μPD75P308

3. WRITING AND VERIFYING PROM (PROGRAM MEMORY)

The program memory of the μPD75P308 is a PROM of 8064 x 8 bits. To write data to or verify the contents of this PROM, the pins listed in the table below are used. Note that no address input pins are provided because the address is updated by the clock input through the X1 pin.

Pin Name

Function

 

 

VPP

Applies voltage when program memory is written/verified (normally, at VDD potential)

 

 

X1, X2

These pins input clock that updates address when program memory is written/verified. To X2 pin,

input signal 180º out of phase in respect to signal to X1 pin.

 

 

 

MD0-MD3

These pins select operation mode when program memory is written/verified.

 

 

P40-P43 (Lower 4)

These pins input/output 8-bit data when program memory is written/verified.

P50-P53 (Upper 4)

 

 

 

VDD

Power supply voltage application pin.

Apply 5V ± 5% to this pin during normal operation and 6V when program memory is written/verified.

 

 

 

Note 1: Always cover the erasure window of the μPD75P308K with a light-opaque film except when the contents of the program memory are erased.

2:The one-time PROM model μPD75P308GF is not equipped with a window and therefore, the contents of the program memory of this model cannot be erased by exposing it to ultraviolet rays.

3.1OPERATION MODES FOR WRITING/VERIFYING PROGRAM MEMORY

When +6V is applied to the VDD pin of the μPD75P308 with +12.5V applied to the VPP pin, the μPD75P308 is set in the program memory write/verify mode. In this mode, the following operation modes can be set by using the MD0-MD3 pins. At this time, pull down the levels of all the other pins to VSS.

 

Operating Mode Specification

 

 

 

Operating Mode

 

 

 

 

 

 

 

 

VPP

VDD

MD0

MD1

MD2

MD3

 

 

 

 

 

 

 

 

 

 

 

 

H

L

H

L

 

 

Program memory address 0 clear mode

 

 

 

 

 

 

 

 

 

+12.5 V

+6 V

L

H

H

H

 

 

Write mode

 

 

 

 

 

 

 

L

L

H

H

 

 

Verify mode

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

H

x

H

H

 

 

Program inhibit mode

 

 

 

 

 

 

 

 

 

 

 

 

 

 

x:

L or H

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NEC PD75P308 user manual Writing and Verifying Prom Program Memory, Operation Modes for WRITING/VERIFYING Program Memory