U2403B

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 (V1 > VS), 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 R1 Power supply AC/DC LED2 Battery inserted Charge R5 LED 8 Charge mode indicator LED1 Ready VS 6 Power supply VS = 3.5 to 12 V GND 7 Test mode 5 STM 94 8629 C1 í max 140°C 1 V1 Timer and control logic VRef = 1.5 V/ 0.1 V/ 0 V VRef í 2 Shunt + – 3 Sense R3 R4 RC oscillator 4 Osc C4 Figure 1. Block diagram with...