Browse Prior Art Database

Bias Circuit for Power Supply Bus Line

IP.com Disclosure Number: IPCOM000060403D
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Chapman, DB: AUTHOR [+2]

Abstract

In a disk memory device which has provisions for powering off one of two actuators for maintenance purposes, data is handled on the other actuator in the head disk assembly. In powering off an actuator, when a negative voltage supply to the actuator is turned off, the negative voltage bus can be pulled above ground through resistive elements in the circuits by the bias from a positive voltage supply, which may remain on. The two actuators share a common Read/Write Data line and a common servo clock line. If the negative voltage bus rises above ground, or even above -0.8 volt, interference with the data handling capability of the powered actuator is produced by a forward bias on the integrated circuit substrates, which degrades the data, and can even limit the voltage swing, on the Read/Write Data and servo clock lines.

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 62% of the total text.

Page 1 of 2

Bias Circuit for Power Supply Bus Line

In a disk memory device which has provisions for powering off one of two actuators for maintenance purposes, data is handled on the other actuator in the head disk assembly. In powering off an actuator, when a negative voltage supply to the actuator is turned off, the negative voltage bus can be pulled above ground through resistive elements in the circuits by the bias from a positive voltage supply, which may remain on. The two actuators share a common Read/Write Data line and a common servo clock line. If the negative voltage bus rises above ground, or even above -0.8 volt, interference with the data handling capability of the powered actuator is produced by a forward bias on the integrated circuit substrates, which degrades the data, and can even limit the voltage swing, on the Read/Write Data and servo clock lines. Thus, a small, negative bias of at least -0.8 volt must be kept on the negative voltage bus when one actuator is turned off and the other actuator is still powered up. The small negative bias on the negative voltage bus required in circumstances described above is provided by the above circuit. In operation, when the right actuator has been powered off, that power is still present on the left actuator negative voltage bus. In this case, power for regulator circuit R1 is drawn from the left actuator negative voltage supply through diode D1. Regulator circuit R1 provides output voltage, Vreg, equal to one diode...