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Rapid Turnoff Switch

IP.com Disclosure Number: IPCOM000092772D
Original Publication Date: 1967-Jan-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Gladstein, LA: AUTHOR

Abstract

This circuit provides a high current turnoff of precise duration. Transistor T1 is caused to have rapid turnoff by the operation of transistors T2 and T3. An RC circuit comprising C1 and R2 precisely controls the duration of the turnoff pulse. The magnitude of the turnoff pulse is determined by the beta of T3, the input pulse appearing at terminal 10, and the current conducting capabilities of T2.

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Rapid Turnoff Switch

This circuit provides a high current turnoff of precise duration. Transistor T1 is caused to have rapid turnoff by the operation of transistors T2 and T3. An RC circuit comprising C1 and R2 precisely controls the duration of the turnoff pulse. The magnitude of the turnoff pulse is determined by the beta of T3, the input pulse appearing at terminal 10, and the current conducting capabilities of T2.

A bipolar input is provided to terminals 10 and 20. The input can be provided by a conventional current switch not shown. Normally, T1 is on and T2 and T3 are off. When T1 is turned off by the input signal level dropping from +V to 0, T2 and T3 are turned on by the input signal at terminal 10 increasing from 0 to +V. As T3 conducts, capacitor C1 is charged to -V which turns off T3. T2 remains on until the input signal goes to 0. At that time C1 is discharged and T3 continues in a nonconducting condition.

The circuit provides a spike of off current to T1 at the exact time the input of T1 goes to 0. The spike of current provided by T3 can be adjusted in duration and amplitude depending on the application. The circuit does not rob T1 of any on current, thus permitting faster turnon time.

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