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EP0166581A2
Expired / Lapsed
EP
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Cmos circuit overvoltage protection
Assignee: AT&T Inc
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Filing: 1985-06-20
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Granted: —
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Expires: 2005-06-20
Abstract
Abstract The novel circuit (10) in accordance with the present invention uses vertical bipolar transistors (84, 80) to carry the overvoltage surge current. The transistors (84, 80) are controlled by a voltage sensing (16-30) and driving arrangement (40-78, 86) which includes means (86) for latching the current-carry bipolar transistors in their conducting state during the cause of the surge. The structure of the vertical bipolar transistors is such that they can be readily incorporated on a CMOS integrated circuit. The transistors of the sensing, latching and driving circuits can than conventiently be in the form of MOS devices and thereby can be provided with better accuracy and in a reduced circuit area.
Inventors
- 👤 Apparajan Ganesan
- 👤 Ronald Andrew Morrison
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 08:12
CPC Classifications
H; H03; H03K; H03K3/00; H03K3/02; H03K3/353; H03K3/356; H03K3/356104; H03K17/00; H03K17/08; H03K17/081; H03K17/0814; H03K17/08142; H10; H10D; H10D89/00; H10D89/60; H10D89/601
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
115 words
A circuit for protecting an electronic circuit from an overvoltage surge between a positive and a negative supply voltage nodes, CHARACTERIZED BY a first vertical bipolar transistor having its emitter-collector path connected between the supply nodes; a second vertical bipolar transistor having its emitter-collector path connected between one of the supply nodes and the base of the first vertical bipolar transistor; a first resistor connected between the base of the first bipolar transistor and the other supply node, and switching means responsive to an overvoltage condition between the supply nodes connected to the base of the second bipolar transistor for turning on the first and second bipolar transistors for the course of the overvoltage condition.
Claim 2
Dependent Claim
115 words
A circuit for protecting an electronic circuit from an overvoltage surge between a positive and a negative supply voltage nodes, CHARACTERIZED BY a first vertical bipolar transistor having its emitter-collector path connected between the supply nodes; a second vertical bipolar transistor having its emitter-collector path connected between one of the supply nodes and the base of the first vertical bipolar transistor; a first resistor connected between the base of the first bipolar transistor and the other supply node, and switching means responsive to an overvoltage condition between the supply nodes connected to the base of the second bipolar transistor for turning on the first and second bipolar transistors for the course of the overvoltage condition.
Claim 3
Dependent Claim
17 words
The circuit as defined in claim 1 CHARACTERIZED IN THAT the switching means includes a latch circuit.
Claim 4
Dependent Claim
49 words
The circuit as defined in claim 2 CHARACTERIZED BY a comparator having one of its input nodes coupled to the activating voltage and its other input node coupled to the input of a current amplifying means which has its output connected to the base of the second bipolar transistor.
Claim 5
Dependent Claim
38 words
The circuit as defined in claim 3 CHARACTERIZED BY positive feedback means connected between a current amplifying means and a sensing means for latching the first and second bipolar transistors in their conducting condition during the overvoltage condition.
Claim 6
Dependent Claim
28 words
The circuit as defined in claim 4 CHARACTERIZED IN THAT the sensing means includes a zener diode connected in series with a sensing resistor between the supply nodes.
Claim 7
Dependent Claim
43 words
The circuit as defined in claim 5 CHARACTERIZED BY a transconductance transistor having its conduction path connected between one supply node and one input of the comparator and a resistor connected between the other supply node and the one input of the comparator.
Claim 8
Dependent Claim
35 words
The circuit as defined in claim 6 CHARACTERIZED IN THAT the transconductance transistor is a third vertical bipolar transistor having a resistor connected between one side of its emitter-collector path and the other supply node.
Claim 9
Dependent Claim
42 words
The circuit as defined in claim 7 CHARACTERIZED IN THAT the current amplifying means includes first and second current mirror transistors having one side of their conduction paths connected to one of the supply nodes and having their control electrodes connected together.
Claim 10
Dependent Claim
56 words
The device as defined in claim 8 CHARACTERIZED IN THAT the positive feedback means comprises a feedback transistor having its current path connected between one of the supply nodes and the common node of the zener diode and the sensing resistor and having its control electrode connected to the control electrodes of the current mirror transistors.
References Cited (Backward Citations)
No citation records indexed.
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