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Power Down/Operation Mode Switching through Signal Splitter

IP.com Disclosure Number: IPCOM000123044D
Original Publication Date: 1998-Apr-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Miyoshi, A: AUTHOR

Abstract

Disclosed is a method to prevent malfunction of the circuit at switching transition between ON and OFF of the voltage regulater, which mainly supplies the internal circuit with power. In order to eliminate undesirable Idd current of voltage regulater, it is generally required to be shut off at Power Down mode in the core function, while it is waken up at Operation mode. At Power Down mode, instead, the power supply from the external voltage source, Vcc, should be ON to keep specific data in the internal registers.

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Power Down/Operation Mode Switching through Signal Splitter

        Disclosed is a method to prevent malfunction of the circuit
at switching transition between ON and OFF of the voltage regulater,
which mainly supplies the internal circuit with power.  In order to
eliminate undesirable Idd current of voltage regulater, it is
generally required to be shut off at Power Down mode in the core
function, while it is waken up at Operation mode.  At Power Down
mode, instead, the power supply from the external voltage source,
Vcc, should be ON to keep specific data in the internal registers.

        Fig. 1 shows the block diagram with the idea.  Newly designed
Signal Splitter generates signal (1) and (2) from the ONOFF of the
voltage regulater, when (1) and (2) are devised to overlap
ON-condition for a short time on both the voltage regulater and the
power from Vcc.  It brings about prevention of the malfunction like
data missing in  the registers that is likely to be caused by voltage
gap at switching transition of voltage source.  Fig. 2 is the
waveform showing relation  among (1), (2) and ONOFF.

        This method enables power source to the circuit to smoothly
migrate from Vcc to the voltage regulater or the voltage regulater to
Vcc without any functional problem at ON-OFF switching transition.
It leads to cutting off the vain Idd leak of voltage regulater at
Power Down  mode.  Fig. 3 shows the detailed schematic drawing of
Signal Splitter.