Atmel AVR AT90CAN32 User Manual

54
7679H–CAN–08/08
AT90CAN32/64/128
Figure 7-4. External Reset During Operation
7.1.5 Brown-out Detection
AT90CAN32/64/128 has an On-chip Brown-out Detection (BOD) circuit for monitoring the V
CC
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
BOT+
=
V
BOT
+ V
HYST
/2 and V
BOT-
= V
BOT
- V
HYST
/2.
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. The test is performed using
BODLEVEL = 010 for Low Operating Voltage and BODLEVEL = 101 for High Operating Volt-
age .
When the BOD is enabled, and V
CC
decreases to a value below the trigger level (V
BOT-
in Figure
7-5), the Brown-out Reset is immediately activated. When V
CC
increases above the trigger level
CC
Table 7-2. BODLEVEL Fuse Coding
(1)
BODLEVEL 2..0 Fuses Min V
BOT
Typ V
BOT
Max V
BOT
Units
111 BOD Disabled
110 4.1 V
101 4.0 V
100 3.9 V
011 3.8 V
010 2.7 V
001 2.6 V
000 2.5 V
Table 7-3. Brown-out Characteristics
Symbol Parameter Min. Typ. Max. Units
V
HYST
Brown-out Detector Hysteresis 70 mV
t
BOD
Min Pulse Width on Brown-out Reset 2 µs

Atmel AVR AT90CAN32 Specifications

General

Brand	Atmel
Model	AVR AT90CAN32
Category	Microcontrollers
Language	English