UPD75P3018 Datasheet, PDF (30/60 Pages) NEC – 4-BIT SINGLE-CHIP MICROCONTROLLER

µPD75P3018
8. ONE-TIME PROM (PROGRAM MEMORY) WRITE AND VERIFY
The program memory contained in the µPD75P3018 is a 32768 x 8-bit one-time PROM that can be electrically written one
time only. The pins listed in the table below are used for this PROM’s write/verify operations. Clock input from the X1
pin is used instead of address input as a method for updating addresses.
Pin
Function
VPP
Pin where program voltage is applied during program memory
write/verify (usually VDD potential)
X1, X2
Clock input pins for address updating during program memory
write/verify. Input the X1 pin’s inverted signal to the
X2 pin.
MD0-MD3
Operation mode selection pin for program memory write/verify
D0/P40 to D3/P43
(lower 4 bits)
D4/P50 to D7/P53
(upper 4 bits)
8-bit data I/O pins for program memory write/verify
*
VDD
Pin where power supply voltage is applied.
Applies VDD = 2.2 to 5.5 V in normal operation mode and +6 V
for program memory write/verify.
Caution Pins not used for program memory write/verify should be connected to Vss.
8.1 Operation Modes for Program Memory Write/Verify
When +6 V is applied to the VDD pin and +12.5 V to the VPP pin, the µPD75P3018 enters the program memory write/verify
mode. The following operation modes can be specified by setting pins MD0 to MD3 as shown below.
Operation mode specification
VPP
VDD
MD0 MD1
+12.5 V +6 V
H
L
L
H
L
L
H
X
MD2
H
H
H
H
MD3
L
H
H
H
Operation mode
Zero-clear program memory address
Write mode
Verify mode
Program inhibit mode
X: L or H
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