µ
PD75P308
13
3.3 PROGRAM MEMORY READ PROCEDURE
The contents of the program memory can be read in the following procedure.
(1) Ground the unused pins through pull-down resistors. The X1 pin must be low.
(2) Supply 5 V to the V
DD
and V
PP
pins.
(3) Wait for 10 microseconds.
(4) Set program memory address 0 clear mode.
(5) Supply 6 V to the V
DD
pin and 12.5 V to the V
PP
pin.
(6) Set program inhibit mode.
(7) Set verify mode. Data of each address is sequentially output each time a clock pulse is input to the
X1 pin four times.
(8) Set program inhibit mode.
(9) Set program memory address 0 clear mode.
(10) Change the voltages of V
DD
and V
PP
pins to 5 V.
(11) Turn off the power supply.
Steps (2) to (9) are illustrated below.
V
PP
V
DD
V
DD
+1
V
DD
V
PP
V
DD
Data output
Data output
P40-P43
P50-P53
MD0
(P30)
MD1
(P31)
MD2
(P32)
MD3
(P33)
X1