Browse Prior Art Database

DC/DC Converter Output Voltage Control by Suspend Signal

IP.com Disclosure Number: IPCOM000116610D
Original Publication Date: 1995-Oct-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Narita, I: AUTHOR

Abstract

Disclosed is a power supply unit which can change its output voltage by suspend signal. It is known that the power consumption of a notebook Personal Computer (PC) becomes smaller while the driving voltage (Vcc) of Large Scale Integrated circuit (LSIs) becomes lower. For example, the power consumption of Complementary Metal Oxide Semiconductor (CMOS) LSIs is proportional to the square of the Vcc. Therefore, it is important to minimize the Vcc. However, in the normal operation mode, the output of the DC/DC converter is set to the value with the margin for the distribution loss and the load regulation. On the other hand, in the suspend mode, the power consumption becomes very small, and there is very little distribution loss and load regulation voltage drop.

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DC/DC Converter Output Voltage Control by Suspend Signal

      Disclosed is a power supply unit which can change its output
voltage by suspend signal.  It is known that the power consumption of
a notebook Personal Computer (PC) becomes smaller while the driving
voltage (Vcc) of Large Scale Integrated circuit (LSIs) becomes lower.
For example, the power consumption of Complementary Metal Oxide
Semiconductor (CMOS) LSIs is proportional to the square of the Vcc.
Therefore, it is important to minimize the Vcc.  However, in the
normal operation mode, the output of the DC/DC converter is set to
the value with the margin for the distribution loss and the load
regulation.  On the other hand, in the suspend mode, the power
consumption becomes very small, and there is very little distribution
loss and load regulation voltage drop.  So, the output voltage of the
DC/DC converter becomes higher than the specified minimum voltage of
the LSIs (for example, 4.75V minimum).  This invention sets the
output voltage of the DC/DC converter lower during the suspend mode
than the normal operation mode.

      The Figure shows the circuit implementing this invention.
Assume that the feedback signal is compared with 2.5V in the DC/DC
converter.  If suspend# signal is high (normal operation mode), the
DC/DC converter regulates its output to become 5.0V.  If suspend#
signal becomes low (suspend mode), SW1 becomes ON and R3 is connected
parallel to R1.  So, the output voltage of the DC...