U2403B
Charge Timer
Description
The U2403B is a monolithic, integrated-bipolar circuit
which can be used in applications for time-controlled,
constant-current charge. Selection of charge current
versus timing is carried out by using the external circuit
at Pins 2, 3 and 4. For high current requirement, an
external transistor is recommended in series with the
battery. To protect the IC against high power loss
(typically > 140°C), the oscillator is shut down when the
reference voltage is switched off (0 V). The latter also
takes place when there is a saturation caused by collector
voltage at Pin 1. When the overtemperature has
disappeared and the collector voltage at Pin 1 has
exceeded the supply voltage (V
1
> V
S
), charge time
operation continues (see flow chart in figure 3).
Features
D
D
D
D
D
D
D
D
Easy-to-run autonomous dual rate charger
Constant charge current
3 h – 24 h charge time programmable
Low cost dc regulator
Overtemperature protection
Charge-mode indication
Operation starts at the moment of battery insertion
Fast charge time-test mode
Applications
D
Cordless telephones
D
Low-cost battery-charge timer
D
Entertainment
Package:
DIP8, SO8
Block Diagram
R
1
Power
supply
AC/DC
LED
2
Battery
inserted
Charge
R
5
LED
8
Charge mode
indicator
LED
1
Ready
V
S
6
Power supply
V
S
= 3.5 to 12 V
GND
7
Test
mode
5
S
TM
94 8629
C
1
í
max
140°C
1
V
1
Timer and control logic
V
Ref
= 1.5 V/ 0.1 V/ 0 V
V
Ref
í
2
Shunt
+
–
3
Sense
R
3
R
4
RC
oscillator
4
Osc
C
4
Figure 1. Block diagram with external circuit
TELEFUNKEN Semiconductors
Rev. A2, 14–Nov–96
1 (12)
TEMIC [ TEMIC SEMICONDUCTORS ]
