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Browse Prior Art Database

Integrated Over-Temperature and Short-Circuit Protection

IP.com Disclosure Number: IPCOM000022640D
Original Publication Date: 2004-Apr-25
Included in the Prior Art Database: 2004-Apr-25
Document File: 1 page(s) / 18K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

Integrated driver circuits can be damaged when exposed to a short circuit and over-temperature of client applications, like a telephone line, an antenna, a transformer, motor or other types of user interfaces. State of the art temperature protection circuits have a temperature sensitive element, e.g. an on-chip resistor, fed by a reference circuit. The reference current can be generated externally or internally. Short-circuit protection is usually based on a current sensing device, like a small transistor, which is connected in parallel with the output transistor. When the current exceeds a certain threshold, the output is throttled or turned off. These protection circuits must have a high noise immunity to prevent interruptions under normal conditions. The here proposed solution combines temperature and short-circuit protection in the same circuitry. The temperature sensing elements consist of two pn-junctions and one resistor. These elements are placed directly under the high current metal path, so that, if a short circuit occurs, the temperature in the device immediately increases and a comparator can quickly switch off the output. Also, the reference current is generated internally and in close connection to the temperature sensing element, thus providing noise immunity.

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Integrated Over-Temperature and Short-Circuit Protection

Idea: Lars Karlsson, SE-Kista; Bo Bokinge, SE-Kista; Stefan Barkaroe, SE-Kista; Torbjoern Randahl, SE-Kista; Carl-Mikael Johansson, SE-Kista

Integrated driver circuits can be damaged when exposed to a short circuit and over-temperature of client applications, like a telephone line, an antenna, a transformer, motor or other types of user interfaces. State of the art temperature protection circuits have a temperature sensitive element, e.g. an on-chip resistor, fed by a reference circuit. The reference current can be generated externally or internally. Short-circuit protection is usually based on a current sensing device, like a small transistor, which is connected in parallel with the output transistor. When the current exceeds a certain threshold, the output is throttled or turned off. These protection circuits must have a high noise immunity to prevent interruptions under normal conditions.

The here proposed solution combines temperature and short-circuit protection in the same circuitry. The temperature sensing elements consist of two pn-junctions and one resistor. These elements are placed directly under the high current metal path, so that, if a short circuit occurs, the temperature in the device immediately increases and a comparator can quickly switch off the output. Also, the reference current is generated internally and in close connection to the temperature sensing element, thus providing noise i...