E202075_HD404889 Datasheet, PDF (153/202 Pages) Renesas Technology Corp – Low-Voltage AS Microcomputers with On-Chip LCD Circuit

HD404889/HD404899/HD404878/HD404868 Series
ZTAT^TM Microcomputer with Built-in Programmable ROM
1. Precautions for use of ZTAT^TM microcomputer with built-in programmable ROM
(1) Precautions for writing to programmable ROM built in ZTAT^TM microcomputer
In the ZTAT^TM microcomputer with built-in plastic mold one-time programmable ROM, incomplete
electrical connection between the PROM writer and socket adapter causes writing errors and, makes the
computer unoperatable. To enhance the writing efficiency, attention should be paid to the following points:
(a) Make sure that the socket adapter is firmly fixed to the PROM writer and connected electrically with
each other (neither opened nor shorted), before starting the writing process.
(b) To secure the electrical connection between the contact pin and IC lead, make sure that there is no
foreign substance on the contact pin of the socket adapter, which may cause improper electrical
connection.
(c) When inserting the IC, be careful to protect the IC lead from bending in order to secure the electrical
connection between the contact pin and IC lead. If the lead is bent, correct the bending and insert it
again.
(d) If any trouble is noticed during a blank check to be performed to prevent erroneous writing due to
improper electrical connection, carry out the writing process again according to above steps (a), (b), and
(c).
(e) During the writing process, do not touch the socket adapter and IC to prevent erroneous writing.
(f) To write continuously in the IC, follow steps (a), (b), (c), (d) and (e).
(g) If a writing error recurs, or the rate of writing errors occur frequently, stop writing and check the PROM
writer, socket adapter, etc. for defects.
(h) If any problem is noticed in the written program or in the program after being left at a high temperature,
consult our technical staff.
(2) Precautions when new PROM writer, socket adapter or IC is used
When a new PROM writer, socket adapter or IC is employed, breakdown of the IC may occur or its writing
may become impossible because the noise, overshoot, timing or other electrical characteristics may be
inconsistent with the assured IC writing characteristics. To avoid such troubles, check the following points
before starting the writing process.
(a) To ensure stable writing operation, check that the VCC of the power supplied to the PROM writer,
power source current capacity of VPP, and current consumption at the time of writing to IC are provided
with sufficient margin.
(b) To prevent breakdown of the IC, check that the power source voltage between GND-VCC and GND-
VPP, and overshoot or undershoot of the power source at the connecting terminal of the socket adapter
are within the ratings. Particularly, if the overshoot or undershoot exceeds the maximum rating, the p-n
connection may be damaged, leading to permanent breakdown. If overshoot or undershoot occurs,
recheck the power source damping resistance of capacity.
(c) To prevent breakdown of the IC and for stable writing and reading operation, insert the IC into the
socket adapter and check the power noise between the GND-VCC and GND-VPP near the IC connecting
151