MP2797 Battery Monitor with Coulomb Counting
In a battery management system (BMS), accurately estimating the internal state of the battery pack poses one of the biggest challenges. Implementing a solution that can accurately monitor the battery’s state is critical to improving the device performance as well as user experience.
The MP279x family of battery monitors are designed as a complete analog front-end (AFE) monitoring and protection solution on lithium-ion battery strings up to 16 series cells. The MP279x family provides the following features:
- ±5mV cell measurement accuracy (25°C)
- Synchronized current and cell voltage measurements
- High-side N-channel MOSFET drivers for charge and discharge control
- Extensive, configurable hardware protections
- Coulomb counting
- Passive balancing
The Monolithic Power Systems MP2797 is a robust battery management device that provides a complete analog front-end (AFE) monitoring and protection solution. It is designed for multiple-cell series battery management systems (BMS). The device can support digital interface or SPI communication. It supports connections for 7-cell to 16-cell series battery packs, with an absolute voltage exceeding 80V on particular pins.
The MP2797 integrates two separate analog-to-digital converters (ADCs). The first ADC measures each channel’s differential cell voltages (up to 16 channels), die temperature, and 4-channel temperatures via external NTC thermistors. The second ADC measures the charge/discharge current via an external current-sense resistor. The dual ADC architecture enables synchronous voltage and current measurements for cell and pack impedance monitoring.
When paired with an MPF4279x fuel gauge, the MP2797 can achieve a state-of-charge (SOC) error to within 2%. The MP2797 includes high-side MOSFET (HS-FET) drivers for charge and discharge control. The discharge (DSG) MOSFET driver includes a configurable soft start (SS) that provides a controlled turn-on, eliminating the need for an external pre-charge circuit. The MOSFET drivers also incorporate over-current protection (OCP), short-circuit protection (SCP), battery under-voltage protection (UVP), battery over-voltage protection (OVP), and high-temperature/low-temperature protection. All of these protections have configurable thresholds.
Internal passive balancing MOSFETs can be used to equalize mismatched cells, supporting up to 58mA. There is also the option to drive external balancing transistors (MOSFET or BJT).
MP2797 Features
| MP2797 Block Diagram
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Evaluation Kit for the MP2797
The EVKT-MP2797 evaluation kits include an MP2797 evaluation board, a USB communication adaptor, and a PC-based graphical user interface (GUI) for evaluating the MP2797. The EVKT-MP2797-0000 is designed for I2C communication, and includes a USB to I2C adapter. The EVKT-MP2797-002 is designed for SPI communication, and includes a USB to SPI adapter.
| Key Features
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