µPD75P048
3.3 PROM READ PROCEDURE
The PROM contents can be read in the verify mode by using the following procedure: (see the following
figure)
(1) Pull unused pins to VSS through resistors. Set the X1 pin low.
(2) Supply 5 volts to the VDD and VPP pins.
(3) Wait for 10 µs.
(4) Select the clear program memory address mode.
(5) Supply 6 volts to the VDD and 12.5 volts to the VPP pins.
(6) Select the program inhibit mode.
(7) Select the verify mode. Apply four pulses to the X1 pin. Every four clock pulses will output the data stored
in one address.
(8) Select the program inhibit mode.
(9) Select the clear program memory address mode.
(10) Return the VDD and VPP pins back to + 5 volts.
(11) Turn off the power.
The following figure shows steps (2) to (9).
VPP
VPP
VDD
VDD+1
VDD
VDD
X1
P40-P43
P50-P53
Output data
Output data
MD0
(P30)
MD1
(P31)
“L”
MD2
(P32)
MD3
(P33)
16