6

Am27C040

FI NAL

common connection to all devices in the array and con-

nected to the READ line from the system control bus.

This assures that all deselected memory devices are in

their low-power standby mode and that the output pins

are only active when data is desired from a particular

memory device.

System Applications

During the switch between active and standby condi-

tions, transient current peaks are produced on the ris-

ing and falling edges of Chip Enable. The magnitude of

these transient current peaks is dependent on the out-

put capacitance loading of the device. At a minimum, a

0.1 µF ceramic capacitor (high frequency, low inherent

inductance) should be used on each device between

to overcome the voltage drop caused by the inductive

effects of the printed circuit board traces on EPROM ar-

rays, a 4.7 µF bulk electrolytic capacitor should be used

tion of the capacitor should be close to where the

power supply is connected to the array.

MODE SELECT TABLE

Note:

Mode

CE#/PGM#

OE#

A0

A9

Outputs

Read

XX

X

Output Disable

X

X

X

HIGH Z

Standby (TTL)

X

X

X

X

HIGH Z

Standby (CMOS)

X

X

X

X

HIGH Z

Program

XX

Program Verify

XX

Program Inhibit

XX

X

HIGH Z

Auto Select

(Note 3)

Manufacturer Code

X

01h

Device Code

X

9Bh