M27V322-150P1 データシートの表示（PDF） - STMicroelectronics

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M27V322-150P1

32 Mbit (2Mb x16) Low Voltage UV EPROM and OTP EPROM

STMicroelectronics 

M27V322

Figure 8. Programming Flowchart

VCC = 6.25V, VPP = 12V

SET MARGIN MODE

n=0

NO

++n

= 25

YES

E = 50µs Pulse

NO

VERIFY

YES

++ Addr

FAIL

Last NO

Addr

YES

RESET MARGIN MODE

CHECK ALL WORDS

1st: VCC = 5V

2nd: VCC = 3V

AI03059B

PRESTO III Programming Algorithm

The PRESTO III Programming Algorithm allows

the whole array to be programed with a guaran-

teed margin in a typical time of 100 seconds. Pro-

gramming with PRESTO III consists of applying a

sequence of 50µs program pulses to each word

until a correct verify occurs (see Figure 8). During

programing and verify operation a MARGIN

MODE circuit must be activated to guarantee that

each cell is programed with enough margin. No

overprogram pulse is applied since the verify in

MARGIN MODE provides the necessary margin to

each programmed cell.

Program Inhibit

Programming of multiple M27V322s in parallel

with different data is also easily accomplished. Ex-

cept for E, all like inputs including GVPP of the par-

allel M27V322 may be common. A TTL low level

pulse applied to a M27V322's E input and VPP at

12V, will program that M27V322. A high level E in-

put inhibits the other M27V322s from being pro-

grammed.

Program Verify

A verify (read) should be performed on the pro-

grammed bits to determine that they were correct-

ly programmed. The verify is accomplished with

GVPP at VIL. Data should be verified with tELQV af-

ter the falling edge of E.

On-Board Programming

The M27V322 can be directly programmed in the

application circuit. See the relevant Application

Note AN620.

Electronic Signature

The Electronic Signature (ES) mode allows the

reading out of a binary code from an EPROM that

will identify its manufacturer and type. This mode

is intended for use by programming equipment to

automatically match the device to be programmed

with its corresponding programming algorithm.

The ES mode is functional in the 25°C ± 5°C am-

bient temperature range that is required when pro-

gramming the M27V322. To activate the ES mode,

the programming equipment must force 11.5V to

12.5V on address line A9 of the M27V322, with

VPP = VCC = 5V. Two identifier bytes may then be

sequenced from the device outputs by toggling ad-

dress line A0 from VIL to VIH. All other address

lines must be held at VIL during Electronic Signa-

ture mode.

Byte 0 (A0 = VIL) represents the manufacturer

code and byte 1 (A0 = VIH) the device identifier

code. For the STMicroelectronics M27V322, these

two identifier bytes are given in Table 4 and can be

read-out on outputs Q0 to Q7.

ERASURE OPERATION (applies to UV EPROM)

The erasure characteristics of the M27V322 is

such that erasure begins when the cells are ex-

posed to light with wavelengths shorter than ap-

proximately 4000 Å. It should be noted that

sunlight and some type of fluorescent lamps have

wavelengths in the 3000-4000 Å range. Research

shows that constant exposure to room level fluo-

rescent lighting could erase a typical M27V322 in

about 3 years, while it would take approximately 1

week to cause erasure when exposed to direct

sunlight. If the M27V322 is to be exposed to these

types of lighting conditions for extended periods of

time, it is suggested that opaque labels be put over

the M27V322 window to prevent unintentional era-

sure. The recommended erasure procedure for

M27V322 is exposure to short wave ultraviolet

light which has a wavelength of 2537 Å. The inte-

grated dose (i.e. UV intensity x exposure time) for

erasure should be a minimum of 30 W-sec/cm2.

The erasure time with this dosage is approximate-

ly 30 to 40 minutes using an ultraviolet lamp with

12000 µW/cm2 power rating. The M27V322

should be placed within 2.5cm (1 inch) of the lamp

tubes during the erasure. Some lamps have a filter

on their tubes which should be removed before

erasure.

9/13

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