308
2545M–AVR–09/07
28.5 System and Reset Characteristics
Note: 1. The Power-on Reset will not work unless the supply voltage has been below V
POT
(falling)
Notes: 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 and BODLEVEL = 101 for ATmega48V/88V/168V, and BODLEVEL = 101 and BODLEVEL = 100 for
ATmega48/88/168.
Table 28-3. Reset, Brown-out and Internal voltage Characteristics
Symbol Parameter Condition Min Typ Max Units
V
POT
Power-on Reset Threshold Voltage (rising) 0.7 1.0 1.4 V
Power-on Reset Threshold Voltage (falling)
(1)
0.05 0.9 1.3 V
V
PSR
Power-on Slope Rate 0.01 4.5 V/ms
V
RST
RESET Pin Threshold Voltage 0.2 V
CC
0.9 V
CC
V
t
RST
Minimum pulse width on RESET Pin 2.5 µs
V
HYST
Brown-out Detector Hysteresis 50 mV
t
BOD
Min Pulse Width on Brown-out Reset 2 µs
V
BG
Bandgap reference voltage
V
CC
=2.7
T
A
=25°C
1.0 1.1 1.2 V
t
BG
Bandgap reference start-up time
V
CC
=2.7
T
A
=25°C
40 70 µs
I
BG
Bandgap reference current consumption
V
CC
=2.7
T
A
=25°C
10 µA
Table 28-4. 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
