ALTERNATOR VOLTAGE CONTROL COMPLETE FAULT DIAGNOSTICS DRIVES 3 W LAMP DIRECTLY LAMP SHORT CIRCUIT PROTECTION SENSING INTERRUPT PROTECTION 100 V DUMP PROTECTION 300 V LOW ENERGY SPIKE PROTECTION THERMAL PROTECTION
DESCRIPTION The is an integrated circuit designed for use with an NPN darlington as a voltage regulator in a threephase alternator charging system. It includes fault diagnostic circuitry which drives 3 W warning lamp in fault conditions such as open or short circuit connections. Protection against load dump transients, short circuits and low energy spikes is incorporated. BLOCK DIAGRAM
Symbol VD Tj Ptot Tstg Top Parameter Operating supply Voltage (through RS) Dump Voltage Junction Temperature Range Power Dissipation at Tamb = 80°C Junction and Storage Temperature Range Operating Temperature Range Value to 125 Unit W °C
Symbol Parameter Max Value 50 Unit °C/W Rth j-alumina(*) Thermal Resistance Junction-alumina
Note : Soldered on PC board that simulates an application with medium device density on board. Thermal resistance junction-pins with the chip soldered on the middle of an alumina supporting substrate measuring 0.65 mm thickness and infinite heathsink.
N° 1 Name Alternator Voltage Sensing Functions Connection for voltage regulation sensing. The regulation sensitivity is a function of R1 and is given R1 A capacitor connected between these two pins filters the feedback signal from the regulated output. Typically the input impedance is 15K. When this pin is left open circuit the overvoltage threshold is a described in the specification. Typically the warning lamp is switched on when the voltage at this pin is greater than 3.5V. This threshold can be modified with a resistor between either the ground or pin 2. This pin must be connected to ground. This pin drives the external darlington disabling it by shorting the current B to ground. These pins must be left floating. Supply Voltage Input A 7.5V (typical) Zener is present at the input. A capacitor connected to ground sets the frequency of the internal oscillator. The frequency is given by : fosc 12 13 GND Lamp Driver 8.4 x Cosc
GND Darlington Driver N.C. IC Supply Voltage Oscillator Capacitor
This pin must be connected to ground. Current Driver for External Lamp for Diagnostics. Internally protected agains short circuits (current limiting), load dump transients and, by means of a zener, against low energy spikes. Not connected. Connection for no charge sensing from the alternator. The internal low threshold is typically 2.4V. By means of the external divider R3/R4 the threshold can be adjusted to give the required sensitivity. Connection for Voltage Battery Sensing This pin senses a failure of the alternator-battery lead as the voltage difference VA-VS. The external resistor R2 limits the current in overvoltage protection.