atmega32c1 ATMEL Corporation, atmega32c1 Datasheet - Page 47

• Manufacturer Part Number: atmega32c1
• Description: Atmega32m1 Automotive 8-bit Avr Microcontroller With 32k/64k Bytes In-system Programmable Flash
• Manufacturer: ATMEL Corporation

7.2.3
7647A–AVR–02/08
Brown-out Detection
ATmega32/64/M1/C1 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
V
Table 7-2.
Notes:
Table 7-3.
Notes:
When the BOD is enabled, and V
7-5), the Brown-out Reset is immediately activated. When V
(V
expired.
The BOD circuit will only detect a drop in V
longer than t
Symbol
V
t
BOT
BOD
BOT+
HYST
+ V
BODLEVEL 2..0 Fuses
in
1. V
2. Values are guidelines only.
1. Values are guidelines only.
HYST
Figure
this is the case, the device is tested down to V
antees that a Brown-Out Reset will occur before V
operation of the microcontroller is no longer guaranteed. The test is performed using
BODLEVEL = 010 for Low Operating Voltage and BODLEVEL = 101 for High Operating Volt-
age .
BOD
BOT
/2 and V
BODLEVEL Fuse Coding
Brown-out Characteristics
Parameter
Brown-out Detector Hysteresis
Min Pulse Width on Brown-out Reset
101
100
010
001
000
may be below nominal minimum operating voltage for some devices. For devices where
110
011
111
given in
7-5), the delay counter starts the MCU after the Time-out period t
BOT-
Table
= V
BOT
7-3.
- V
CC
HYST
decreases to a value below the trigger level (V
Min V
(1)(2)
/2.
(1)
BOT
CC
if the voltage stays below the trigger level for
CC
Typ V
= V
ATmega32/64/M1/C1
Min.
2.6
4.3
2.7
4.5
BOT
CC
RESERVED
DISABLED
CC
BOT
during the production test. This guar-
increases above the trigger level
drops to a voltage where correct
Typ.
50
2
Max V
Max.
BOT
BOT-
TOUT
in
Units
Units
mV
BOT+
Figure
V
V
V
µs
has
47
CC
=