AT87C54X2-3CSUL View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

AT87C54X2-3CSUL

8-bit CMOS Microcontroller 16/32 Kbytes ROM/OTP

Atmel Corporation 

The encryption array cannot be directly verified. Verification of the encryption array is done by

observing that the code array is well encrypted.

Figure 17-2. Programming and Verification Signal’s Waveform

A0-A12

D0-D7

ALE/PROG

EA/VPP

Control

signals

12.75V

5V

0V

Programming Cycle

Data In

μ 100 s

Read/Verify Cycle

Data Out

17.4

EPROM Erasure (Windowed Packages Only)

Erasing the EPROM erases the code array, the encryption array and the lock bits returning the

parts to full functionality.

Erasure leaves all the EPROM cells in a 1’s state (FF).

17.4.1

Erasure Characteristics

The recommended erasure procedure is exposure to ultraviolet light (at 2537 Å) to an integrated

dose at least 15 W-sec/cm2. Exposing the EPROM to an ultraviolet lamp of 12,000 μW/cm2 rat-

ing for 30 minutes, at a distance of about 25 mm, should be sufficient. An exposure of 1 hour is

recommended with most of standard erasers.

Erasure of the EPROM begins to occur when the chip is exposed to light with wavelength

shorter than approximately 4,000 Å. Since sunlight and fluorescent lighting have wavelengths in

this range, exposure to these light sources over an extended time (about 1 week in sunlight, or 3

years in room-level fluorescent lighting) could cause inadvertent erasure. If an application sub-

jects the device to this type of exposure, it is suggested that an opaque label be placed over the

window.

18. Signature Bytes

The TS87C54/58X2 has four signature bytes in location 30h, 31h, 60h and 61h. To read these

bytes follow the procedure for EPROM verify but activate the control lines provided in Table 31.

for Read Signature Bytes. Table 18-1. shows the content of the signature byte for the

TS80C54/58X2.

40 AT/TS8xC54/8X2

4431E–8051–04/06

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