
188
8197C–AVR–05/11
ATtiny261A/461A/861A
19.4.2
External Clock Drive
Figure 19-2. External Clock Drive Waveforms
19.5
System and Reset Characteristics
Notes:
1. Not tested. Values are guidelines, only.
VIL1
VIH1
Table 19-3.
External Clock Drive Characteristics
Symbol
Parameter
VCC = 1.8 - 5.5V
VCC = 2.7 - 5.5V
VCC = 4.5 - 5.5V
Units
Min.
Max.
Min.
Max.
Min.
Max.
1/tCLCL
Clock Frequency
0
4
0
10
0
20
MHz
tCLCL
Clock Period
250
100
50
ns
tCHCX
High Time
100
40
20
ns
tCLCX
Low Time
100
40
20
ns
tCLCH
Rise Time
2.0
1.6
0.5
s
tCHCL
Fall Time
2.0
1.6
0.5
s
Δt
CLCL
Change in period from one clock cycle to the next
2
%
Table 19-4.
Reset, Brown-out, and Internal Voltage Characteristics
Symbol
Parameter
Condition
Min
Typ
Max
Units
VRST
RESET Pin Threshold Voltage
0.2 VCC
0.9 VCC
V
tRST
Min pulse width on RESET Pin
V
CC = 3V
2.5
s
VHYST
Brown-out Detector Hysteresis
50
mV
tBOD
Min Pulse Width on
Brown-out Reset
2s
VBG
Internal bandgap voltage
V
CC = 2.7V
TA =25°C
1.0
1.1
1.2
V
tBG
Internal bandgap start-up time
V
CC = 5V
T
A =25°C
40
70
s
IBG
Internal bandgap reference
current consumption
VCC = 5V
T
A =25°C
15
A