µPD61P24

18

17. WRITING, READING, AND VERIFYING ONE-TIME PROM (PROGRAM MEMORY)

To write, read, or verify the PROM, set the PROM mode and use the pins shown in Table 17-1. No address input

pin is used. To update the address, the clock signal input from the CLK pin is used.

Table 17-1. Pins Used to Write, Read, and Verify Program Memory

Symbol

Function

Applies program voltage (12.5 V)

CLK

Inputs clock to update address

MD0-MD3

Selects operation mode

D0-D7

Inputs/outputs 8-bit data

Applies supply voltage (6 V)

17.1

Operation Mode When Writing, Reading, and Verifying Program Memory

The

In this mode, the operation modes listed in Table 17-2 can be selected by using the MD0 through MD3 pins.

Any input pins not used for writing, reading, or verifying the program memory must be open or connected to GND

via a pull-down resistor (470

Ω).

Table 17-2. Operating Mode When Writing, Reading, and Verifying Program Memory

Specifies Operation Mode

Operation Mode

MD0

MD1

MD2

MD3

+12.5 V

+6 V

H

L

H

L

Clears program memory address to 0

L

H

H

H

Write mode

L

L

H

H

Read and verify modes

H

×

H

H

Program inhibit mode

×: don’t care (L or H)