BM3451 Series
3/4/5 Cell Battery Protectors
BYD Microelectronics Co., Ltd.
General Description
The BM3451 is a professional protection IC for 3/4/5 cells rechargeable battery pack; it is highly
integrated, and generally used in power tools, electric bicycles and UPS applications.
The BM3451 works constantly to monitor each cell’s voltage, the current of charge or discharge, and
the temperature of the environment to provide overcharge, over-discharge, discharge overcurrent, short
circuit, charge overcurrent and over-temperature protections, etc. Besides, it also can change the
protection delay time of overcharge, over-discharge and discharge overcurrent by setting the external
capacitors.
The BM3451 provides external bleeding for cell-capacity balance function to avoid unbalanced
capacity between each cell. Thus, the batteries can work for longer.
Extended function module embedded in the BM3451 ICs can make them work for more battery packs
with multiple chips, and they can protect 6-cell batteries or more than 6-cell batteries.
Features
(1) High-accuracy voltage detection for each cell
·overcharge threshold
3.6V~4.6V
accuracy: ±25 mV (+25℃)
accuracy: ±40 mV (-40℃ to +85℃)
accuracy: ±50 mV
·overcharge hysteresis
·over-discharge threshold
·over-discharge hysteresis
0.1V
1.6V~3.0V
accuracy: ±80 mV
0V / 0.2V / 0.4V accuracy: ±100 mV
(2) Three grades voltage detection of discharge overcurrent
·discharge overcurrent 1
·discharge overcurrent 2
·short circuit
0.025 V ~ 0.30 V
(50 mV step)
0.2 V / 0.3V / 0.4V / 0.6 V
0.8V / 1.2 V
(3) Charge overcurrent detection
·detection voltage
-0.03V / -0.05V / -0.1V / -0.15V / -0.2 V
(4) 3/4/5 cell protection enable
(5) Setting of output delay time
·overcharge, over-discharge, discharge overcurrent 1 and discharge overcurrent 2 protection delay
time can be set by external capacitors
(6) Supports external bleeding for balance
(7) Controlling the state of charge or discharge by external signals
(8) The maximum output voltage of CO / DO: 12V
(9) Over-temperature protection
(10) Breaking wire protection
(11) Low power consumption
·operation mode(with Temp protection)
·operation mode(without Temp protection)
·sleeping mode
25 μA typical
15 μA typical
6 μA typical
Datasheet
WI-D06-J-0036 Rev.A/1
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