Browse Prior Art Database

Incident Protection Circuit for Card Mis-insertion

IP.com Disclosure Number: IPCOM000015739D
Original Publication Date: 2002-Apr-04
Included in the Prior Art Database: 2003-Jun-21
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Abstract

When a revised SCSI standard is published, a new SCSI Disk Drive Enclosure is always developed to meet it. In such a case, KEY PIN of PCB (Printed Circuit Board) and mechanical structures of a new enclosure for preventing PCB from mis-insertion should like to be the same figure as the old one, to reduce the cost.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 75% of the total text.

Page 1 of 2

Incident Protection Circuit for Card Mis-insertion

    When a revised SCSI standard is published, a new SCSI Disk Drive Enclosure is always developed to meet it. In such a case, KEY PIN of PCB (Printed Circuit Board) and mechanical structures of a new enclosure for preventing PCB from mis-insertion should like to be the same figure as the old one, to reduce the cost.

Circuits are provided for effectively meeting this requirement. A SCSI Disk Drive Enclosure is composed of IF (Interface card), BP (Back Plane), and, PSU (Power Supply Unit). IF, PSU, and, Disk Drives, are inserted into BP. IF receives SCSI signals from a host computer and transfers them to Disk Drives. PSU has outputs of AUX, +5V, and, +12V. AUX is supplied to BP, and, +5V is supplied to IF and Disk Drives through BP, and, +12V is supplied to Disk Drives through BP. AUX is always ON when AC is supplied to PSU. PSU has not only the ON-OFF lever switch but the input named +PSU_ON from BP. +5V and +12V outputs become ON only when the ON-OFF lever switch is ON and +PSU_ON input is active (high).

Circuits are provided for SCSI standard-A and SCSI-standard-B as Fig.1.

SCSI standard-A

SCSI standard-B

1

[This page contains 2 pictures or other non-text objects]

Page 2 of 2

Fig.1. Circuit Diagram

Pin#0 is open and Pin#1 is connected to GND in IF-A. On the other hand, in IF-B Pin#0 is connected to GND and Pin#1 is open. The base of the transistor on BP-A is connected to Pin#1 and that on BP-B is connected to Pin#0...