M27C512 datasheet(5/22 Pages) STMICROELECTRONICS

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M27C512

Device operation

5/22

Device operation

The modes of operations of the M27C512 are listed in the Operating Modes table. A single

power supply is required in the read mode. All inputs are TTL levels except for GVPP and

12V on A9 for Electronic Signature.

2.1

Read mode

The M27C512 has two control functions, both of which must be logically active in order to

obtain data at the outputs. Chip Enable (E) is the power control and should be used for

device selection. Output Enable (G) is the output control and should be used to gate data to

the output pins, independent of device selection. Assuming that the addresses are stable,

the address access time (tAVQV) is equal to the delay from E to output (tELQV). Data is

available at the output after a delay of tGLQV from the falling edge of G, assuming that E has

been low and the addresses have been stable for at least tAVQV-tGLQV.

2.2

Standby mode

The M27C512 has a standby mode which reduces the active current from 30mA to 100µA

The M27C512 is placed in the standby mode by applying a CMOS high signal to the E input.

When in the standby mode, the outputs are in a high impedance state, independent of the

GVPP input.

Table 3.

Operating modes(1)

X = V

IH or VIL, VID = 12V ± 0.5V.

Mode

GVPP

Q7-Q0

Read

VIL

Data Out

Output Disable

VIL

VIH

Hi-Z

Program

VIL Pulse

VPP

Data In

Program Inhibit

VIH

VPP

Hi-Z

Standby

VIH

Hi-Z

Electronic Signature

VIL

VID

Codes

Table 4.

Electronic Signature

Identifier

Hex Data

Manufacturer’s

Code

VIL

001

0000

20h

Device Code

VIH

001

1110

3Dh

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