Datasheet

301
2570N–AVR–05/11
ATmega325/3250/645/6450
28.5 System and Reset Characteristics
Notes: 1. The Power-on Reset will not work unless the supply voltage has been below V
POT
(falling)
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 = 10 for Atmel ATmega325/3250/645/6450 and BODLEVEL = 01 for Atmel ATmega325/3250/645/6450V.
Table 28-4. Reset, Brown-out and Internal Voltage Reference Characteristics
Symbol Parameter Condition Min Typ Max Units
V
POT
(1)
Power-on Reset Threshold Voltage (rising) T
A
= -40°C to 85°C 0.7 1.0 1.4 V
Power-on Reset Threshold Voltage (falling)
(1)
T
A
= -40°C to 85°C 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 V
CC
= 3V 0.2V
CC
0.85V
CC
V
t
RST
Minimum pulse width on RESET Pin V
CC
= 3V 800 ns
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
= 2.7V, T
A
= 25°C1.0 1.1 1.2 V
t
BG
Bandgap reference start-up time V
CC
= 2.7V, T
A
= 25°C4070µs
I
BG
Bandgap reference current consumption V
CC
= 2.7V, T
A
= 25°C15 µA
Table 28-5. BODLEVEL Fuse Coding
(1)
BODLEVEL 2:0 Fuses Min V
BOT
Typ V
BOT
Max V
BOT
Units
11 BOD Disabled
10 1.7 1.8 2.0
V01 2.5 2.7 2.9
00 4.1 4.3 4.5