Current monitoring in switched mode drivers

Abstract

A switching driver 100 has an output stage 104 with a network of switches 105 for switching an output node 103a, 103b between different switching voltages, and a modulator 106 for controlling a duty-cycle of the switching output stage based on the input signal Sin. The modulator generates a modulator signal Smod based on the input signal. A current monitor 107 receives a first current signal SImon indicative of a sensed first driver current and determines and / or limits a second driver current using the first current signal and the modulator signal. One of the first driver current and the second driver current is an output current IOUT to the load 102 and the other is an input current Iin from a power supply. In one arrangement, the current monitor determines a modulator signal limit for limiting the modulator signal to apply current limiting of the second signal. In another arrangement the switching driver includes a current limiter, and the modulator comprises a quantizer (Fig.2, 202) to generate the switch controls signals and a filter arrangement (Fig.2, 201) to generate the modulator signal based on the input signal and a feedback signal Sfb.

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