參數(shù)資料
型號(hào): MM1248
廠商: MITSUMI ELECTRIC
英文描述: Control of Lithium Ion Battery Charging and Discharging
中文描述: 控制的鋰離子電池充放電
文件頁(yè)數(shù): 5/8頁(yè)
文件大?。?/td> 210K
代理商: MM1248
MITSUMI
Control of Lithium Ion Battery Charging and Discharging MM1248
Circuit conventions
Charge control unit
Overcharge detection unit
Subtraction amp, buffer amp, voltage comparator, dead time setting circuit
Discharge control unit
Cell voltage monitoring circuit, dead time setting circuit
Overvoltage sensing (rough detection) unit
High-precision reference voltage unit
Operating outline
1. Charge control
Charge control is turned on and off using the CON pin; when CON is low the charge control unit is in
operation. The error amp of the charge control unit takes inputs of 4.155V from the high-precision reference
voltage unit and the battery module voltage monitor output. The battery module voltage monitor outputs a
voltage equal to 1/3 the battery module voltage, so that in charging control the charging control FET (pin 2)
is controlled such that the battery module voltage is 4.155 3 V.
This block performs constant-voltage control only; current limiting (constant-current control) should be
implemented on the charging input side.
2. Overcharge detection
There are two blocks for overcharge detection; three output modes are provided according to input
conditions and cell voltage.
1. Charging signal on (during discharge)
2. Charging signal off (during discharge)
3. Discharge off
2-1. Charging signal on
The high-precision overcharge sensing unit is always in the operating state, and the voltage of each cell is
monitored.
In order to monitor each cell's voltage precisely, subtraction amps are provided for monitoring M and H cell
voltages, and a buffer amp is used to monitor the L cell voltage. By means of these amps the voltage of
each cell is converted to a GND-reference voltage, and compared with the high-precision reference voltage
of 4.335V.
If the voltage of any one of the cells exceeds 4.335V, the overvoltage is sensed, and the dead time setting
pin (CCC pin 7) is charged by a constant current; when the CCC pin is charged to the threshold voltage of
the dead time setting circuit (4.35V), an overvoltage signal is output.
(OV1 pin "H", OV2 pin "L")
When an overcharge signal is output, the overvoltage monitoring unit switches from the overvoltage state
to the reset monitoring state, and an overcharge signal is output until the voltages of all cells fall to 4.16 V.
To summarize the sequence of operations, when the voltage of any of the cells remains in the overcharge
state continuously for the specified time (the dead time), that cell is judged to be in an overcharged state
and is switched to overvoltage output; when all the cell voltages drop to the overcharge reset voltage or
below, the overcharge state is canceled.
On entering the overcharge state, if the charge control unit circuit is turned off, the latter unit will not
operate.
Pin
Output logic
Output type
Normal
Overvoltage
OV1
L
H
PNP output, internal pull-down resistance
OV2
High impedance
L
NPN open-collector output
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