’99.9.21
Li-Ion BATTERY PROTECTOR
R5421NxxxC/xxxF series
s
OUTLINE
The R5421NxxxC/F Series are protection ICs for over-charge/discharge of rechargeable one-cell Lithium-ion (Li+) excess load
current, further include a short circuit protector for preventing large external short circuit current.
Each of these ICs is composed of three voltage detectors, a reference unit, a delay circuit, a short circuit protector, and a logic
circuit. When charging voltage crosses the detector threshold from a low value to a value higher than V
DET1
, the output of C
OUT
pin, the output of over-charge detector/VD1, switches to low level, charger's negative pin level. After detecting over-charge the
VD1 can be reset and the output of C
OUT
becomes high when the V
DD
voltage is coming down to a level lower than “V
REL1
”, or
when a kind of loading is connected to V
DD
after a charger is disconnected from the battery pack while the V
DD
level is in
between “V
DET1
” and “V
REL1
” in the R5421NxxxC/F version.
The output of D
OUT
pin, the output of over-discharge detector/VD2, switches to low level after internally fixed delay time
passed, when discharging voltage crosses the detector threshold from a high value to a value lower than V
DET2
.
After R5421NxxxC/F Series detect the over-discharge voltage, connect a charger to the battery pack, and when the battery
supply voltage becomes higher than the over-discharge detector threshold, VD2 is released and the voltage of D
OUT
becomes
“H” level. In the case of F version, after detecting the over-discharge detection, when the battery supply voltage becomes
equal or higher than over-discharge released voltage, VD2 is also released by the condition, and the voltage of D
OUT
becomes
“H” level.
An excess load current can be sensed and cut off after internally fixed delay time passed through the built in excess current
detector, VD3, with D
OUT
being enabled to low level. Once after detecting excess current, the VD3 is released and D
OUT
level
switches to high by detaching a battery pack from a load system.
Further, short circuit protector makes D
OUT
level to low immediately with external short circuit current and removing external
short circuit leads D
OUT
level to high. After detecting over-discharge, supply current will be kept extremely low by halt some
internal circuits operation. The output delay of over-charge detectors can be set by connecting external capacitors. Output type
of C
OUT
and D
OUT
are CMOS. 6-pin, SOT23-6 is available.
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FEATURES
Low supply current....................................................Supply current
Standby current (detecting over-discharge)
Typ. 3.0µA
Typ. 0.3µA
(for R5421NxxxC)
Typ. 1.0µA
(for R5421NxxxF)
High accuracy detector threshold ..............................Over-charge detector (Topt=25°C)
±25mV
(Topt=0 to 50°C)
±30 mV
Over-discharge detector
±2.5%
Variety of detector threshold .....................................Over-charge detector threshold
4.0V - 4.4V step of 0.005V
Over-discharge detector threshold
2.0V - 3.0V step of 0.005V
Built-in protection circuit ..........................................Excess current protection
0.05V - 0.4V step of 0.005V
Accuracy
±15%
Output delay of over-charge ......................................Time delay at C3=0.01µF and V
DD
=4.3V
75ms for R5421N111C
Output delay of over-discharge .................................V
DD
=2.4V with built-in capacitor
10ms for R5421N111C/112C
Small package............................................................SOT-23-6 / 6-pin
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APPLICATIONS
Li+ one-cell protector for battery pack
High precision protectors for cell-phones and any other gadgets using on board Li+ one-cell battery
Rev.1.11
-1-
RICOH [ RICOH ELECTRONICS DEVICES DIVISION ]
