Renesas 4513 Manual De Usuario

3-26

APPENDIX

3.4 Notes on noise

4513/4514 Group User’s Manual

(5) Wiring to V

pin of One Time PROM version

In the built-in PROM version of the 4513/4514

Group, the CNV

pin is also used as the

built-in PROM power supply input pin V

●

When the V

pin is also used as the

CNV

pin

Connect an approximately 5 k

resistor to

the V

pin the shortest possible in series

a n d a l s o t o t h e V

S S

p i n . W h e n n o t

connecting the resistor, make the length of
wiring between the V

pin and the V

pin the shortest possible (refer to Figure
3.4.5)

Note: Even when a circuit which included an

approximately 5 k

resistor is used in the

Mask ROM version, the microcomputer
operates correctly.

●

Reason

The V

pin of the One Time PROM ver-

sion is the power source input pin for the
built-in PROM. When programming in the
built-in PROM, the impedance of the V

pin is low to allow the electric current for
writing flow into the PROM. Because of
this, noise can enter easily. If noise enters
the V

pin, abnormal instruction codes or

data are read from the built-in PROM, which
may cause a program runaway.

Fig. 3.4.5 Wiring for the V

pin of the One Time

PROM version

CNV

When the V

pin is also used as the CNV

In the shortest
distance

Approximately

3.4.2 Connection of bypass capacitor across V

line and V

line

Connect an approximately 0.1

F bypass capacitor

across the V

line and the V

line as follows:

• Connect a bypass capacitor across the V

and the V

pin at equal length.

• Connect a bypass capacitor across the V

and the V

pin with the shortest possible wiring.

• Use lines with a larger diameter than other signal

lines for V

line and V

line.

• Connect the power source wiring via a bypass

capacitor to the V

pin and the V

pin.

Fig. 3.4.6 Bypass capacitor across the V

line

and the V

line

N.G.

O.K.