attiny13-20ss ATMEL Corporation, attiny13-20ss Datasheet - Page 33

• Manufacturer Part Number: attiny13-20ss
• Description: 8-bit Microcontroller With 1k Bytes In-system Programmable Flash - Atmel Corporation
• Manufacturer: ATMEL Corporation

External Reset
Brown-out Detection
2535G–AVR–01/07
An External Reset is generated by a low level on the RESET pin if enabled. Reset
pulses longer than the minimum pulse width (see Table 12) will generate a reset, even if
the clock is not running. Shorter pulses are not guaranteed to generate a reset. When
the applied signal reaches the Reset Threshold Voltage – V
the delay counter starts the MCU after the Time-out period – t
Figure 16. External Reset During Operation
ATtiny13 has an On-chip Brown-out Detection (BOD) circuit for monitoring the V
during operation by comparing it to a fixed trigger level. The trigger level for the BOD
can be selected by the BODLEVEL Fuses. The trigger level has a hysteresis to ensure
spike free Brown-out Detection. The hysteresis on the detection level should be inter-
preted as V
Table 13. BODLEVEL Fuse Coding
Note:
Table 14. Brown-out Characteristics
When the BOD is enabled, and V
in Figure 17), the Brown-out Reset is immediately activated. When V
the trigger level (V
out period t
The BOD circuit will only detect a drop in V
for longer than t
Symbol
V
t
BOD
HYST
BODLEVEL [1..0] Fuses
CC
1. V
devices where this is the case, the device is tested down to V
production test. This guarantees that a Brown-out Reset will occur before V
to a voltage where correct operation of the microcontroller is no longer guaranteed.
TOUT
BOT+
BOT
Parameter
Brown-out Detector Hysteresis
Min Pulse Width on Brown-out Reset
11
10
01
00
BOD
= V
has expired.
may be below nominal minimum operating voltage for some devices. For
BOT+
BOT
given in Table 14.
+ V
in Figure 17), the delay counter starts the MCU after the Time-
HYST
/2 and V
CC
(1)
Min V
decreases to a value below the trigger level (V
BOT-
BOT
CC
= V
if the voltage stays below the trigger level
BOT
Typ V
- V
1.8
2.7
4.3
BOD Disabled
HYST
BOT
Min
/2.
RST
TOUT
Typ
– on its positive edge,
50
Max V
2
– has expired.
CC
CC
increases above
BOT
= V
Max
BOT
during the
CC
CC
Units
Units
mV
V
µs
drops
level
BOT-
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