ATMEGA64-16AI datasheet(53/393 Pages) ATMEL

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ATmega64(L)

2490L–AVR–10/06

Notes:

1. The Power-on Reset will not work unless the supply voltage has been below VPOT

(falling).

2. V

BOT may be below nominal minimum operating voltage for some devices. For

devices where this is the case, the device is tested down to VCC = VBOT during the

production test. This guarantees that a Brown-out Reset will occur before V

CC drops

to a voltage where correct operation of the microcontroller is no longer guaranteed.

The test is performed using BODLEVEL=1 for ATmega64L and BODLEVEL=0 for

ATmega64. BODLEVEL=1 is not applicable for ATmega64.

Power-on Reset

A Power-on Reset (POR) pulse is generated by an On-chip Detection circuit. The detec-

tion level is defined in Table 19. The POR is activated whenever V

CC is below the

detection level. The POR circuit can be used to trigger the Start-up Reset, as well as to

detect a failure in supply voltage.

A Power-on Reset (POR) circuit ensures that the device is reset from Power-on. Reach-

ing the Power-on Reset threshold voltage invokes the delay counter, which determines

how long the device is kept in RESET after V

CC rise. The RESET signal is activated

again, without any delay, when V

CC decreases below the detection level.

Figure 23. MCU Start-up, RESET Tied to V

Figure 24. MCU Start-up, RESET Extended Externally

RESET

TIME-OUT

INTERNAL

RESET

TOUT

POT

RST

RESET

TIME-OUT

INTERNAL

RESET

TOUT

POT

RST

VCC

ATMEGA64-16AI Datasheet(PDF) 53 Page - ATMEL Corporation

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