ATmega162 datasheet(50/324 Pages) ATMEL

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2513K–AVR–07/09

ATmega162/V

Brown-out Detection

ATmega162 has an On-chip Brown-out Detection (BOD) circuit for monitoring the V

CC level dur-

ing 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+ =

BOT + VHYST/2 and VBOT- = VBOT - VHYST/2.

Notes:

1. VBOT 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 = VBOT during the production test. This guar-

antees that a Brown-out Reset will occur before VCC drops to a voltage where correct

operation of the microcontroller is no longer guaranteed. This test is performed using

BODLEVEL = 110 for ATmega162V, BODLEVEL = 101 and BODLEVEL = 100 for

ATmega162.

2. For ATmega162V. Otherwise reserved.

When the BOD is enabled and V

CC decreases to a value below the trigger level (VBOT- in Figure

25), the Brown-out Reset is immediately activated. When V

CC increases above the trigger level

BOT+ in Figure 25), the delay counter starts the MCU after the Time-out period tTOUT has

expired.

The BOD circuit will only detect a drop in V

CC if the voltage stays below the trigger level for lon-

ger than t

BOD given in Table 18.

Table 19. BODLEVEL Fuse Coding

BODLEVEL Fuses [2:0]

Min. VBOT

(1)

Typ. VBOT

Max. VBOT

Units

111

BOD Disabled

110(2)

1.7

1.8

2.0

101

2.5

2.7

2.9

100

4.1

4.3

4.5

011(2)

2.1

2.3

2.5

010

Reserved

001

000

Table 20. Brown-out Hysteresis

Symbol

Parameter

Min.

Typ.

Max.

Units

HYST

Brown-out Detector hysteresis

BOD

Min Pulse Width on Brown-out Reset

µs

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