HD404669 Datasheet, PDF (103/142 Pages) Hitachi Semiconductor – Low-Voltage AS Microcomputers with On-Chip DTMF Generation Circuit

HD404669 Series
3. Two levels of program voltages (VPP) are available for the PROM: 12.5 V and 21 V. Our product
employs a V_PP of 12.5 V. If a voltage of 21 V is applied, permanent breakdown of the product will
result. The VPP of 12.5 V is obtained for the PROM writer by setting it according to the Intel 27256
specifications.
Writing/verification
Programming of the built-in program ROM employs a high speed programming method. With this method,
high speed writing is effected without voltage stress to the device or without damaging the reliability of the
written data.
A basic programming flow chart is shown in figure81 and a timing chart in figure82.
For precautions for PROM writing procedure, refer to "ZTAT^TM Microcomputer On-chip Programmable
ROM Characteristics and Usage Notes."
Table 23 Selection of Mode
Pins
Mode
CE
OE
VPP
Writing
“Low”
“High”
VPP
Verification
“High”
“Low”
VPP
Prohibition of programming
“High”
“High”
VPP
O0–O4
Data input
Data output
High impedance
Table 24 PROM Writer Program Address
ROM size
8k
12k
16k
Address
$0000~$3FFF
$0000~$5FFF
$0000~$7FFF
103