68HC705SP7 datasheet(186/230 Pages) FREESCALE

186 / 230 page

EPROM/OTPROM

General Release Specification

MC68HC705JJ7/MC68HC705JP7 — Rev. 3.0

EPROM/OTPROM

13.4.2 EPMSEC Programming

The state of the EPMSEC security bit should be programmed using the

programmer board. To program the EPMSEC bit, the desired state must

be written to the COP address and then the MPGM bit in the EPROG

EPMSEC bit:

1. Write the desired data to bit 7 of the COP location ($1FF0).

2. Apply the programming voltage to the IRQ/VPP pin.

3. Set the MPGM bit in the EPROG.

4. Wait for the programming time, tMPGM.

5. Clear the MPGM bit in the EPROG.

6. Remove the programming voltage from the IRQ/VPP pin.

Once the EPMSEC bit has been programmed to a logical one, access to

the contents of the EPROM and MOR in the expanded non-user modes

will be denied. It is therefore recommended that the user EPROM and

MOR in the part first be programmed and fully verified before setting the

EPMSEC bit.

13.5 EPROM Erasing

MCUs with windowed packages permit EPROM erasure with ultraviolet

light. Erase the EPROM by exposing it to 15 Ws/cm2 of ultraviolet light

with a wavelength of 2537 angstroms. Position the ultraviolet light

source 1 inch from the window. Do not use a shortwave filter. The erased

state of an EPROM bit is a logic zero.

NOTE:

Unlike many commercial EPROMs, an erased EPROM byte will read as

$00. All unused locations should be programmed as zeros.

Freescale Semiconductor, Inc.

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