Datasheet

228
ATmega8A [DATASHEET]
8159E–AVR–02/2013
Notes: 1. R should be in the range 3 k - 100 k, and C should be at least 20 pF. The C values given in the table includes pin
capacitance. This will vary with package type.
2. The frequency will vary with package type and board layout.
26.5 System and Reset Characteristics
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 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 = 1 and BODLEVEL = 0 for ATmega8A.
Table 26-2. External RC Oscillator, Typical Frequencies
R [k]
(1)
C [pF] f
(2)
33 22 650kHz
10 22 2.0MHz
Table 26-3. Reset, Brown-out and Internal Voltage Reference Characteristics
Symbol Parameter Condition Min Typ Max Units
V
POT
Power-on Reset Threshold Voltage
(rising)
(1)
1.4 2.3 V
Power-on Reset Threshold Voltage
(falling)
1.3 2.3 V
V
RST
RESET Pin Threshold Voltage 0.2 0.9 V
CC
t
RST
Minimum pulse width on RESET Pin 1.5 µs
V
BOT
Brown-out Reset Threshold Voltage
(2)
BODLEVEL = 1 2.40 2.60 2.90
V
BODLEVEL = 0 3.70 4.00 4.50
t
BOD
Minimum low voltage period for Brown-
out Detection
BODLEVEL = 1 2 µs
BODLEVEL = 0 2 µs
V
HYST
Brown-out Detector hysteresis 130 mV
V
BG
Bandgap reference voltage 1.15 1.23 1.35 V
t
BG
Bandgap reference start-up time 40 70 µs
I
BG
Bandgap reference current consumption 10 µs