MAX846AEEE

The MAX846AEEE is one member of the MAX846A series.It has the following features including (1)multichemistry charger system (Li-Ion, NiMH, NiCd),(2)independent voltage and current loops,(3)space-saving 16-pin QSOP,(4)charging-current-monitor output.

The MAX846A is a cost-saving multichemistry batterycharger system that comes in a space-saving 16-pin QSOP. This integrated system allows different battery chemistries (Li-Ion, NiMH or NiCd cells) to be charged using one circuit.In its simplest application, the MAX846A is a standalone,current-limited float voltage source that charges Li-Ion cells. It can also be paired up with a low-cost microcontroller (C) to build a universal charger capable of charging Li-Ion, NiMH, and NiCd cells.The MAX846A has a built-in 1%, 3.3V, 20mA linear regulator capable of powering the C and providing a reference for the C's analog-to-digital converters. An on-board reset notifies the controller upon any unexpected loss of power. The C can be inexpensive, since its only functions are to monitor the voltage and current and to change the charging algorithms.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.

Note that the C only needs to configure the system for correct voltage and current levels for the battery being charged, and for Ni-based batteries to detect end-ofcharge and adjust the current level to trickle. The controller is not burdened with the regulation task.Float-voltage accuracy is important for battery life and for reaching full capacity for Li-Ion batteries. Component selection is similar to that of stand-alone operation. By using DACs or C PWM outputs, the float voltage and charging current can be adjusted by the C. When a Ni-based battery is being charged, disable the float-voltage regulation using the OFFV input. The C can also monitor the charge current through the battery by reading the ISET output's voltage using its ADC. Similarly, the battery voltage can be measured using a voltage divider from the battery.