Browse Prior Art Database

SPLIT REDUNDANT IMPLEMENTATION OF DUAL CLOCK DEVICES

IP.com Disclosure Number: IPCOM000006210D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2001-Dec-13
Document File: 1 page(s) / 45K

Publishing Venue

Motorola

Related People

Scott Robb: AUTHOR

Abstract

An IC (e.g. ASK, microprocessor, etc.) that has a primary oscillator input, a secondary oscillator input, and a clock output (Figure l), can be combined with one or more similar devices to reduce the number of oscillator circuits needed for fail-safe operation by uti- lizing the clock output signals of the complementary device(s).

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MOldROLA INC. Technical Developments Volume 13 July 1991

SPLIT REDUNDANT IMPLEMENTATION

OF DUAL CLOCK DEVICES -

by Scott Robb

  An IC (e.g. ASK, microprocessor, etc.) that has a primary oscillator input, a secondary oscillator input, and a clock output (Figure l), can be combined with one or more similar devices to reduce the number of oscillator circuits needed for fail-safe operation by uti- lizing the clock output signals of the complementary device(s).

  The primary oscillator provides the necessary sig- nal for the IC to perform timing functions or execute instructions. The secondary oscillator provides a sig- nal for the IC in the event of a primary oscillator fail- ure. The IC will select the oscillator signal, primary or

secondary, based on internal criteria and generate the clock output based on the selected oscillator. The clock output signal is used to drive any external device requiring a clock (e.g. UART, ASIC, etc.).

When two such ICs are used concurrently, the

resulting circuit contains four oscillator circuits. By changing this configuration, using the clock output signal of IC A as the secondary oscillator source (1) of IC B and the clock output signal of IC B as the sec- ondary oscillator source of IC A (2), both of the sec- ondary oscillator circuits can be eliminated without losing any redundancy features. (see Figure 2.)

aOCk Output

IC *

Figure 1. Stand alone ConSgmation

Figure 2. Split Redundant Configuration

0 M010r01a. 1°C. 1991 91

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