165
ATtiny25/45/85 [DATASHEET]
2586Q–AVR–08/2013
21.5
System and Reset Characteristics
Note:
1. Values are guidelines only.
Two versions of power-on reset have been implemented, as follows.
21.5.1
Standard Power-On Reset
This implementation of power-on reset existed in early versions of ATtiny25/45/85. The table below describes the
characteristics of this power-on reset and it is valid for the following devices, only:
ATtiny25, revision D, and older
ATtiny45, revision F, and older
ATtiny85, revision B, and newer
Note:
Revisions are marked on the package (packages 8P3 and 8S2: bottom, package 20M1: top)
Note:
1. Values are guidelines, only
2. Threshold where device is released from reset when voltage is rising
3. The power-on reset will not work unless the supply voltage has been below VPOA
21.5.2
Enhanced Power-On Reset
This implementation of power-on reset exists in newer versions of ATtiny25/45/85. The table below describes the
characteristics of this power-on reset and it is valid for the following devices, only:
ATtiny25, revision E, and newer
Table 21-4.
Reset, Brown-out and Internal Voltage Characteristics
Symbol
Parameter
Condition
Units
VRST
RESET Pin Threshold Voltage
VCC = 3V
0.2 VCC
0.9 VCC
V
tRST
Minimum pulse width on
RESET Pin
VCC = 3V
2.5
s
VHYST
Brown-out Detector Hysteresis
50
mV
tBOD
Min Pulse Width on
Brown-out Reset
2s
VBG
Bandgap reference
voltage
VCC = 5.5V
TA = 25°C
1.0
1.1
1.2
V
tBG
Bandgap reference
start-up time
VCC = 2.7V
TA = 25°C
40
70
s
IBG
Bandgap reference
current consumption
VCC = 2.7V
TA = 25°C
15
A
Table 21-5.
Characteristics of Standard Power-On Reset. T
A = -40 to +85C
Symbol
Parameter
Units
VPOR
Release threshold of power-on reset
(2)0.7
1.0
1.4
V
VPOA
Activation threshold of power-on reset
(3)0.05
0.9
1.3
V
SRON
Power-on slope rate
0.01
4.5
V/ms