The BYD BM3451 Series datasheet details specifications and protection features for 3/4/5‑cell rechargeable battery packs.
The BM3451 is a highly integrated protection IC for 3‑, 4‑, and 5‑cell rechargeable battery packs. It continuously monitors cell voltage, charge/discharge current, and temperature to provide over‑charge, over‑discharge, discharge over‑current, short‑circuit, charge over‑current, and over‑temperature protections. Delay times for over‑charge, over‑discharge and discharge over‑current can be set with external capacitors, and an external bleeding function balances cell capacity.
Typical applications include power tools, electric bicycles and UPS backup batteries. The device supports extended‑chip configurations for protecting six‑cell or larger packs, and offers pin‑compatible packages (TSSOP28, TSSOP20) with dedicated pins for balance control, temperature sensing, and MOSFET drive signals.
| Over‑charge protection threshold | 3.6 V ~ 4.6 V |
|---|---|
| Over‑discharge protection threshold | 1.6 V ~ 3.0 V |
| Discharge over‑current 1 detection voltage | 0.025 V ~ 0.30 V |
| Maximum output voltage (CO/DO) | 12 V |
| Operating consumption (with temperature protection) | 25 µA typical |
| Sleeping consumption | 10 µA typical |
Both the CO and DO pins can output up to 12 V.
The IC is intended for power tools, electric bicycles and UPS backup battery packs.