ATMEGA161-8PC View Datasheet(PDF) - Atmel Corporation
Part Name
Description
MFG CO.
ATMEGA161-8PC
Atmel Corporation
'ATMEGA161-8PC' PDF : 159 Pages View PDF
ATmega161(L)
Table 3. Reset Characteristics (VCC = 5.0V)
Symbol Parameter
Condition
Min Typ
Max
Units
VPOT
Power-on Reset Threshold Voltage (rising)
Power-on Reset Threshold Voltage (falling)
BOD disabled
1.0 1.4
1.8
V
BOD enabled
1.7 2.2
2.7
V
BOD disabled
0.4 0.6
0.8
V
BOD enabled
1.7 2.2
2.7
V
VRST
RESET Pin Threshold Voltage
-
-
0.85 VCC
V
VBOT
Brown-out Reset Threshold Voltage
(BODLEVEL = 1)
2.6 2.7
2.8
V
(BODLEVEL = 0)
3.8 4.0
4.2
Note: The Power-on Reset will not work unless the supply voltage has been below VPOT (falling).
‘
Table 4. Reset Delay Selections
CKSEL Start-up Time, VCC = 2.7V,
Start-up Time, VCC = 4.0V,
[2:0]
BODLEVEL Unprogrammed BODLEVEL Programmed Recommended Usage(1)
000
4.2 ms + 6 CK
001
30 µs + 6 CK
5.8 ms + 6 CK
10 µs + 6 CK
External Clock, fast rising power
External Clock, BOD enabled(2)(3)
010
67 ms + 16K CK
92 ms + 16K CK
Crystal Oscillator, slowly rising power
011
4.2 ms + 16K CK
100
30 µs + 16K CK
5.8 ms + 16K CK
10 µs + 16K CK
Crystal Oscillator, fast rising power
Crystal Oscillator, BOD enabled(2)(3)
101
67 ms + 1K CK
92 ms + 1K CK
Ceramic Resonator/External clock, Slowly rising power
110
4.2 ms + 1K CK
5.8 ms + 1K CK
Ceramic Resonator, fast rising power
111
30 µs + 1K CK
10 µs + 1K CK
Ceramic Resonator, BOD enabled(2)(3)
Notes:
1. The CKSEL fuses control only the start-up time. The oscillator is the same for all selections. On power-up, the real-time part
of the start-up time is increased with typ. 0.6ms.
2. Or external power-on reset.
3. When BOD is enabled, there will be a real-time part = 50 µs (typ.)
Table 4 shows the start-up times from reset. From sleep, only the clock counting part of the start-up time is used. The
watchdog oscillator is used for timing the real-time part of the start-up time. The number WDT oscillator cycles used for
each time-out is shown in Table 5.
Table 5. Number of Watchdog Oscillator Cycles
BODLEVEL
Time-out
Number of cycles
Unprogrammed
4.2 ms (at Vcc=2.7V)
1K
Unprogrammed
67 ms (at Vcc=2.7V)
16K
Programmed
5.8 ms (at Vcc=4.0V)
4K
Programmed
92 ms (at Vcc=4.0V)
64K
Note: The bod-level fuse can be used to select start-up times even if the Brown-out detection is disabled (by leaving the BODEN fuse
unprogrammed).
The frequency of the watchdog oscillator is voltage dependent as shown in the Electrical Characteristics section. The
device is shipped with CKSEL = 010.
25
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