iC-JE PDIP8 Sample

Description

iC-JE is a PWM driver for inductive loads, such as relay coils, solenoid valves and small DC motors. The setpoint for the coil current is preset with the help of the RSET external resistor. 60 to 300 mA can be set for energise mode which then automatically drop to 2/3 of this value (40 to 200 mA) during hold mode. The device is switched to hold mode after 100 ms provided that the set coil current is obtained during energizing (PWMOK = 1). The changeover between energise and hold modes is suitable for typical relay drives which require a powerful initial energising current which can then be reduced after closing the air gap in a magnetic circuit. The quadratic dependence on the current intensity means that the power dissipation of the system is more than halved through this reduction. The output current is measured with zero loss at the power transistor’s ON resistance and compared to the setpoint. In order to maintain this setpoint, the switch-on time of the coil driver is modulated by the pulse width. The internal flyback diode maintains the current during the switching pauses. The switching frequency of ca. 80 kHz is provided by the internal oscillator. The device is shutdown by a Low signal at input IN or the removal of the power supply; the current reduction in the coil is suppor ted by the changeover of the free-wheeling circuit. The Zener diode now active permits higher free-wheeling voltages and thus a quicker demagnetising of the coil. The status indicator LED is constantly ON when hold mode is functioning correctly and flashes with low voltage, excessive temperature or when the coil current in energise mode has not reached the set point. The driver output is shutdown with low voltage or excessive temperature. The device is protected against destruction by ESD.

Features