ATTINY24 Datasheet, PDF (178/238 Pages) ATMEL Corporation – 8-bit AVR Microcontroller with 2/4/8K Bytes In-System Programmable Flash

Two versions of power-on reset have been implemented, as follows.
20.5.1
Standard Power-On Reset
This implementation of power-on reset existed in early versions of ATtiny24/44/84. The table
below describes the characteristics of this power-on reset and it is valid for the following devices,
only:
• ATtiny24, revision D, and older
• ATtiny44, revision C, and older
• ATtiny84, revision A
Note: Revisions are marked on the package (packages 14P3 and 14S1: bottom, package 20M1: top)
Table 20-5. Characteristics of Standard Power-On Reset. T_A = -40 to +85°C
Symbol Parameter
Min⁽¹⁾
Typ⁽¹⁾ Max⁽¹⁾
V_POR
V_POA
Release threshold of power-on reset ⁽²⁾
Activation threshold of power-on reset ⁽³⁾
0.7
1.0
1.4
0.05
0.9
1.3
SR_ON Power-on slope rate
0.01
4.5
Notes:
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.
Units
V
V
V/ms
20.5.2
Enhanced Power-On Reset
This implementation of power-on reset exists in newer versions of ATtiny24/44/84. The table
below describes the characteristics of this power-on reset and it is valid for the following devices,
only:
• ATtiny24, revision E, and newer
• ATtiny44, revision D, and newer
• ATtiny84, revision B, and newer
Table 20-6. Characteristics of Enhanced Power-On Reset. T_A = -40 to +85°C
Symbol Parameter
Min⁽¹⁾
Typ⁽¹⁾ Max⁽¹⁾
V_POR
V_POA
Release threshold of power-on reset ⁽²⁾
Activation threshold of power-on reset ⁽³⁾
1.1
1.4
1.6
0.6
1.3
1.6
SR_ON Power-On Slope Rate
0.01
Notes:
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.
Units
V
V
V/ms
178 ATtiny24/44/84
8006J–AVR–08/10