tsc251g1dxxx-l12ced ATMEL Corporation, tsc251g1dxxx-l12ced Datasheet - Page 40

• Manufacturer Part Number: tsc251g1dxxx-l12ced
• Description: 8/16-bit Microcontroller With Serial Communication Interfaces - 32kbytes Rom
• Manufacturer: ATMEL Corporation

Programming and Verifying Non-volatile Memory
Internal Features
EPROM/OTPROM Devices
Mask ROM Devices
ROMless Devices
Security Features
40
AT/TSC8x251G2D
The internal non-volatile memory of the TSC80251G2D derivatives contains five differ-
ent areas:
•
•
•
•
•
All the internal non-volatile memory but the Signature Bytes of the TSC87251G2D prod-
ucts is made of EPROM cells. The Signature Bytes of the TSC87251G2D products are
made of Mask ROM.
The TSC87251G2D products are programmed and verified in the same manner as
Atmel’s TSC87251G1A, using a SINGLE-PULSE algorithm, which programs at
V
of less than 10 seconds for the 32 kilobytes on-chip code memory.
The EPROM of the TSC87251G2D products in Window package is erasable by Ultra-
Violet radiation
reprogramming. The quartz window must be covered with an opaque label
device is in operation. This is not so much to protect the EPROM array from inadvertent
erasure, as to protect the RAM and other on-chip logic. Allowing light to impinge on the
silicon die during device operation may cause a logical malfunction.
The TSC87251G2D products in plastic packages are One Time Programmable (OTP).
An EPROM cell cannot be reset by UV once programmed to zero.
Notes:
All the internal non-volatile memory of TSC83251G2D products is made of Mask ROM
cells. They can only be verified by the user, using the same algorithm as the
EPROM/OTPROM devices.
The TSC80251G2D products do not include on-chip Configuration Bytes, Code Memory
and Encryption Array. They only include Signature Bytes made of Mask ROM cells
which can be read using the same algorithm as the EPROM/OTPROM devices.
In some microcontroller applications, it is desirable that the user’s program code be
secured from unauthorized access. The TSC83251G2D and TSC87251G2D offer two
kinds of protection for program code stored in the on-chip array:
•
•
PP
Code Memory
Configuration Bytes
Lock Bits
Encryption Array
Signature Bytes
Program code in the on-chip Code Memory is encrypted when read out for
verification if the Encryption Array isprogrammed.
A three-level lock bit system restricts external access to the on-chip code memory.
= 12.75V using only one 100μs pulse per byte. This results in a programming time
1. The recommended erasure procedure is exposure to ultra-violet light (at 2537 Å) to
2. Erasure of the EPROM begins to occur when the chip is exposed to light wavelength
an integrated dose of at least 20 W-sec/cm
lamp of 12000 μW/cm
shorter than 4000 Å. Since sunlight and fluorescent light have wavelength in this
range, exposure to these light sources over an extended time (1 week in sunlight or 3
years in room-level fluorescent lighting) could cause inadvertent erasure.
(1)
(UV). UV erasure set all the EPROM memory cells to one and allows
2
rating for 30 minutes should be sufficient.
2
. Exposing the EPROM to an ultra-violet
4135F–8051–11/06
(2)
when the