PROM_POWER_DOWN

Published:2009/7/3 4:15:00 Author:May | From:SeekIC

Conserves power in applications when data is required from PROM for only small percentage of system cycle. Circult turns PROM off automatically when not needed, with access time increased only by 80-ns delay of power-down circuit. PNP switch can be PN4313 or 2N3467 pass transistor. With two 74S04 sections in series at input, active low selection is obtained. 74S00 at input gives active high selection. When logic input to R2 goes low, PNP switch is turned on and +5V is applied to National DM74S287 256 x 4 PROM.- Memory Applications Handbook, National Semiconductor, Santa Clara, CA, 1978, p 5-9-5-12.



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