AT90USB646 datasheet(59/456 Pages) ATMEL

Part #	AT90USB646

Description	8-bit Atmel Microcontroller with 64/128Kbytes of ISP Flash and USB Controller

PDF	456 Pages

Scroll/Zoom	100%

Manufacturer	ATMEL [ATMEL Corporation]

Direct Link	http://www.atmel.com

Logo

59 / 456 page

7593L–AVR–09/12

AT90USB64/128

voltage invokes the delay counter, which determines how long the device is kept in RESET after

CC rise. The RESET signal is activated again, without any delay, when VCC decreases below

the detection level.

Figure 9-2.

MCU start-up, RESET tied to V

CC.

Figure 9-3.

MCU start-up, RESET extended externally.

Note:

If VPOR or VCCRR parameter range can not be followed, an external reset is required.

9.4

External reset

An External Reset is generated by a low level on the RESET pin. Reset pulses longer than the

minimum pulse width (see Table 9-1 on page 58) will generate a reset, even if the clock is not

running. Shorter pulses are not guaranteed to generate a reset. When the applied signal

reaches the Reset Threshold Voltage – V

RST – on its positive edge, the delay counter starts the

MCU after the Time-out period – t

TOUT – has expired.

RESET

TIME-OUT

INTERNAL

RESET

TOUT

POT

RST

POR

RESET

TIMEOUT

INTERNAL

RESET

TOUT

POT

RST

VCC

POR

AT90USB646 Datasheet(PDF) 59 Page - ATMEL Corporation