ATMEGA162 datasheet(49/323 Pages) ATMEL

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ATmega162/V

2513F–AVR–12/03

Brown-out Detection

ATmega162 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

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

Notes:

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 = VBOT during the

production test. This guarantees 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

for ATmega162L, 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 (V

BOT+ in Figure 25), the delay counter starts the MCU after the Time-

out period t

TOUT has expired.

The BOD circuit will only detect a drop in V

CC if the voltage stays below the trigger level

for longer than t

BOD given in Table 18.

Table 19. BODLEVEL Fuse Coding

BODLEVEL Fuses [2:0]

Min. V

BOT

(1)

Typ. V

BOT

Max. V

BOT

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

tBOD

Min Pulse Width on Brown-out Reset

µs

ATMEGA162 Datasheet(PDF) 49 Page - ATMEL Corporation

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