Other Parts Discussed in Thread: OPA4197
Tool/software:
Hi,
I’m seeking advice on selecting the appropriate battery monitoring IC for a project involving a 4S LiFePO4 battery pack. My key requirements are:
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Accurate Cell Voltage Monitoring: I need to measure individual cell voltages in a series-connected pack.
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Open-Wire Detection: The system should reliably detect when a cell is physically disconnected (i.e., reading 0V or open-circuit conditions).
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Handling Removed Cells: The IC should continue monitoring the remaining cells accurately, even if one or more cells are removed from the stack.
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External MCU Integration: I’ll interface the monitoring system with an external microcontroller via I2C or SPI.
I initially considered using precision rail-to-rail op-amps (like the OPA4197) configured as differential amplifiers to measure cell voltages. However, handling floating inputs when cells are removed has proven to be a non-trivial design challenge. To simplify the design, I’m considering dedicated battery monitoring ICs for voltage readings and open-wire detection, with the BQ76952 as a potential candidate.
That said, I’m concerned about the BQ76952’s open-wire detection capabilities. From what I understand:
- The IC doesn’t provide a dedicated register for tracking which cell is disconnected.
- It supports detecting only one open-wire event at a time.
- In the case of an open wire, the IC may trigger overvoltage protection for the cell above and undervoltage protection for the cell below. However, this indirect detection method may not satisfy my requirement to explicitly identify multiple disconnected cells while still monitoring the remaining ones accurately.
I'm unsure if I should continue with my op-amp setup or shift to a dedicated battery monitoring IC.
Would you recommend any specific TI products that can meet these requirements? Additionally, any insights on configuring the ICs to handle open-wire detection and removable cells would be greatly appreciated.
Thanks.