IL33193
Vbat
Vbat
«On» «Off»
«On»«Off»
t1
tn
Fn=1/tn
TIME
tf
Ft=1/tf
TIME
Figure 1 - Normal Operation Oscillator
Timing Diagram
Figure 2 - One Defective Lamp Oscillator
Timing Diagram
INTRODUCTION
The IL33193 is designed to drive the direction indicator flasher relay. It is a new generation industry standard
UAA1041 “Flasher”. It consists of the following functions:
• Supply and Protections
• On–Chip Relay Driver
• Oscillator
• Starter Functions
• Lamp Fault Detector with Internal RF Filter
• Standby Mode
Supply and Protection Systems
Pin 1 is connected to ground via resistor R3 which limits he 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 34 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 1). 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 2), the flashing frequency changes to: Fn = 2.2*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 The fault detection delay is from the time relay R1 is on and fault detection is enabled.
Where a 21 W lamp opens, the delay is expressed as: t2 = K2*R1*C1
3
INTEGRAL [ INTEGRAL CORP. ]
