High-Accuracy 12-/16-Cell Measurement AFEs

The MAX14920/MAX14921 battery measurement analog front-end devices accurately sample cell voltages and provide level shifting for primary/secondary battery packs up to 16 cells/+65V (max). The MAX14920 monitors up to 12 cells, while the MAX14921 monitors up to 16 cells. Both devices simultaneously sample all cell voltages, allowing accurate state-of-charge and source-resistance determination. All cell voltages are level shifted to ground reference with unity gain, simplifying external ADC data conversion.

The devices have a low-noise, low-offset amplifier that buffers differential voltages of up to +5V, allowing monitoring of all common lithium-ion (Li+) cell technologies. The resulting cell voltage error is ±0.5mV.

The devices’ high accuracy make them ideal for monitoring cell chemistries with very flat discharge curves, such as lithium-metal phosphate.

Passive-cell balancing is supported by external FET drivers. Integrated diagnostics in the devices allow open-wire detection and undervoltage/overvoltage alarms. The devices are controlled by a daisy-chainable SPI interface.

The MAX14920 is available in a 64-pin (10mm x 10mm) TQFP package with an exposed pad. The MAX14921 is available in an 80-pin (12mm x 12mm) TQFP package. Both devices are specified over the -40°C to +85°C extended temperature range.

Applications

* e-Transportation Energy Packs * Energy Storage Packs * Industrial Battery Backup Systems * Telecom Battery Backup Systems

* High Accuracy

* ±0.5mV (max) Cell Voltage Error

* Simultaneous Cell Voltage Sampling

* Self-Calibration

* Integrated Diagnostics

* Open-Wire and Short Fault Detection

* Undervoltage/Overvoltage Warning

* Thermal Shutdown

* High Flexibility

* SPI Interface

* 12-Cell and 16-Cell Versions

* +6V Minimum (3 Cells) Operation

* +0.5V to +4.5V Cell Voltage Range

* Integrated Cell-Balancing FET Drivers

* Integrated 5V LDO

* Low Power

* 1µA Shutdown Mode

* 1µA/10µA Cell Current Draw