Maker : ATMEL Corporation
Part No. : U2043B

  Datasheet PDF : U2043B.pdf
  Cross Reference : U2043B Cross Reference
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Shortcut : U2043B  U2043B  U2043B-FP 

Product Information

Features Temperature and Voltage Compensated Frequency Warning Indication of Lamp Failure by Means of Frequency Doubling Minimum Lamp Load for Flasher Operation ≥ 10W Relay Output with High Current Carrying Capacity and Low Saturation Voltage • Low Susceptibility to EMI • • • • www.DataSheet4U.com 1. Description The integrated circuit U2043B is used in relay-controlled automotive flashers where a high EMC level is required. A lamp outage is indicated by frequency doubling during hazard mode as well as direction mode. The pilot lamp can be connected either to VBatt or GND. Figure 1-1. Block Diagram +VS + 49 6 C1 Measuring comparator 4 K 1 V 6-81 mV 7 Pilot lamp Pulse generator 3.8 k Ω 8 K 3 V 6-5 V 49 a-Comparator 23 V 1 IC Ground R1 100 Ω GND - 31 5 W 21 W 21 W 21 W Indicator lamps Pilot lamps 21 W 5 W 3 Relay R2 3.3 k Ω 49 a 5W 2 R3 Shunt 30 m Ω Flasher, 30 mΩ Shunt, Pilot Lamp to GND or VBatt U2043B R1 5 Rev. 4720B–AUTO–09/05 2. Pin Configuration Figure 2-1. Pinning DIP8/SO8 GND 1 2 8 7 SI VS REL www.DataSheet4U.com LD VS OSC U2043B 3 4 6 5 OSC Table 2-1. Pin 1 2 3 4 5 6 7 8 Pin Description Symbol GND VS REL OSC OSC VS LD SI Function IC ground Supply voltage VS Relay driver C1 Oscillator R1 Oscillator Supply voltage VS Lamp failure detection Start input (49a) 2 U2043B 4720B–AUTO–09/05 U2043B 3. Functional Description 3.1 GND (Pin 1) 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. 3.2 Supply Voltage, VS Power (Pin 2) 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. www.DataSheet4U.com 3.3 Relay Control Output (Driver, Pin 3) The relay control output is a high-side driver with a low saturation voltage and capable of driving a typical automotive relay with a minimum coil resistance of 60Ω. 3.4 Oscillator (Pin 4 and 5) Flashing frequency, f1, is determined by the R1C1 components as follows (see Figure 1-1 on page 1): 1 f 1 = ------------------------------------ Hz R 1 × C 1 × 1.5 where C1 ≤ 47 µF R1 = 6.8 kΩ to 510 kΩ In the case of a lamp outage (see pin 7) the oscillator frequency is switched to the lamp outage frequency f2 with f2 ≈ 2.2 × f1. Duty cycle in normal flashing mode: Duty cycle in lamp outage mode: 50% 40% (bright phase) 3.5 Supply Voltage, Sense (Pin 6) For accurate monitoring via the shunt resistor, a minimized layer resistance from point VS/shunt to pin 6 is recommended. 3 4720B–AUTO–09/05 3.6 Lamp Outage Detection (Pin 7) The lamp current is monitored via an external shunt resistor R3 and an internal comparator K1 with its reference voltage of typically 81 mV (VS = 12V). The outage of one lamp out of two lamps is detected according to the following calculation: Nominal current of 1 lamp: Nominal current of 2 lamps: 21W/(VS = 12V): 2 × 21W/(VS = 12V): Ilamp = 1.75A Ilamp = 3.5A We recommend setting the detection threshold in the middle of the current range: Ioutage ≈ 2.7A Thus, the shunt resistor is calculated as: www.DataSheet4U.com R3 = VT (K1)/Ioutage R3 = 81 mV/2.7 A = 30 mΩ Comparator K1’s reference voltage is matched to the characteristics of filament lamps (see section “Control Signal Threshold”). The combination of the shunt resistor and the resistance of the wire harness prevents pin 7 from a too high voltage in the case of shorted lamps. 3.7 Start Input (Pin 8) Start condition for flashing: The voltage at pin 8 has to be less than VS – 5V (flasher switch closed). Humidity and dirt may decrease the resistance between 49a and GND. If this leakage resistance is > 5 kΩ the IC is still kept in its off-condition. In this case the voltage at pin 8 is greater than VS – 5V. During the bright ph...

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