MAX1737EEI+

The MAX1737EEI+ is a versatile switch-mode lithium-ion battery charger controller from Analog Devices, capable of charging one to four cells. It provides a regulated charging current and voltage with an impressive ±0.8% total voltage error at the battery terminals. The device features an external N-channel switch and synchronous rectifier for high efficiency across a wide input voltage range, up to +28V.

A built-in safety timer automatically terminates charging once an adjustable time limit is reached, preventing overcharging. An additional control loop monitors the total input current to prevent overload of the input supply, making it suitable for low-cost wall adapters. The per-cell battery voltage regulation limit can be set between +4.0V and +4.4V and configured for one to four cells via pin strapping. Battery temperature is monitored using an external thermistor to ensure charging only occurs within an acceptable temperature range.

This IC is available in a space-saving 28-pin QSOP package, making it ideal for applications such as notebook computers, hand-held instruments, Li+ battery packs, and desktop cradle chargers. The MAX1737EEI+ also boasts features like precharging for near-dead cells, continuous voltage and temperature monitoring, and low shutdown battery current (<1µA).

Key electrical characteristics include 90% conversion efficiency, a 300kHz PWM oscillator to reduce noise, and a low dropout design with 98% duty cycle. The device is specified for operation over a temperature range of -40°C to +85°C.