JEFFREY KEITH BRAUN, MD
Medical Practice at Warner Rd, Chandler, AZ

4771357, Sep 13, 1988

Jul 23, 1986

6/890259

Stefan Lorincz - Skokie IL
Jeffrey J. Braun - Chandler AZ

Motorola, Inc. - Schaumburg IL

H02H 326

361 87

A power driver including a switch (17) that connects between a power input terminal (12) and a power output terminal (13). A current sense unit (22) provides an over current sense signal if an over current condition should exist with respect to the switch (17). A reference signal unit (23) utilizes a control signal as introduced at a contol signal input (11) to provide a threshold current level signal. A comparator (21) compares the latter two signals and provides an enabling signal to a second switch (19) to disable the switch (17) upon detecting an over current condition. The comparator (21) is enabled by the control signal.

4698582, Oct 6, 1987

Jul 23, 1986

6/889642

Jeffrey J. Braun - Chandler AZ
Kenneth M. Cook - Palatine IL

Motorola, Inc. - Schaumburg IL

G05F 1573

323285

A power driver having a power transistor (15) uses a disable unit (17) to disable the transistor (15) upon sensing a short circuit condition. No current sense resistors are used. The base-emitter voltage of the transistor (15) is compared by a comparator (14) with a reference signal provided by a reference signal unit (16) to determine the existence or absence of a short circuit condition. In the presence of a short circuit, the comparator (14) provides a fault detected signal to the disable unit (17). The disable unit functions to deny the control signal to the transistor (15) and to ground the base of the power transistor (15) to thereby doubly ensure disablement. In addition, the disable unit (17) has memory and will disable the transistor (15) until the control signal recycles.