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CIRCUIT FOR REDUCING STANDBY POWER FOR A MEMORY DEVICE

IP.com Disclosure Number: IPCOM000005452D
Original Publication Date: 1982-Jan-01
Included in the Prior Art Database: 2001-Oct-10
Document File: 1 page(s) / 51K

Publishing Venue

Motorola

Related People

Lal Sood: AUTHOR

Abstract

On a printed circuit board (PCS) populated with a number of memory devices, only a Small number are in an active state at a time. It is, therefore, advantageous to reduce standby power requirements of the in- active memory devices. Not only does this contribute in reduced heat dissipation costs, but also results in a reduction of system (PCS) bussing and associated components requirement.

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Technical Developments Volume 2 January 1982

CIRCUIT FOR REDUCING STANDBY POWER FOR A MEMORY DEVICE By Lal Sood

INTRODUCTION

   On a printed circuit board (PCS) populated with a number of memory devices, only a Small number are in an active state at a time. It is, therefore, advantageous to reduce standby power requirements of the in- active memory devices. Not only does this contribute in reduced heat dissipation costs, but also results in a reduction of system (PCS) bussing and associated components requirement.

CIRCUIT DESCRIPTION

   Each memory device has a chip enable input CS. When this input is enabled, the memory device is switched between the standby and active mode of operation. In a static type of memory device, a majority of the standby power is used by the array portion of the total chip. The array's contribution becomes even larger for higher density SRAMs, e.g., 16K and 64K.

   Figure 1 shows a circuit interposed between the power supply and the array for accomplishing such a reduction. During the standby mode, CS is low which turns off MOSFET 01. The array side is then clamped to a lower voltage (Vin - 3 diode drops thru 02, Q3 and Q4). MOSFETS Q2, 03 and Q4 are fairly small compared to MOSFET Ql. In a zero threshold process Ql is a zero threshold device. Otherwise CS should be raised at least one enhancement threshold above the Vin supply voltage by bootstrapping to avoid reducing the array voltage in the active mode.

SUMMARY

    A power saving circuit for a...