tOSC1
ø
*
2.7 to 5.5 V
VCC
0 µs min
0 µs min
12 ± 0.6 V
VCC + 2 V to 11.4 V
0 µs min
VPP
0 to VCCV
VCCV
Boot mode
Timing at which boot
program branches
to RAM area
12 ± 0.6 V
VPP
0 to VCC
V
VCCV
User program
mode
RES
Min 10ø
(when RES is low)
Periods during which the VPP flag is being set or
cleared and flash memory must not be accessed
Note: * In the LH version, VCC = 3.0 V to 5.5 V.
Figure 19.20 VPP Power-On and Power-Off Timing
(6) Do not apply 12 V to the FVPP pin during normal operation.
To prevent accidental programming or erasing due to microcontroller program runaway etc., apply
12 V to the VPP pin only when the flash memory is programmed or erased, or when flash memory
is emulated by RAM. Overprogramming or overerasing due to program runaway can cause
memory cells to malfunction. Avoid system configurations in which 12 V is always applied to the
FVPP pin.
While 12 V is applied, the watchdog timer should be running and enabled to halt runaway
program execution, so that program runaway will not lead to overprogramming or overerasing.
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RENESAS [ RENESAS TECHNOLOGY CORP ]
