Datasheet
373
2549O–AVR–05/12
ATmega640/1280/1281/2560/2561
31.5.2 Enhanced Power-On Reset
This implementation of power-on reset exists in newer versions of
ATmega640/1280/1281/2560/2561. The table below describes the characteristics of this power-
on reset and it is valid for the following devices only:
• ATmega640: revision B and newer
• ATmega1280: revision B and newer
• ATmega1281: revision B and newer
• ATmega2560: revision F and newer
• ATmega2561: revision F and newer
Table 31-5. Characteristics of Enhanced Power-On Reset. T
A
= -40 to +85°C.
Notes: 1. Values are guidelines only.
2. Threshold where device is released from reset when voltage is rising.
3. The power-on reset threshold voltage (falling) will not work unless the supply voltage has been
below V
POT
.
Note: 1. 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 V
CC
= V
BOT
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 = 110 for 4MHz operation of ATmega640V/1280V/1281V/2560V/2561V, BODLEVEL = 101 for 8MHz operation
of ATmega640V/1280V/1281V/2560V/2561V and ATmega640/1280/1281, and BODLEVEL = 100 for 16MHz operation of
ATmega640/1280/1281/2560/2561.
31.6 2-wire Serial Interface Characteristics
Table 31-7 on page 374 describes the requirements for devices connected to the 2-wire Serial
Bus. The ATmega640/1280/1281/2560/2561 2-wire Serial Interface meets or exceeds these
requirements under the noted conditions.
Timing symbols refer to Figure 31-6 on page 375.
Symbol Parameter Min.
(1)
Typ.
(1)
Max.
(1)
Units
V
POT
Power-on Reset Threshold Voltage (rising)
(2)
1.1 1.4 1.6 V
Power-on Reset Threshold Voltage (falling)
(3)
0.6 1.3 1.6 V
V
PSR
Power-On Slope Rate 0.01 V/ms
Table 31-6. BODLEVEL Fuse Coding
(1)
BODLEVEL 2:0 Fuses Min V
BOT
Typ V
BOT
Max V
BOT
Units
111 BOD Disabled
110 1.7 1.8 2.0
V101 2.5 2.7 2.9
100 4.1 4.3 4.5
011
Reserved
010
001
000