Input detecting circuit used for electric-leakage protection devices with self-diagnostic function

• US 7,598,754 B2
• Filed: 06/18/2007
• Issued: 10/06/2009
• Est. Priority Date: 08/24/2006
• Status: Active Grant

• Current Assignee: Shanghai Fudan Microelectronics Group Company Limited
• Original Assignee: Shanghai Fudan Microelectronics Company Limited
• Inventors: Yu, Jun, Chen, Qikang
• Primary Examiner(s): NGUYEN, HOAI AN D
• Application Number:
  US11/764,588
• Publication Number:
  US 20080048667A1
• Time in Patent Office: 841 Days
• Field of Search: 324/713, 324/691, 324/649, 324/600, 324/522, 324/424, 324/500, 324/512, 324415-423, 324/536, 324/555, 324/76.11, 324/158.1, 361/42, 361/1, 361/102, 361/109, 361/114, 361/115
• US Class Current: 324/713
• CPC Class Codes: H02H 3/335 the main function being self testing of the device

Abstract

An input detecting circuit for an electric-leakage protection device with self-diagnostic function includes an analog electric-leakage unit, a magnetic electric-leakage induction ring, an operational amplifier, and an inverse feedback circuit. The inverse feedback circuit includes a first resistance and a second circuit unit shunted with the first resistance. The second circuit unit includes a second resistance and a unidirectional break-over unit connected in series with the second resistance.

Claims

1. An input detecting circuit for an electric-leakage protection device with self-diagnostic function, comprising:

an emulation electric-leakage unit,

a magnetic leakage current detecting ring,

an amplifying circuit, and

a negative feedback circuit;

wherein;

one end of said negative feedback circuit is connected with an input end of a negative terminal of said amplifying circuit, and the other end is connected with an output end of said amplifying circuit;

said negative feedback circuit contains a first resistance and a second circuit unit parallel with said first resistance;

said second circuit unit contains a second resistance and a unidirectional conductive unit connected in series with the second resistance;

said conductive unit contains at least one unidirectional conductive element.

2. An input detecting circuit as set forth in claim 1, wherein one end of said emulation electric-leakage unit is connected with a forward current, while the other end is connected with a backward current, and the emulation electric-leakage unit is adapted to produce a unidirectional emulation leakage current, which is superimposed to an actual leakage current.