IL33193
Starter
Pin 8 is connected through a 3.3 kW 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 (Figures 9 and 10).
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 RS 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 2).
Standby Mode
When the ignition key and warning switches are open; Enable is in a low state and the internal switches, SW1 and
SW2, are open and no current passes through the circuit. In this condition, the device’s current consumption is zero
(ICC = 0). When ignition key and warning switches are closed; Enable is in a high state with SW1 and SW2 being
closed and the circuit is powered on.
Main differences between UAA1041B & IL33193
The IL33193 is pin compatible with the UAA1041.
Supply Current
Supply current is more stable on the IL33193 when the device is in “on” or “off” state. In “on” state the supply current
is only 40% higher than when in the “off” state, as compared to a ratio of 3 times for the UAA1041. This results in a
lowern voltage drop across the ground resistor R3 (see On–Chip Relay Driver).
Short Circuit Detection
The IL33193 has no short circuit detection.
Standby Mode (Pin 6)
The UAA1041 has no standby mode. Pin 6 is used as an Enable/Disable for the short circuit detection. The IL33193
uses Pin 6 to set the device in standby mode. If Pin 6 is connected to ground, the IL33193 is in the standby mode. In
this mode, standby current is very low and Pin 8’s starter resistor R2 and a 2.0 kW internal resistor are switched off. As
soon as Pin 6 is at a high level (typical threshold = 2Vbe) the device becomes active. In the application, the IL33193
can be connected directly to the battery and awakened whenever Pin 6 is connected to the vehicle’s battery by way of a
protection resistor and the ignition key switch.
Lamp Defect Detection (Pin 7)
The UAA1041 operates with a 30 mW shunt resistor to sense the lamp current. It’s lamp defect detection threshold of
Pin 7 is typically 85 mV. The IL33193 is designed to operate with 20 mW shunt resistor and at a reduced threshold of
50 mV. This reduces power generation in the flasher module. In addition, the IL33193 incorporates an RF filter to
enhance RFI immunity.
Load Dump and Overvoltage Behavior
The UAA1041 and IL33193 both behave the same in this regard. Both have double battery detection and lamp turn–off
protection in the event of a jump start. During load dump, both devices are protected by an internal 30 V zener diode
with the relay activated during a load dump.
Relay Driver
Drive capability of both devices is the same. Free wheeling diode protection is internal to both devices. The free
wheeling voltage is 2Vbe for the UAA1041 and 3Vbe for the IL33193. This results in a higher clamp voltage across the
relay and thus in a faster turn–off. In addition, the lower “on” state supply current is lower on the IL33193 and thus the
voltage drop across the ground resistor R3 is reduced. This results in an even higher clamp voltage across the relay.
Oscillator Phase
The oscillator phase is opposite on the IL33193 as compared to the UAA1041. The Oscillator voltage is falling
during “on” state and rising during “off” state for the IL33193.
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