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1477K–AVR–08/10
ATtiny26(L)
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-
antees that a Brown-out Reset will occur before VCC drops to a voltage where correct
operation of the microcontroller is no longer guaranteed. The test is performed using
BODLEVEL=1 for ATtiny26L and BODLEVEL=0 for ATtiny26. BODLEVEL=1 is not applicable
for ATtiny26.
CPU wakes up from Power-down, only the clock counting part of the start-up time is used. The
Watchdog Oscillator is used for timing the real-time part of the start-up time.
Power-on Reset
A Power-on Reset (POR) pulse is generated by an On-chip Detection circuit. The detection level
is defined in Table 16 The POR is activated whenever VCC is below the detection level. The POR circuit can be used to trigger the Start-up Reset, as well as detect a failure in supply voltage.
The Power-on Reset (POR) circuit ensures that the device is reset from Power-on. Reaching the
Power-on Reset threshold voltage invokes a delay counter, which determines the delay, for
which the device is kept in RESET after VCC rise. The time-out period of the delay counter can
be defined by the user through the CKSEL Fuses. The different selections for the delay period
again, without any delay, when the VCC decreases below detection level.
Table 16. Reset Characteristics
Symbol
Parameter
Condition
Min
Typ
Max
Units
VPOT
Power-on Reset Threshold
Voltage (rising)
1.4
2.3
V
Power-on Reset Threshold
1.3
2.3
V
VRST
RESET Pin Threshold Voltage
0.2
0.9
VCC
tRST
Minimum pulse width on
RESET Pin
1.5
s
VBOT
Brown-out Reset Threshold
BODLEVEL = 1
2.4
2.7
2.9
V
BODLEVEL = 0
3.7
4.0
4.5
tBOD
Minimum low voltage period for
Brown-out Detection
BODLEVEL = 1
2
s
BODLEVEL = 0
2
s
VHYST
Brown-out Detector hysteresis
130
mV