ATMEGA161 View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

ATMEGA161

8-bit Microcontroller with 16K Bytes In-System Programmable Flash

Atmel Corporation 

Figure 27. External Reset During Operation

ATmega161(L)

Brown-out Detection

ATmega161 has an on-chip brown-out detection (BOD) circuit for monitoring the VCC level during the operation. The BOD

circuit can be enabled/disabled by the fuse BODEN. When BODEN is enabled (BODEN programmed), and VCC decreases

to a value below the trigger level, the brown-out reset is immediately activated. When VCC increases above the trigger level,

the brown-out reset is deactivated after a delay. The delay is defined by the user in the same way as the delay of POR sig-

nal, in Table 4. The trigger level for the BOD can be selected by the fuse BODLEVEL to be 2.7V (BODLEVEL

unprogrammed), or 4.0V ((BODLEVEL programmed). The trigger level has a hysteresis of 50 mV to ensure spike free

brown-out detection.

The BOD circuit will only detect a drop in VCC if the voltage stays below the trigger level for longer than 9 µs for trigger level

4.0V, 21 µs for trigger level 2.7V (typical values).

Figure 28. Brown-out Reset During Operation

VCC

VBOT-

VBOT+

RESET

TIME-OUT

tTOUT

INTERNAL

RESET

Watchdog Reset

When the Watchdog times out, it will generate a short reset pulse of 1 XTAL cycle duration. On the falling edge of this

pulse, the delay timer starts counting the Time-out period tTOUT. Refer to Page page 52 for details on operation of the

Watchdog.

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