Browse Prior Art Database

Variable Constant Voltage Constant Wattage Constant Current AC/DC Adapter

IP.com Disclosure Number: IPCOM000115159D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 4 page(s) / 65K

Publishing Venue

IBM

Related People

Narita, I: AUTHOR

Abstract

Disclosed is an AC/DC adapter which can vary its voltage and current characteristics according to the signal from the outside of the adapter. With this AC/DC adapter, Notebook PC system can get the necessary voltage and current from the AC/DC adapter by the signal.

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Variable Constant Voltage Constant Wattage Constant Current AC/DC
Adapter

      Disclosed is an AC/DC adapter which can vary its voltage and
current characteristics according to the signal from the outside of
the adapter.  With this AC/DC adapter, Notebook PC system can get the
necessary voltage and current from the AC/DC adapter by the signal.

      Fig. 1 shows a conventional Constant Voltage Constant Wattage
Constant Current (CVCWCC) AC/DC adapter's characteristics.  In the
Notebook PC, the characteristics of the Constant Voltage and the
Constant Current of the AC/DC adapter is mainly decided by the
battery pack of the Notebook PC.  Because the battery pack is charged
using this characteristics.  So, if the new product supports a new
battery pack, the AC/DC adapter will be developed to charge that
battery pack.  But if the AC/DC adapter can change its Constant
Voltage and Constant Current, the same AC/DC adapter can be used to
charge the different battery packs.  So, this invention is useful for
the AC/DC adapter's commonality between the products.

      Fig. 2 shows the control circuit for the CVCWCC
characteristics.  There are dedicated operational amplifiers for CV,
CW and CC mode.  The inputs of the operational amplifiers are the
reference voltage and the feedback signals.  In the previous CVCWCC
AC/DC adapter, the reference voltage was fixed and can't be changed
from the external signals.  If the reference voltages can be changed
by the exter...