7477 datasheet(40/48 Pages) RENESAS

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MITSUBISHI MICROCOMPUTERS

7477/ 7478 GROUP

SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

PROM READING AND WRITING

Reading

To read the PROM, set the CE and OE pins to “L” level. Input the

address of the data (A0 to A14) to be read and the data will be out-

put to the I/O pins (D0 to D7). The data I/O pins will be floating

when either the CE or OE pin is in the “H” state.

Writing

To write to the PROM, set the OE pin to “H” level. The CPU will en-

ter the program mode when VPP is applied to the VPP pin. The

address to be written to is selected with pins A0 to A14, and the

data to be written is input to pins D0 to D7. Set the CE pin to “L”

level to begin writing.

Note on Writing

When using a PROM programmer, the address range should be

between 400016 and 7FFF16. When data is written between ad-

dresses 000016 and 7FFF16, fill addresses 000016 to 3FFF16 with

FF16.

Erasing

Data can only erased on the M37478E8SS ceramic package,

which includes a window. To erase data on this chip, use an ultra-

violet light source with a 2537 Angstrom wave length. The

minimum radiation power necessary for erasing is 15W · s/cm2.

NOTES ON HANDLING

(1) Sunlight and fluorescent light contain wave lengths capable of

erasing data. For ceramic package types, cover the transpar-

ent window with a seal (provided) when this chip is in use.

However, this seal must not contact the lead pins.

(2) Before erasing, the glass should be cleaned and stains such

as finger prints should be removed thoroughly. If these stains

are not removed, complete erasure of the data could be pre-

vented.

(3) Since a high voltage (12.5V) is used to write data, care should

be taken when turning on the PROM programmer’s power.

(4) For the programmable microcomputer (shipped in One Time

PROM version), Mitsubishi does not perform PROM write test

and screening in the assembly process and following pro-

cesses. To improve reliability after write, performing write and

test according to the flow below before use is recommended.

Writing with PROM programmer

Verify test with PROM programmer

Function check in target device

Screening (Caution) (Leave at 150

°C for 40 hours.)

Caution : Since the screening temperature is higher than storage

temperature, never expose to 150°C exceeding 100

hours.

Read-out

Output disable

Programming

Programming verify

Program disable

Output

Floating

Input

Output

Floating

VIL

VIH

VIL

VIH

VCC

VPP

VCC

VIL

VIH

Mode

VPP

VCC

Data I/O

Note : VIL and VIH indicate an “L” and an “H” input voltage, respectively.

Table 3. I/O signal in each mode

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