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
