SM6781BV Datasheet, PDF (8/10 Pages) Nippon Precision Circuits Inc – Ni-MH/Ni-Cd Battery Charger IC

SM6781BV
BATT Input
The voltage applied to the BATT input, used for battery voltage detection, is a voltage potential, derived by a
voltage divider resistor network (100kΩ or higher recommended) or other means, that represents the voltage of
a single battery cell during charging. If a single cell only is under charge, a current limiting resistor (100kΩ or
higher is recommended) should be connected between the battery and BATT input.
Current
Source
Current
Source
Ra
N
BATT pin
Rb
Ra
Rb
=N−1
N:Number of cells
100kΩ
BATT pin
Figure 5. BATT connection example (multiple)
Operating Mode vs. BATT Input Voltage
Figure 6. BATT connection example (single)
Battery voltage
[V]
VDD − 0.5
Battery
check
Quick
charge
VDD − 1.5
−∆V Standby
detect mode
Valid
NG
2.0
Valid ^Valid
1.0
0.6
NG
0
Charging Operating Status
Charging status
Quick charge
Quick charge hold
Quick charge inhibit
Quick charge finish
Standby
Conditions
INH
Battery
check OK
LOW
Yes
LOW
No
HIGH
–
LOW
Yes
–
–
CHGN output
High impedance
LOW
LOW
LOW
High impedance
LEDN output
LOW (ON)
1Hz (pulsing)
1Hz (pulsing)
High impedance (OFF)
High impedance (OFF)
Internal timer
Count
Hold
Hold
Reset
Reset
NIPPON PRECISION CIRCUITS—8