8

www.fairchildsemi.com

at V

pins, O0 –07 . Proper code access is only guaranteed at 25

°C ±

5

°C.

ERASURE CHARACTERISTICS

The erasure characteristics of the device are such that erasure

begins to occur when exposed to light with wavelengths shorter

than approximately 4000 Angstroms (Å). It should be noted that

sunlight and certain types of fluorescent lamps have wavelengths

in the 3000Å – 4000Å range.

The recommended erasure procedure for the EPROM is expo-

sure to short wave ultraviolet light which has a wavelength of

2537Å. The integrated dose (i.e., UV intensity x exposure time) for

The EPROM should be placed within 1 inch of the lamp tubes

during erasure. Some lamps have a filter on their tubes which

should be removed before erasure.

An erasure system should be calibrated periodically. The distance

from lamp to device should be maintained at one inch. The erasure

time increases as the square of the distance from the lamp (if

distance is doubled the erasure time increases by factor of 4).

Lamps lose intensity as they age. When a lamp is changed, the

distance has changed, or the lamp has aged, the system should

be checked to make certain full erasure is occurring. Incomplete

erasure will cause symptoms that can be misleading. Program-

mers, components, and even system designs have been errone-

ously suspected when incomplete erasure was the problem.

SYSTEM CONSIDERATION

The power switching characteristics of EPROMs require careful

segments that are of interest to the system designer: the standby

current level, the active current level, and the transient current

peaks that are produced by voltage transitions on input pins. The

magnitude of these transient current peaks is dependent on the

transient voltage peaks can be suppressed by properly selected

decoupling capacitors. It is recommended that at least a 0.1

µF

GND. This should be a high frequency capacitor of low inherent

inductance. In addition, at least a 4.7

µF bulk electrolytic capacitor

bulk capacitor should be located near where the power supply is

connected to the array. The purpose of the bulk capacitor is to

overcome the voltage drop caused by the inductive effects of the

PC board traces.

MODE SELECTION

The modes of operation of the NM27C210 are listed in Table 1. A single 5V power supply is required in the read mode. All inputs are

TABLE 1. Modes Selection

Pins

CE

OE

PGM

V

PP

V

CC

Outputs

Mode

Read

X

X

5.0V

(Note 16)

Output Disable

X

V

IH

X

X

5.0V

High Z

Standby

V

IH

X

X

X

5.0V

High Z

Programming

12.75V

6.25V

Program Verify

12.75V

6.25V

Program Inhibit

V

IH

X

X

12.75V

6.25V

High Z

TABLE 2. Manufacturer’s Identification Code

Pins

A0

A9

O7

O6

O5

O4

O3

O2

O1

O0

Hex

(21)

(31)

(12)

(13)

(14)

(15)

(16)

(17)

(18)

(19)

Data

Manufacturer Code

12V

10001111

8F

Device Code

12V

11010110

D6