R5421N111C Datasheet, PDF (1/19 Pages) RICOH electronics devices division – Li-lon BATTERY PROTECTOR

’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 VDET1, the output of COUT
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 COUT becomes high when the VDD voltage is coming down to a level lower than “VREL1”, or
when a kind of loading is connected to VDD after a charger is disconnected from the battery pack while the VDD level is in
between “VDET1” and “VREL1” in the R5421NxxxC/F version.
The output of DOUT 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 VDET2.
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 DOUT 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 DOUT 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 DOUT being enabled to low level. Once after detecting excess current, the VD3 is released and DOUT level
switches to high by detaching a battery pack from a load system.
Further, short circuit protector makes DOUT level to low immediately with external short circuit current and removing external
short circuit leads DOUT 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 COUT and DOUT are CMOS. 6-pin, SOT23-6 is available.
s 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

Variety of detector threshold .....................................Over-charge detector threshold
±2.5%
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

Output delay of over-charge ......................................Time delay at C3=0.01µF and VDD=4.3V
±15%

Output delay of over-discharge .................................VDD=2.4V with built-in capacitor
75ms for R5421N111C

Small package............................................................SOT-23-6 / 6-pin
10ms for R5421N111C/112C
s 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-