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Browse Prior Art Database

Variable Current Controller of Battery Charger

IP.com Disclosure Number: IPCOM000117323D
Original Publication Date: 1996-Feb-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Suzuki, K: AUTHOR

Abstract

Disclosed is a battery charge control circuitry which enables a charger output current variable in accordance with the system power consumption. The Figure shows the present charger system. A power source, an AC adapter 1 in most cases, of the charge system has constant voltage output characteristics. Other circuits are also in the system box of Notebook PC (Personal Computer).

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This is the abbreviated version, containing approximately 100% of the total text.

Variable Current Controller of Battery Charger

      Disclosed is a battery charge control circuitry which enables a
charger output current variable in accordance with the system power
consumption.  The Figure shows the present charger system.  A power
source, an AC adapter 1 in most cases, of the charge system has
constant voltage output characteristics.  Other circuits are also in
the system box of Notebook PC (Personal Computer).

      The AC adapter 1 supplies DC current to both a DC-DC converter
3 and a charger 2.  50m-ohm resistor 4 senses the input DC current,
and a current sense amplifier 5 gains its sense voltage.  An error
amplifier 6 has 2.5V reference on + terminal.  When an output voltage
of current sense amplifier 5, which is inputted to - terminal of the
error amplifier 6, increase to more than 2.5V, the error amplifier 6
outputs a control signal 7 to decrease a charge current 8.

      The battery charger 2 has a control function of the charge
current 8 by the output signal 7 from the error amplifier 6.  Such
charge current balances an input current 9 from the AC Adapter 1 with
its maximum rating.

      Finally, the AC adapter 1 never outputs more than its rating
current level and never goes into its over current mode.  Then, this
system enables to use conventional AC adapter which has only constant
voltage characteristics.