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

Switch Mode Power Supply for CRT Display

IP.com Disclosure Number: IPCOM000038622D
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 2 page(s) / 62K

Publishing Venue

IBM

Related People

Evans, CN: AUTHOR [+3]

Abstract

In a CRT color display, a switch mode power supply is normally run at a multiple of horizontal scan frequency. To eliminate interference effects which may occur when an inexact multiple is present, accurate frequency multiplication is required and is provided in this disclosure by a voltage-controlled oscillator in a phase-locked loop. A commercially available power supply control module is used which includes a phase detector, the oscillator and a pulse-width modulator. One phase detector input is derived from horizontal flyback. This disclosure is applicable for any switched mode power supply topology and is particularly suitable for optimizing power supplies using MOSFETs as the primary switch. Higher operating frequencies result in smaller energy storage components and faster power supply response, i.e.

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 2

Switch Mode Power Supply for CRT Display

In a CRT color display, a switch mode power supply is normally run at a multiple of horizontal scan frequency. To eliminate interference effects which may occur when an inexact multiple is present, accurate frequency multiplication is required and is provided in this disclosure by a voltage-controlled oscillator in a phase- locked loop. A commercially available power supply control module is used which includes a phase detector, the oscillator and a pulse-width modulator. One phase detector input is derived from horizontal flyback. This disclosure is applicable for any switched mode power supply topology and is particularly suitable for optimizing power supplies using MOSFETs as the primary switch. Higher operating frequencies result in smaller energy storage components and faster power supply response, i.e., improvements in cost and performance. Testing has shown that accurate synchronization to a multiple of line rate is necessary, as it has proved very difficult to eliminate beating effects between the two frequencies and front of screen interference when unsynchronized.

(Image Omitted)

The phase-locked loop circuit used is shown in Fig. 1, and the typical waveforms in Fig. 2. The sync pulse is derived from the horizontal flyback pulse and fed to pin 2 of the TDA2582 power supply control module including a phase detector, voltage controlled oscillator (VCO) and pulse-width modulator (PWM). When this input is high, a current source inside the module is enabled, the polarity of which is dependent on the level of the signal on pin 3. The waveform on pin 3 is derived from the power supply transformer wavefor...