Real-time standby voltage adjustment circuit

Details Real-time standby voltage adjustment circuit Real-time standby voltage adjustment circuit

1999-12-28

2001-07-10

Zweizig, Jeffrey (Department: 2816)

Miscellaneous active electrical nonlinear devices, circuits, and

Gating

Converging with plural inputs and single output

C327S541000

Reexamination Certificate

active

06259304

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of personal computers and, more particularly, to a real-time standby voltage adjustment circuit for controlling the power saving modes of personal computers.
2. Description of Related Art
Conventionally, a power saving feature is available in the motherboard of a personal computer (PC) for saving power when the PC is not actively used. A plurality of power saving modes, such as S
0
, S
1
, S
2
, S
3
, S
4
, and S
5
, are defined in the power saving scheme of the PC99 specification. Among these power saving modes, S
0
represents a power on mode. S
1
and S
2
define different standby modes. S
3
represents a suspend to RAM (STR) mode in which data required to reactivate the PC is stored in the RAM of the PC. S
4
represents a suspend to disk (STD) mode in which data required to reactivate the PC is stored in the hard disk of the PC. S
5
represents a power off mode.
The achieve the power saving function, the design of the motherboard circuit and the basic input and output system (BIOS) have to be involved.
FIG. 3
shows a block diagram of a conventional power saving circuit implemented in a motherboard. As shown, this circuit comprises a voltage adjustment circuit
31
, a first switch circuit
32
, a second switch circuit
33
, and a switch control circuit
34
. The voltage adjustment circuit
31
is provided to convert a 5V standby voltage of a power supply (not shown) into a 3.3V standby voltage for being applied to the input of the first switch circuit
32
. The input of the second switch circuit
33
is connected to a 3.3V working voltage of the power supply. The switch control circuit
34
generates two complementary switch control signals for the first switch circuit
32
and the second switch circuit
33
, respectively, based on the power saving control signal provided by the PC system. As such, when the PC is operating in normal condition, the first switch circuit
32
is off and the second switch circuit
33
is on, such that the 3.3V working voltage of the power supply is output. Conversely, if the PC enters a power saving mode, the first switch circuit
32
is on and the second switch circuit
33
is off, such that the 3.3V standby voltage obtained from the voltage adjustment circuit
31
is output. This 3.3V standby voltage thus supplies a minimum power required for the PC to operate in a power saving mode.
Based on progress of the computer technology and the demand for saving power, the newly manufactured motherboards have to meet the requirement of the PC99 specification that involves the functions of the S
0
-S
5
power saving modes. However, many motherboards fail to pass the PC99 certification test and a message of “The system does not support S
4
RTC wake up function, the follow test can't be run” is given. Such a test failure may result from the standby voltage being processed in two stages, that is, sequentially processed by the voltage adjustment circuit
31
and the first switch circuit
32
. Therefore, the output voltage is not stable and the timing of the output voltage may not be correct. Accordingly, there is a strong desire to have a novel circuit for the motherboard to support the S
4
power saving mode and pass the certification test without modifying the BIOS.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a real-time standby voltage adjustment circuit for supplying a very stable standby voltage when a personal computer enters into a power saving mode.
To achieve the object, the real-time standby voltage adjustment circuit includes: a switch control circuit controlled by a power saving control signal provided by the personal computer for generating a switch signal; a switch device controlled by the switch signal for receiving a working voltage provided by a power supply of the personal computer and selectively outputting the same; a converting control circuit; and an adjustment and switch circuit, wherein, the converting control circuit receives an adjust voltage signal generated by the adjustment and switch circuit and is controlled by the power saving control signal for applying the adjust voltage signal back to the adjustment and switch circuit thereby controlling the adjustment and switch circuit to adjust a standby voltage provided by the power supply for outputting an adjusted standby voltage.
The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings.


REFERENCES:
patent: 5157291 (1992-10-01), Shimoda
patent: 5530398 (1996-06-01), Shamlou et al.
patent: 5570061 (1996-10-01), Shimoda
patent: 5886561 (1999-03-01), Eitan et al.
patent: 6035358 (2000-03-01), Tanikawa

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