HD64F3437TF16 Datasheet, PDF (451/752 Pages) Hitachi Semiconductor – 12 V must not be applied to the S-mask model (single-power-supply specification), as this may permanently damage the device.

High-Speed, High-Reliability Programming: Unused areas of the H8/3434F flash memory
contain H'FF data (initial value). The H8/3434F flash memory uses a high-speed, high-reliability
programming procedure. This procedure provides enhanced programming speed without
subjecting the device to voltage stress and without sacrificing the reliability of programmed data.
Figure 19.15 shows the basic high-speed, high-reliability programming flowchart. Tables 19.15
and 19.16 list the electrical characteristics during programming.
Start
Set V_PP = 12.0 V ±0.6 V
Address = 0
n=0
n+1→n
Program setup command
Program command
Wait (25 µs)
Program-verify command
Address + 1 → address
Wait (6 µs)
Verification?
No go
Go
No
Last address?
Yes
Set V_PP = V_CC
No
n = 20?
Yes
End
Fail
Figure 19.15 High-Speed, High-Reliability Programming
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