ATMEGA8_14 Datasheet, PDF (38/331 Pages) ATMEL Corporation – High-performance, Low-power Atmel

Figure 14. Reset Logic
ATmega8(L)
DATA BUS
MCU Control and Status
Register (MCUCSR)
BODEN
BODLEVEL
Brown-Out
Reset Circuit
Pull-up Resistor
SPIKE
FILTER
2486AA–AVR–02/2013
Watchdog
Oscillator
Clock
CK
Generator
CKSEL[3:0]
SUT[1:0]
Delay Counters
TIMEOUT
Table 15. Reset Characteristics
Symbol Parameter
Condition
Min Typ Max Units
V_POT
Power-on Reset Threshold
Voltage (rising)⁽¹⁾
Power-on Reset Threshold
Voltage (falling)
1.4 2.3
V
1.3 2.3
V_RST
t_RST
RESET Pin Threshold Voltage
Minimum pulse width on
RESET Pin
0.2
0.9
V_CC
1.5 µs
V_BOT
Brown-out Reset Threshold
Voltage⁽²⁾
BODLEVEL = 1 2.4 2.6 2.9
V
BODLEVEL = 0 3.7 4.0 4.5
Minimum low voltage period for BODLEVEL = 1
2
t_{BOD Brown-out Detection}
BODLEVEL = 0
2
µs
V_HYST Brown-out Detector hysteresis
130
mV
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
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