The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 05, 1991
Filed:
Apr. 19, 1989
Philip N King, Fort Collins, CO (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A driver circuit for use in a circuit board tester which tester can perform both functional and in-circuit tests on a given device under test (DUT). The tester provides a test signal representative of a command for the driver circuit to provide logic high or logic low signals to a given device under test (DUT). The driver includes an output stage for providing desired logic high and logic low signals in response to the test signal; and switch circuitry, connected between the tester and the output stage, for preventing the test signal from reaching the output stage in response to a second control signal. The driver circuit is also shown to include an amplifier which, during operation of the driver circuit, receives feedback from the output stage. In addition, the driver circuit includes another output stage which provides a feedback signal when the driver circuit is in tri-state (deactivated). The driver circuit provides a low output impedance when logic high and logic low signals are being provided and a high output impedance when the driver circuit is in tri-state.