MAX1894 データシートの表示（PDF） - Maxim Integrated
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MAX1894 Datasheet PDF : 16 Pages
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Advanced Li+ Battery-Pack Protectors
OVERDISCHARGE
PROTECTION
PACK +
RTKO
510Ω
PACK -
TRICKLE
CHARGE
RSENSE
0.02Ω
R5
10Ω
OVERCHARGE
PROTECTION
D1
CMPSH-3
15
DSO
14
CGO
13
TKO
2 VCC
R4
C6
51Ω 0.1µF
1
B4P
C4
R3
1kΩ
1µF
3
B3P
R2
C3
0.1µF
4 IC3
1kΩ
5 B2P
C2
0.1µF
6 IC2
R1
1kΩ
7 B1P
C1
0.1µF
8 IC1
9 BN
16
SRC
C5
2.2µF
BN
MAX1894X
MAX1924X
SHDN 12
CTL 11
MICRO-
CONTROLLER
PKN
10
Figure 1. Typical Applications Circuit with Trickle Charge
the direction of current flow. To reverse the current flow,
the charger has to be removed (Figure 5). The sustain-
ing condition for the latch is a 100mV (max) voltage
drop across SRC and B4P. Since the charge-current
fault threshold between BN and PKN is also 100mV
(typ), the RDS_ON of the overcharge protection MOSFET
must be greater than the sense resistor in order to
ensure a latched state.
Discharge-Current Fault Protection
The MAX1894/MAX1924 protect against excessive dis-
charge-current by monitoring the voltage developed
across RSENSE. If VRSENSE exceeds the discharge-cur-
rent fault threshold (VOD_TH, typically 145mV) for more
than 3ms, the discharge-current comparator is tripped,
setting DSO, CGO, and TKO high.
Discharge-current fault is latched and is not reset until
the MAX1894/MAX1924 detect a reversal in the direc-
tion of current flow. To reverse the current flow, a
charger must be applied (Figure 6).
Pack-Short Current Fault Protection
The MAX1894/MAX1924 protect against a shorted
pack by monitoring the voltage developed across
RSENSE. If VRSENSE exceeds the pack-short threshold
(VPS_TH, typically 405mV) for more than 450µs, the
pack-short comparator is tripped, setting CGO, DSO,
and TKO high.
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