Datasheet

198
8246A–AVR–11/09
ATtiny2313A/4313
21.5 System and Reset Characteristics
Notes: 1. When RESET pin used as reset (not as I/O).
2. Not tested in production.
21.5.1 Enhanced Power-On Reset
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
.
21.5.2 Brown-Out Detection
Note: 1. V
BOT
may be below nominal minimum operating voltage for some devices. For devices where
this is the case, the device is tested down to V
CC
= V
BOT
during the production test. This guar-
antees that a Brown-out Reset will occur before V
CC
drops to a voltage where correct
operation of the microcontroller is no longer guaranteed.
Table 21-3. Reset, Brown-out, and Internal Voltage Characteristics
Symbol Parameter Condition Min Typ Max Units
V
RST
RESET Pin Threshold
Voltage
0.2 V
CC
0.8V
CC
V
t
RST
Minimum pulse width on
RESET Pin
(1)(2)
V
CC
= 1.8 - 5.5V 2.5 µs
V
HYST
Brown-out Detector
Hysteresis
(2)
50 mV
t
BOD
Min Pulse Width on
Brown-out Reset
(2)
2µs
V
BG
Internal bandgap reference
voltage
V
CC
= 2.7V
T
A
= 25°C
1.0 1.1 1.2 V
t
BG
Internal bandgap reference
start-up time
(2)
V
CC
= 2.7V
T
A
= 25°C
40 70 µs
I
BG
Internal bandgap reference
current consumption
(2)
V
CC
= 2.7V
T
A
= 25°C
15 µA
Table 21-4. Characteristics of Enhanced Power-On Reset. T
A
= -40 – 85°C
Symbol Parameter Min
(1)
Typ
(1)
Max
(1)
Units
V
POR
Release threshold of power-on reset
(2)
1.1 1.4 1.6 V
V
POA
Activation threshold of power-on reset
(3)
0.6 1.3 1.6 V
SR
ON
Power-On Slope Rate 0.01 V/ms
Table 21-5. V
BOT
vs. BODLEVEL Fuse Coding
BODLEVEL [1:0] Fuses Min
(1)
Typ
(1)
Max
(1)
Units
11 BOD Disabled
10 1.7 1.8 2.0
V01 2.5 2.7 2.9
00 4.1 4.3 4.5