iC-GE QFN16

Description

iC-GE is a PWM driver for inductive loads, such as relay coils, solenoid valves and other inductive loads. The setpoints for the coil’s energising and hold current are preset by means of external resistors RACT and RHOLD. These currents can be set in a range from 100 mA to 1 A. The iC-GE intrinsically switches from energising to hold mode after 50 ms provided that the set energising current has been reached. A capacitor at TACT prolongs the time before the switch to hold mode occurs. The changeover between energising 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 cutting the current by half reduces the power dissipation by ca. 75%. Using PWM the output current is controlled to the values set at RACT and RHOLD. The internal ﬂyback diode maintains the current during the switching pauses. The switching frequency of ca. 80 kHz is provided by the internal oscillator. Varying this frequency between 70 kHz and 90 kHz reduces the EMI. The device is shutdown by a Low signal at input EN or the removal of the power supply; the current reduction in the coil is supported 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 setpoint. The driver output is shutdown with low voltage or excessive temperature. Alternatively to using an LED output DIAG signals the correct operating by outputting a high signal. The input signal at EN can be synchronised with the zero crossing at input SYNC. Thus by using an external R/C network, the switching of the coil can be synchronised with the load current of e.g. the relay.

Features