ATMEGA169 ATMEL [ATMEL Corporation], ATMEGA169 Datasheet - Page 40

• Manufacturer Part Number: ATMEGA169
• Description: 8-bit Microcontroller with 16K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

External Reset
Brown-out Detection
40
ATmega169/V
An External Reset is generated by a low level on the RESET pin. Reset pulses longer
than the minimum pulse width (see Table 16) 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
counter starts the MCU after the Time-out period – t
Figure 17. External Reset During Operation
ATmega169 has an On-chip Brown-out Detection (BOD) circuit for monitoring the V
level 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
interpreted as V
Table 17. BODLEVEL Fuse Coding
Note:
Table 18. Brown-out Characteristics
Symbol
V
t
BOD
HYST
BODLEVEL 2..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.
The test is performed using BODLEVEL = 110 for ATmega169V.
BOT
Parameter
Brown-out Detector Hysteresis
Min Pulse Width on Brown-out Reset
111
110
101
100
011
010
001
000
BOT+
may be below nominal minimum operating voltage for some devices. For
= V
BOT
+ V
HYST
/2 and V
(1)
Min V
1.7
2.5
4.1
BOT
BOT-
= V
RST
Typ V
TOUT
BOT
1.8
2.7
4.3
BOD Disabled
– on its positive edge, the delay
- V
Reserved
BOT
– has expired.
Min
HYST
/2.
Typ
50
Max V
2
2.0
2.9
4.5
CC
BOT
= V
Max
2514P–AVR–07/06
BOT
during the
CC
Units
Units
mV
µs
V
drops
CC