IL33193-03N Datasheet, PDF (3/6 Pages) IK Semicon Co., Ltd – Automotive Direction Indicator

Vbat
Relay on
Function Description
Vbat
IL33193-03
Relay Relay
on off
t1
tn
Relay off
Fn=1/tn
Time
Fig. 7. Normal Operation Oscillator
Timing Diagram
tf
Ft=1/tf
Time
Fig. 8. One Defective Lamp Oscillator
Timing Diagram
Supply and Protection Systems
Pin 1 is connected to ground via resistor R2 which limits the current in the event of any high voltage transients.
Pin 2 (VCC) is the positive supply and may be connected directly to the vehicle’s battery voltage.
Overvoltage and Double Battery Protection: When the applied VCC to VSS voltage is greater than 22 V, the
overvoltage detector circuit turns the relay driver off. Both the device and the lamps are protected if two 12 V batteries
are connected in series and used to jump start the vehicle.
Load Dump Overvoltage Protection: A 29 V overvoltage detector protects the circuits against high voltage transients
due to load dumps and other low energy spikes. The relay driver is automatically turned on whenever the VCC to VSS
voltage is greater than 32 V.
Overvoltage Protection, High Voltage Transients: The Enable and the Starter pins are protected against positive and
negative transients by internal on–chip diodes.
On–Chip Relay Driver
The device directly drives the flasher relay. The output structure is an Emitter of an NPN transistor. It contains the
free wheeling diode circuitry necessary to protect the device whenever the relay is switched off.
Oscillator
The device uses a sawtooth oscillator (Figure 7). The frequency is determined by the external components C1 and
R1. In the normal operating mode, the flashing frequency is: Fn = 1/R1*C1*Kn. With a defective (open) 21 W lamp
(Figure 8), the flashing frequency changes to: Fn = 2.5*Fn.
The typical first flash delay (the time between the moment when the indicator switch is closed and the first lamp flash
occurs) is: t1 = K1*R1*C1 Where a 21 W lamp opens, the delay is expressed as: t2 = K2*R1*C1
Short circuit detection delay t3 = K1*R1*C1.
Starter
Pin 8 is connected through a 2.2 kresistor to the flashing lamp. Pin 8 is the input to the Starter function and
senses the use of S1 by sensing ground through the lamp (Figure 9).
Lamp Fault Detector with Internal RF Filter
A Lamp defect is sensed by the lamp fault detector’s monitoring of the voltage developed across the external shunt
resistor R4 via the RF filter. The RS voltage drop is compared to a Vbat dependent internal reference voltage (Vref) to
validate the comparison over the full battery voltage range. A detected fault causes the oscillator to change frequency
(Figure 8).
February. 2012. rev. 01