User Guide

NHB–3
Technical Documentation
PAMS
Cigarette Lighter Charger LCH–2
Original 26/97 Page 5
Phone operating status LED Display
Cigarette lighter charger connected
to vechile, phone disconnected green
Phone connected to charger, charging
disabled due to battery temperature green state A
Rapid charge red state A
Battery full –> trickle charge green state B
Calling state green/ state A
red
*)
*) Battery capacity is maintained during a phone call by occasional rapid charge
cycles. Consequently, the LED can be indicating either red or green.
Electrical Specifications
Operating input voltage: 9 to 32 V d.c.
Input current without phone: < 60 mA
Max. input current: 1.8 A
Output voltage:
• constant voltage 12.5 ±1 V/0...400 mA
• constant current 800 ±70 mA/5.0...10 V
Functional Description
General
The charger module consists of a switched–mode converter and a bicolour indi-
cator LED. The converter is of the step up/down type, i.e. the output voltage
can be lower or higher than the input voltage.
Converter
Converter input current is received via filter capacitor C101. The converter con-
sists of coils L110, L112, FET switch V112, d.c. level shifting capacitor C111
and Schottky diode V113. Output energy is stored and filtered by C112, L111
and C113.
In series with converter coil L112 is resistor R116, used for measuring the out-
put current. When operating, the converter generates a negative voltage drop
(as compared to ground level) at R116, directly proportional to output current.
Converter control is by N110, a quad comparator with open–collector output.
The 5 V reference supply is generated by regulator N100.