U644B-FP

U644B Flasher, 18-mW Shunt, Extremly Low Current Consumption Description The bipolar integrated circuit, U644B, is used in relaycontrolled automotive flashers where a high level EMC is required. Lamp outage is indicated by frequency doubling during hazard warning as well as direction mode. If the flasher module provides an 4-pin connector the control pin of U644B (Pin 6) can be used to operate the IC in an extremly low-current mode. Features D Frequency doubling indicates lamp outage D Frequency independent of temperature and voltage change D Minimum lamp load for flasher operation: D Very low susceptibility to EMI 1 W D Relay driver output with high current-carrying capacity and low saturation voltage D Protection according to ISO TR7637/1 level 4 D Control input (Kl 15) Ordering Information Extended Type Number U644B U644B-FP Package DIP8 SO8 Remarks Block Diagram R5 10 kW 30 2 Measuring comparator K 1 V S – 49 mV 4 K1 6 15 C1 R4 Shunt 20 kW 20 kW 7 2 kW 3 18 mW K2 R1 Pulse generator 49 a Comparator K 2 20 kW 8 Relay R3 3.3 kW 30 V 1 GND R2 220 W GND –31 49 a 5 K3 49 a Comparator K 3 20 kW 13 kW 12707 Figure 1. Application circuit as a car flasher with control input Resistor R1, R2 and R3: 1/4 Watt R2 for protection against continuous reversed polarity: 1 Watt TELEFUNKEN Semiconductors Rev. A2, 25-Feb-97 1 (6) U644B +V S +49 2 Measuring comparator K 1 V S – 49 mV 4 K1 6 C1 R4 Shunt 20 kW 20 k 7 2 kW 3 18 mW K2 R1 Pulse generator 49 a Comparator K 2...