Motorola Corporation

Joseph V DeNicholas

Randall C Gray

Paul T Bennett

Michael Garrett Neaves

An open loop current control system for regulating the flow of electrical current in an inductor that utilizes two methods of monitoring the current flow in the inductor. The open loop control system maintains the level of current in the inductor between two boundary levels by switching a boost transistor between an on and an off position based upon the level of current in the inductor. The control system measures the level of current in the inductor when a boost transistor is turned on. When the boost transistor is turned off, the control system determines the time period that is required for the current in the inductor to decay from the upper boundary level to the lower boundary level based upon the measured voltage difference across the inductor.

Open loop inductor current control system and method

A high-side, low-side driver that controls voltage from a voltage source to an inductive or resistive load includes a power transistor with a gate, a source and a drain. The driver is configured in a high-side configuration when the load is connected between the source and ground and the drain is connected to the voltage source and in a low-side configuration when the load is connected between the drain and the voltage source and the source is connected to ground. A gate drive circuit turns the power transistor on and off. The positive clamp circuit is connected to the drain and the voltage source. The positive clamp circuit provides a recirculation path for inductive energy that is stored in the inductive load when a loss of reverse battery condition occurs or when ground is lost. A negative clamp circuit that is connected to the source and ground provides a recirculation path for inductive energy that is stored in the inductive load when a loss of reverse battery condition occurs and when battery voltage is lost in the high-side configuration. The power transistor is preferably an isolated lateral double-diffused metal oxide semiconductor field effect transistor (ILDMOSFET). A current limit circuit includes lateral NPN transistors. Multiple drivers may be integrated into a single chip for controlling voltage to multiple inductive loads.

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Phoenix, AZ, United States of America

Joseph V DeNicholas