Patent ID: 8310194
Filing Date: 2012-11-13
Classification: H03K

Abstract:
1. A load drive device for driving an inductive load by controlling a switching element based on a pulse width modulation (PWM) signal, wherein the switching element is provided in series with the inductive load between a power source and a ground, the load drive device comprising: synchronization control means for outputting the PWM signal to the switching element; a synchronization signal input terminal, through which the synchronization control means is adapted to receive a synchronization signal from an exterior; and a synchronization signal output terminal, through which the synchronization control means is adapted to output the synchronization signal to an exterior, wherein: when the synchronization control means does not receive the synchronization signal through the synchronization signal input terminal, the synchronization control means outputs the synchronization signal through the synchronization signal output terminal such that a first switching period of the PWM signal outputted to the switching element is prevented from overlapping with a second switching period of a PWM signal of an external device; when the synchronization control means receives the synchronization signal through the synchronization signal input terminal, the synchronization control means generates the PWM signal that is outputted to the switching element based on the synchronization signal; the synchronization control means receives a control command for controlling the inductive load, the control command having a PWM format; and when the synchronization control means does not receive the synchronization signal through the synchronization signal input terminal, both of the followings are satisfied: the synchronization control means outputs the PWM signal to the switching element synchronously with the control command; and the synchronization control means outputs a specific PWM signal as the synchronization signal through the synchronization signal output terminal, the specific PWM signal having a frequency and a duty ratio equivalent to a frequency and a duty ratio of the control command.