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U643

ATMEL Corporation
Part Number U643
Manufacturer ATMEL Corporation
Description Flasher/ 30-mohm Shunt
Published Apr 16, 2005
Detailed Description U643B Flasher, 30-mW Shunt Description The bipolar integrated circuit U643B is used in relaycontrolled automotive flashe...
Datasheet PDF File U643 PDF File

U643
U643

Overview
U643B Flasher, 30-mW Shunt Description The bipolar integrated circuit U643B 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.
Features D Temperature and supply voltage compensated flashing frequency D Frequency doubling indicates lamp outage D Relay driver output with high current carrying capacity and low saturation voltage D Minimum lamp load for flasher operation: ≥ 1 W D Very low susceptibility to EMI D Protection according to ISO/TR 7637/1 level 4 Block Diagram + VS + 49 6 C1 4 Measuring comparator K 1 V6–81 mV 20 kW K1 2 R3 Shunt 5 kW 7 30 mW K2 R1 Pulse generator 3 49 a–Comparator K2 20 kW 49 a–Comparator K3 K3 23 V 20 kW 5 kW IC Ground 1 95 9756 Relay 8 R2 49 a 1.
5.
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.
2.
2 kW 5 R4 470 W 5 W 21 W 21 W 21 W 21 W 5 W Indicator lamps GND – 31 Figure 1.
Application circuit as a car flasher, Resistor R1 and R2: 1/4 Watt R4 for protection against continuous reversed polarity: 0.
5 Watt Ordering Information Extended Type Number U643B U643B-FP Package DIP8 SO8 Remarks Rev.
A3, 10-Apr-01 1 (5) U643B Pin Description Pin 1 2 3 4 5 6 7 8 Symbol GND VS REL OSC OSC VS LD SI IC ground Supply voltage VS Relay driver C1 Oscillator R1 Oscillator Supply voltage VS Lamp failure detection Start input (49a) Figure 2.
Pinning OSC REL 3 4 VS 2 7 LD Function GND 1 8 SI U643B 6 Vs 5 OSC 94 9290 Functional Description Pin 1, GND The integrated circuit is protected against damage via resistor R4 to ground (–31) in the case of battery reversal.
An integrated protection circuit together with external resistances R2 and R4 limits the current pulses in the IC.
Pin 2, Supply voltage, VS - Power The arrangement of the supply connections to Pin 2 must be so as to ensure that, on the connection printed circuit board (PCB), the resistance of VS to Pin 6 is lower than that to Pin 2.
Pin 3, Relay control output (driver) The relay control output is a high-sid...


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