Datasheet

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 V
POA
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 Min
(1)
Typ
(1)
Max
(1)
Units
V
RST
RESET Pin Threshold Voltage V
CC
= 3V 0.2 V
CC
0.9 V
CC
V
t
RST
Minimum pulse width on
RESET
Pin
V
CC
= 3V 2.5 µs
V
HYST
Brown-out Detector Hysteresis 50 mV
t
BOD
Min Pulse Width on
Brown-out Reset
2µs
V
BG
Bandgap reference
voltage
V
CC
= 5.5V
T
A
= 25°C
1.0 1.1 1.2 V
t
BG
Bandgap reference
start-up time
V
CC
= 2.7V
T
A
= 25°C
40 70 µs
I
BG
Bandgap reference
current consumption
V
CC
= 2.7V
T
A
= 25°C
15 µA
Table 21-5. Characteristics of Standard Power-On Reset. T
A
= -40 to +85C
Symbol Parameter Min
(1)
Typ
(1)
Max
(1)
Units
V
POR
Release threshold of power-on reset
(2)
0.7 1.0 1.4 V
V
POA
Activation threshold of power-on reset
(3)
0.05 0.9 1.3 V
SR
ON
Power-on slope rate 0.01 4.5 V/ms