Circuit arrangement for illuminating operating unit in motor vehicle, has voltage source to supply pulse width modulated voltage, where duty cycle of pulse width modulated voltage is longer than that of pulse width modulated signal

摘要

The arrangement has a power output circuit including a voltage source that supplies a pulse width modulated voltage (PWM1), a LED (L) and a transistor (T). The transistor switches the power output circuit, where a constant voltage (U k) or another pulse width modulated signal (PWM2) lies at a base of the transistor. A duty cycle of the pulse width modulated voltage is longer than a duty cycle of the pulse width modulated signal. The voltage (PWM1) and the signal (PWM2) are synchronized, such that the duty cycle of the signal lies completely in the duty cycle of the voltage (PWM1).