ATmega8(L)
Figure 14.
Reset Logic
DATA BUS
MCU Control and Status
Register (MCUCSR)
PORF
BORF
EXTRF
WDRF
BODEN
BODLEVEL
Brown-Out
Reset Circuit
Pull-up Resistor
SPIKE
FILTER
Watchdog
Oscillator
Clock
Generator
CK
Delay Counters
TIMEOUT
CKSEL[3:0]
SUT[1:0]
Table 15.
Reset Characteristics
Symbol
Parameter
Power-on Reset Threshold
Voltage (rising)
V
POT
Power-on Reset Threshold
Voltage (falling)
RESET Pin Threshold Voltage
Minimum pulse width on
RESET Pin
Brown-out Reset Threshold
Voltage
Minimum low voltage period for
Brown-out Detection
Brown-out Detector hysteresis
BODLEVEL = 1
BODLEVEL = 0
BODLEVEL = 1
BODLEVEL = 0
2.4
3.7
2.6
4.0
2
µs
2
130
mV
0.2
Condition
Min
Typ
1.4
1.3
Max
2.3
V
2.3
0.9
1.5
2.9
V
4.5
V
CC
µs
Units
V
RST
t
RST
V
BOT
t
BOD
V
HYST
Notes:
1. The Power-on Reset will not work unless the supply voltage has been below V
POT
(falling)
2. 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 guar-
antees 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 BOD-
LEVEL = 1 for ATmega8L and BODLEVEL = 0 for ATmega8. BODLEVEL = 1 is not applicable
for ATmega8
38
2486AA–AVR–02/2013
ATMEL [ ATMEL CORPORATION ]
