termination, and various charging modes such as fast‑charge, top‑off, pulse‑trickle, and off‑mode. Layout and grounding guidelines are included to ensure reliable high‑frequency operation.
| Input Voltage Range | 5.5 V to 26 V |
|---|---|
| Efficiency | up to 95 % |
| Maximum Duty Cycle | 100 % |
| Package | 16‑Pin QSOP |
The devices operate with an input voltage from 5.5 V up to 26 V.
The output voltage is programmed via the SET pin using a resistor divider that sets VSET; the relationship is given by Ri = Re (VREF/ VSET – 1) with 10 kΩ < R2 < 300 kΩ.
Typical efficiency reaches about 95 % under normal operating conditions.