ICS1708 Datasheet, PDF (2/16 Pages) List of Unclassifed Manufacturers – QuickSaver Charge Control IC for Nickel-Cadmium and Nickel-Metal Hydride Batteries

ICS1708
Pin Configuration
CHG
MMN
CMN
VSS
1
8
2 _ICS1708 7
3
6
4
5
VDD
VIN
OPREF
RC
Pin Definitions
8-Pin DIP or SOIC
Pin
1
2
3
4
5
6
7
8
Note:
Name Type
Definition
CHG
OUT
Active high (PFET), active low (NFET) 25mA max. TTL compatible signal used to turn on and off an external current source to
provide pulsed current to charge the battery.
CMN
OUT
Charge mode indicator. NFET drain rated at 40mA max. turns on an external indicator to show the controller is applying either a
SoftStart charge or fast charge.
MMN
OUT
Maintenance mode indicator. NFET drain rated at 40mA max. turns on an external indicator showing the battery is ready to use as the
topping charge or maintenance charge is applied.
VSS
Ground.
RC
IN
An external resistor and capacitor sets the frequency of the internal clock.
OPREF
IN
Open circuit (no battery) voltage reference. A pull down or external resistor divider from 5V sets a voltage reference on this pin used
to detect the presence of a battery.
VIN
IN
Battery voltage normalized to one cell with an external resistor divider.
VDD
Device supply =+5.0 VDC +/- 5% regulated. The ICS1708 requires 11mA max. average that includes brief 50mA peak currents.
When used, LEDs, pull-up resistors, and drivers require additional current from the +5VDC supply. An electrolytic and ceramic
capacitor between (or very close to) both VDD and VSS is recommended for bypassing.
Pin 6 has an internal pull-up.
Input and output pins have internal ESD protection diodes to VDD and VSS for 2KV protection per MIL STD 883 method 3015.7.
Controller Operation
Charging Stages
The charging sequence consists of four stages. The application of current is shown graphically in Figure 1. The SoftStart stage gradually
increases current levels up to the user selected fast charge rate during the first two minutes. The SoftStart stage is followed by the fast
charge stage, which continues until termination. After fast charge termination, a reduced duty cycle topping charge is applied, followed by
a further reduced cycle maintenance charge. After fast charge termination, the battery is charged and ready to use.
97%
18%
A ve ra g e
C urrent
(not to scale)
Fast Charge
Topping Charge
2.5 to 20%
Maintenance Charge
0.6 to 5%
Stage 1
Stage 2
Stage 3
Stage 4
0
2 m in
term ination
term ination + Tim e (not to scale)
Figure 1: Graphical representation of average current levels during the four charging stages
2