HD6433644R datasheet(181/549 Pages) RENESAS

181 / 549 page

Section 6 ROM

Rev. 6.00 Sep 12, 2006 page 161 of 526

REJ09B0326-0600

• Oscillation must have stabilized (following the elapse of the oscillation settling time) or

be stopped.

When the VCC power is turned on, hold the RES pin low for the duration of the

oscillation settling time*2 (trc = 20 ms) before applying VPP.

• The MCU must be in the reset state, or in a state in which reset has ended normally

(reset has been released) and flash memory is not being accessed.

Apply or release VPP either in the reset state, or when the CPU is not accessing flash

memory (when a program in on-chip RAM or external memory is executing). Flash

memory data cannot be read normally at the instant when VPP is applied or released, so

do not read flash memory while VPP is being applied or released.

For a reset during operation, apply or release VPP only after the RES pin has been held

low for at least 10 system clock cycles (10

φ).

• The P and E bits must be cleared in the flash memory control register (FLMCR).

When applying or releasing VPP, make sure that the P or E bit is not set by mistake.

• There must be no program runaway.

When VPP is applied, program execution must be supervised, e.g. by the watchdog

timer.

These power-on and power-off timing requirements for VCC and VPP should also be

satisfied in the event of a power failure and in recovery from a power failure. If these

requirements are not satisfied, overprogramming or overerasing may occur due to program

runaway, etc., which could cause memory cells to malfunction.

b. The VPP flag is set and cleared by a threshold decision on the voltage applied to the FVPP

pin. The threshold level is approximately in the range from VCC +2 V to 11.4 V.

When this flag is set, it becomes possible to write to the flash memory control register

(FLMCR) and the erase block registers (EBR1 and EBR2), even though the VPP voltage

may not yet have reached the programming voltage range of 12.0 V ±0.6 V.

Do not actually program or erase the flash memory until VPP has reached the programming

voltage range.

The programming voltage range for programming and erasing flash memory is 12.0 V ±0.6

V (11.4 V to 12.6 V). Programming and erasing cannot be performed correctly outside this

range. When not programming or erasing the flash memory, insure that the VPP voltage

does not exceed the VCC voltage. This will prevent unintentional programming and erasing.

Notes: 1. Definitions of VPP application, release, and cut-off are as follows:

Application:

Raising the voltage from VCC to 12.0 V ±0.6 V

Release:

Dropping the voltage from 12.0 V ±0.6 V to VCC

Cut-off:

Halting voltage application (floating state)

2. The time depends on the resonator used; refer to the electrical characteristics.

HD6433644R Datasheet(PDF) 181 Page - Renesas Technology Corp

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