ATMEGA261 View Datasheet(PDF) - Atmel Corporation
Part Name
Description
MFG CO.
'ATMEGA261' PDF : 226 Pages View PDF
Figure 9-3. MCU Start-up, RESET Extended Externally
VCC
VPOT
9.0.4
RESET
TIME-OUT
INTERNAL
RESET
V RST
t TOUT
Table 9-1. Power On Reset Specifications
Symbol
VPOT
VPORMAX
VPORMIN
VCCRR
VRST
Parameter
Power-on Reset Threshold Voltage (rising)
Power-on Reset Threshold Voltage (falling)(1)
VCC Max. start voltage to ensure internal
Power-on Reset signal
VCC Min. start voltage to ensure internal
Power-on Reset signal
VCC Rise Rate to ensure Power-on Reset
RESET Pin Threshold Voltage
Min
Typ
Max Unit
1.1
1.4
1.7
V
0.8
1.3
1.6
V
0.4
V
-0.1
0.01
0.1 VCC
V
0.9VCC
V/ms
V
Note: 1. Before rising, the supply has to be between VPORMIN and VPORMAX to ensure a Reset.
External Reset
An External Reset is generated by a low level on the RESET pin if enabled. Reset pulses longer
than the minimum pulse width (see “System and Reset Characteristics” on page 190) will gener-
ate 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 – VRST – on its positive
edge, the delay counter starts the MCU after the Time-out period – tTOUT – has expired.
Figure 9-4. External Reset During Operation
CC
42 ATtiny261/ATtiny461/ATtiny861
7753E–AVR–06/10
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