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Method for adjustable personal computer power-supply rails

IP.com Disclosure Number: IPCOM000007978D
Publication Date: 2002-May-09
Document File: 6 page(s) / 65K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for adjustable personal computer (PC) power-supply rails. Benefits include improved usability.

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Method for adjustable personal computer power-supply rails

Disclosed is a method for adjustable personal computer (PC) power-supply rails. Benefits include improved usability.

Background

              Conventional power-supply architectures for desktop PC systems rely on a specified, fixed number of DC power rails being delivered from a power supply unit (PSU) to a motherboard (MB). Specified rails for ATX/µATX desktop systems include: 3.3V, 5V, 12V, -5V, -12V, and 5V-standby. The definition of these rails and how the PSU connects to the motherboard is defined in and inherent to the ATX motherboard spec. Some of these DC rails are used natively by the MB and system peripherals. However, other voltage domains exist on conventional and future MB designs. These other voltages support advanced silicon process devices and must be generated by on-board voltage regulators. For example, chipset core voltages are in the range of 1.2V - 1.5V nominal. This low voltage chipset supply is usually generated from either the 3.3-V or 5V DC rail by an on-board voltage regulator.

              In general, silicon process generations change more frequently than industry specifications for motherboards and PSU standards.

Description

              The disclosed method uses the PSU to provide one or more adjustable DC rails as outputs. There are at least two different low-cost methods available for a MB to inform the PSU what DC rail(s) is/are desired.  

Method 1:  The motherboard provides a voltage identification code (VID) to the PSU prior to system power-on indicating what the required target voltage on the adjustable rail is. The PSU decodes the VID data and delivers a stable DC voltage on a set number of output pins.

The VID mechanism is a serial VID(sVID) stream delivered from an EEPROM or some other device on the MB (see Figure 1). Conventionally, in ATX platforms the PSU is controlled by a signal PS_ON# delivered from the MB to the PSU. When all voltages are within a certain percentage of their nominal value, the PSU generates a signal back to the MB called PWR_OK (see Figure 2). This mechanism is maintained in conjunction with the provisions for an sVID stream and adjustable DC rail (see Figure 3). The sVID codes must be flexible enough to apply across several process and technology generations (see Figure 4).

Method 2:  The motherboard provides a reference voltage to the PSU prior to system power-on indicating wh...