Precautions
M30240 Group
Rev.1.00 Sep 24, 2003 Page 117 of 360
1.3 Usage Precautions
1.3.1 Precautions
1.3.1.1 A-D Converter
Connect a capacitor between: the V
REF
pin and the AVss pin; AVcc pin and AVss pin; and each analog
input pin and AVss pin.
• Write to each bit (except bit 6) of A-D control register 0, to each bit of A-D control register 1, and to
bit 0 of A-D control register 2 when A-D conversion is stopped (before a trigger occurs). In particular,
when the V
REF
connection bit is changed from “0” to “1”, start A-D conversion after a lapse of 1µs or
longer.
• When changing A-D operation mode, select analog input pin again.
• Using one-shot mode or single sweep mode
Read the corresponding A-D register after confirming the A-D conversion is finished. (It is known by A-D con-
version interrupt request bit.)
• Using repeat mode, repeat sweep mode 0 or repeat sweep mode 1
Use the undivided main clock as the internal CPU clock.
1.3.1.2 Built-in PROM version
• All built-in PROM versions
High voltage is required to program to the built-in PROM. Be careful not to apply excessive voltage. Be espe-
cially careful during power-on.
• One Time PROM version
One Time PROM versions shipped in blank, of which built-in PROMs are programmed by users, are also pro-
vided. For these microcomputers, a programming test and screening are not performed in the assembly pro-
cess and the following processes. To improve their reliability after programming, we recommend to program
and test as flow shown in Figure 1.114 before use.
Wiring for the Vpp pin of the One-Time PROM version should be as follows (Vpp pin is also used as the CNVss
pin):
• Make the length of wiring between the Vpp pin and Vss pin or Vcc pin the shortest possible.
• When the wiring length has to be longer, connect an approximately 5K ohm resistor in series from the Vpp
pin to the Vss pin or Vcc pin with the shortest possible wiring. This is because the Vpp pin is the power
source input pin for the built-in PROM. When programming in the built-in PROM, the impedance of the Vpp
pin is low to allow the electric current for wiring flow into the PROM. Because of this, noise can enter easily.
If noise enters the Vpp pin, abnormal instruction codes or data are read from the built-in PROM which may
cause a program runaway.
Figure 1.114: Programming and test flow for One-time PROM (OTP) version
Programming with PROM programmer
Screening (Note)
(Leave at 150 C for 40 hours)
Verify test PROM programmer
Function check in target device
Note: Never expose to 150 C exceeding 100 hours.
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