Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Controlled Slope Power Up Subroutine for a Microprocessor Controlled Switching Power Supply

IP.com Disclosure Number: IPCOM000051711D
Original Publication Date: 1981-Mar-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 3 page(s) / 53K

Publishing Venue

IBM

Related People

Ashley, CL: AUTHOR [+4]

Abstract

An assembly language subroutine is described for use in a microprocesso that is regulating the voltage level of a switching power supply. The routine provides a standardized method of digitally powering up a switching power supply. The subroutine is useful in conjunction with a microprocessor-controlled power supply such as that described in the article appearing on pages 4401-4406.

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 53% of the total text.

Page 1 of 3

Controlled Slope Power Up Subroutine for a Microprocessor Controlled Switching Power Supply

An assembly language subroutine is described for use in a microprocesso that is regulating the voltage level of a switching power supply. The routine provides a standardized method of digitally powering up a switching power supply. The subroutine is useful in conjunction with a microprocessor-controlled power supply such as that described in the article appearing on pages 4401- 4406.

Instead of the computations required for the precise capacitive delays during a linear control power-up, the decision capability of the microprocessor is used to control the nature of this transient period. This algorithm is not dependent on the specifics of transformer design but rather on the behavior of the rising voltage level function.

For a switching power supply, a control pulse-width modulated signal regulates the output voltage level. The longer the duration of the pulse width, the higher the output voltage V-Out is, or: V-Out = V-In (T-On/T) where V-In represents the unregulated power supply bulk voltage, T-On is the control pulse width, and T is the control pulse period.

When the power supply is initially powered up, the output voltage level must be raised to the regulated level sufficiently slowly so as not to greatly overshoot, as a result of the transformer's slow reaction time.

The subroutine designed START 1, shown in the drawing, serves to initially power-up the power supply slowly by controlling the slope of the rising output voltage level. When V-Out does reach the regulated value, the regulation control is shifted to a dynamic regulation routine designated START.

During every logic cycle, START 1 samples the V-Out level by calling subroutine DECS, which returns the value to register R1. DECS is an analog-to- digital conversion routine. If the V-Out level has risen more than two from the previous value (R2), the controlling pulse width (R3) is not increased...