ATmega128(L)
Figure 22. Reset Logic
DATA BUS
D
L
Q
Q
MCU Control and Status
Register (MCUCSR)
PEN
Pull-up Resistor
Power-On Reset
Circuit
Brown-Out
Reset Circuit
BODEN
BODLEVEL
Pull-up Resistor
SPIKE
FILTER
Reset Circuit
RESET
JTAG Reset
Register
Watchdog
Timer
Watchdog
Oscillator
Delay Counters
Clock
CK
TIMEOUT
Generator
CKSEL[3:0]
SUT[1:0]
Table 19. Reset Characteristics
Symbol Parameter
Condition
Min
Typ
Max
Units
Power-on Reset
Threshold Voltage
1.4
2.3
V
(rising)
VPOT
Power-on Reset
Threshold Voltage
1.3
2.3
V
(falling)(1)
RESET Pin Threshold
Voltage
VRST
0.2 VCC
1.5
0.85 VCC
V
Pulse width on RESET
tRST
Pin
µs
Brown-out Reset
BODLEVEL = 1
BODLEVEL = 0
BODLEVEL = 1
2.4
3.7
2.6
4.0
2
2.9
Threshold Voltage(2)
VBOT
V
4.5
Minimum low voltage
period for Brown-out
Detection
µs
µs
tBOD
BODLEVEL = 0
2
Brown-out Detector
hysteresis
VHYST
100
mV
Notes: 1. The Power-on Reset will not work unless the supply voltage has been below VPOT (falling)
2. VBOT may be below nominal minimum operating voltage for some devices. For devices where
this is the case, the device is tested down to VCC = VBOT during the production test. This guar-
51
2467P–AVR–08/07
ATMEL [ ATMEL ]
