Browse Prior Art Database

DUAL DIE SIDAC

IP.com Disclosure Number: IPCOM000007422D
Original Publication Date: 1995-Jul-01
Included in the Prior Art Database: 2002-Mar-25
Document File: 2 page(s) / 75K

Publishing Venue

Motorola

Related People

Jeff Holmes: AUTHOR [+2]

Abstract

A SIDAC is a high power breakover diode. It diverts lightning surges away from sensitive elec- tronic components when used as a transient sup- pressor in telephone applications. Lamp starters use the device to generate the high starting voltage pulse. These applications result in turn-on switching stress because of current amplitudes and rates conducted by the SIDAC. The ability of the device to switch on quickly and survive high pulse current ampli- tudes determines device reliability and switching losses.

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MO7VROLA Technical Developments

DUAL DIE SIDAC

by Jeff Holmes and George Templeton

  A SIDAC is a high power breakover diode. It diverts lightning surges away from sensitive elec- tronic components when used as a transient sup- pressor in telephone applications. Lamp starters use the device to generate the high starting voltage pulse. These applications result in turn-on switching stress because of current amplitudes and rates conducted by the SIDAC. The ability of the device to switch on quickly and survive high pulse current ampli- tudes determines device reliability and switching losses.

  Figure 1 shows the design of the thyristor chips used in the construction of the device. The sharp negative resistance characteristic (Figure 2) is highly desirable because it allows the device to be used in low power drain and long duration relaxation oscil- lator applications. It also promotes turn-on switching

speed aiding the handling offast pulses. However, it increases thermal instability and potentially destruc- tive current crowding. In transient suppressor appli- cations, fast turn-on must balance with high hold- ing current (IH) to help the device turn-off following surge. These requirements tend to be mutually exclu- sive and make it more difficult to build robust devices.

  This invention describes the use of two series connected chips in a single axial lead DO-50 pack- age (Figure 3). This halves the switching dissipa- tion in each chip and allows the use of chips wit...