Patent Number: 6,294,905

Title: Method and circuit for controlling current in an inductive load

Abstract: A control or adjusting circuit for a load, a desired signal is compared to an actual signal corresponding to the state of the load, and a PWM control signal is generated in a control signal generating circuit in accordance with the comparison result. The control signal opens and closes a current switch coupled to the load. For forming the PWM control signal, the contents of a ramp counter are compared to the contents of an up/down counter by means of a digital comparator. To obtain fast approximation of the two signals to each other in the case of strong deviations between the desired signal and the actual signal, the up/down counter is subjected to relatively rapid counting in case of high control deviations as compared to low control deviations. To this end, the up/down counter is operated with a clock signal of variable frequency that is produced by a voltage-controlled oscillator as a function of the difference between the desired signal and the actual signal.

Inventors: Schwartz; Reiner (Grafing, DE)

Assignee: STMicroelectronics GmbH

International Classification: H01H 47/22 (20060101); H01H 47/32 (20060101); H03K 17/64 (20060101); H03K 17/60 (20060101); G05F 001/40 ()

Expiration Date: 09/25/2018