28.5 System and Reset Characteristics
Table 28-3. Reset, Brown-out and Internal voltage Characteristics
Symbol
Parameter
Condition
Min
0.7
Typ
1.0
0.9
Max
1.4
Units
V
Power-on Reset Threshold Voltage (rising)
Power-on Reset Threshold Voltage (falling)(1)
Power-on Slope Rate
VPOT
0.05
1.3
V
VPSR
VRST
tRST
0.01
4.5
V/ms
V
RESET Pin Threshold Voltage
Minimum pulse width on RESET Pin
Brown-out Detector Hysteresis
Min Pulse Width on Brown-out Reset
0.2 VCC
0.9 VCC
2.5
µs
VHYST
tBOD
50
2
mV
µs
VCC=2.7
TA=25°C
VBG
tBG
IBG
Bandgap reference voltage
1.0
1.1
40
10
1.2
70
V
VCC=2.7
Bandgap reference start-up time
Bandgap reference current consumption
µs
µA
TA=25°C
VCC=2.7
TA=25°C
Note:
1. The Power-on Reset will not work unless the supply voltage has been below VPOT (falling)
Table 28-4. BODLEVEL Fuse Coding(1)
BODLEVEL 2:0 Fuses
Min VBOT
Typ VBOT
BOD Disabled
Max VBOT
Units
111
110
101
100
011
010
001
000
1.7
2.5
4.1
1.8
2.7
4.3
2.0
2.9
4.5
V
Reserved
Notes: 1. VBOT may be below nominal minimum operating voltage for some devices. For devices where this is the case, the device is
tested down to VCC = VBOT during the production test. This guarantees that a Brown-Out Reset will occur before VCC 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.
308
ATmega48/88/168
2545M–AVR–09/07
ATMEL [ ATMEL ]
