For the most efficient use of these two control lines,

E should be decoded and used as the primary

device selecting function, while G should be made

a common connection to all devices in the array

and connected to the READ line from the system

control bus.

This ensures 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 Considerations

The power switching characteristics of fast

EPROMs require careful decoupling of the devices.

are of interest to the system designer: the standby

current level, the active current level, and transient

current peaks that are produced by the falling and

rising edges of E. The magnitude of the transient

current peaks is dependent on the capacitive and

inductive loading of the device at the output. The

associated transient voltage peaks can be sup-

pressed by complying with the two line output

control and by properly selected decoupling ca-

pacitors. It is recommended that a 1

µF ceramic

of low inherent inductance and should be placed

as close to the device as possible. In addition, a

4.7

µF bulk electrolytic capacitor should be used

bulk capacitor should be located near the power

supply connection point. The purpose of the bulk

capacitor is to overcome the voltage drop caused

by the inductive effects of PCB traces.

Programming

When delivered (and after each erasure for UV

EPROM), all bits of the M2764A are in the “1" state.

Data is introduced by selectively programming ”0s"

into the desired bit locations. Although only “0s” will

be programmed, both “1s” and “0s” can be present

in the data word. The only way to change a “0" to

a ”1" is by ultraviolet light erasure.

The M2764A is in the programming mode when

The data to be programmed is applied, 8 bits in

parallel, to the data output pins. The levels required

for the address and data inputs are TTL.

Fast Programming Algorithm

Fast Programming Algorithm rapidly programs

M2764A EPROMs using an efficient and reliable

method suited to the production programming en-

vironment. Programming reliability is also ensured

as the incremental program margin of each byte is

continually monitored to determine when it has

Mode

E

G

PA9

Q0 - Q7

Read

Data Out

Output Disable

Hi-Z

Program

X

Data In

Verify

Data Out

Program Inhibit

XXX

Hi-Z

Standby

XXX

Hi-Z

Electronic Signature

Codes Out

± 0.5%.

Table 3. Operating Modes

Identifier

A0

Q7

Q6

Q5

Q4

Q3

Q2

Q1

Q0

Hex Data

Manufacturer’s Code

0010

00

00

20h

Device Code

0000

10

00

08h

Table 4. Electronic Signature

DEVICE OPERATION (cont’d)

3/10

M2764A