
308
8023F–AVR–07/09
ATmega325P/3250P
26.5
System and Reset Characterizations
26.6
Standard Power-on Reset
This implementation of power-on reset existed in early versions of ATmega325P/3250P. The
table below describes the characteristics of this power-on reset and it is valid for the following
devices, only:
ATmega325P revision B and older
ATmega3250P revision B and older
Note:
1. The Power-on Reset will not work unless the supply voltage has been below VPOT (falling)
26.7
Enhanced Power-on Reset
This implementation of power-on reset exists in newer versions of ATmega325P/3250P. The
table below describes the characteristics of this power-on reset and it is valid for the following
devices only:
ATmega325P revision C and newer
ATmega3250P revision C and newer
Table 26-3.
Reset, Brown-out, and Internal Voltage Reference Characteristics
Symbol
Parameter
Condition
Min
Typ
Max
Units
VRST
RESET Pin Threshold Voltage
VCC = 3V
0.2 VCC
0.85 VCC
V
tRST
Minimum pulse width on RESET Pin
V
CC = 3V
800
ns
VHYST
Brown-out Detector Hysteresis
50
mV
tBOD
Min Pulse Width on Brown-out Reset
2
s
VBG
Bandgap reference voltage
V
CC = 2.7V,
TA = 25°C
1.0
1.1
1.2
V
tBG
Bandgap reference start-up time
VCC = 2.7V,
T
A = 25°C
40
70
s
IBG
Bandgap reference current consumption
VCC = 2.7V,
TA = 25°C
15
A
Table 26-4.
Reset, Brown-out, and Internal Voltage Reference Characteristics,
TA = -40°C to 85°C
Symbol
Parameter
Min
Typ
Max
Units
VPOT
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
SRON
Power-on Slope Rate
0.01
4.5
V/ms