ATMEGA6450-16AI(2004) データシートの表示（PDF） - Atmel Corporation

部品番号

コンポーネント説明

メーカー

ATMEGA6450-16AI
(Rev.:2004)

8-bit Microcontroller with In-System Programmable Flash

Atmel Corporation 

Watchdog Reset

2570A–AVR–09/04

ATmega325/3250/645/6450

teresis to ensure spike free Brown-out Detection. The hysteresis on the detection level

should be interpreted as VBOT+ = VBOT + VHYST/2 and VBOT- = VBOT - VHYST/2.

Table 17. BODLEVEL Fuse Coding(1)

BODLEVEL 2..0 Fuses

11

Min VBOT

Typ VBOT

Max VBOT

BOD Disabled

Units

10

1.8

01

2.7

V

00

4.3

Note:

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 VCC = 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.

The test is performed using BODLEVEL = 10 for ATmega325/3250/645/6450V and

BODLEVEL = 01 for ATmega325/3250/645/6450L.

Table 18. Brown-out Characteristics

Symbol Parameter

VHYST

tBOD

Brown-out Detector Hysteresis

Min Pulse Width on Brown-out Reset

Min Typ Max Units

50

mV

2

µs

When the BOD is enabled, and VCC decreases to a value below the trigger level (VBOT-

in Figure 19), the Brown-out Reset is immediately activated. When VCC increases above

the trigger level (VBOT+ in Figure 19), the delay counter starts the MCU after the Time-

out period tTOUT has expired.

The BOD circuit will only detect a drop in VCC if the voltage stays below the trigger level

for longer than tBOD given in Table 16.

Figure 19. Brown-out Reset During Operation

VCC

VBOT-

VBOT+

RESET

TIME-OUT

tTOUT

INTERNAL

RESET

When the Watchdog times out, it will generate a short reset pulse of one CK cycle dura-

tion. On the falling edge of this pulse, the delay timer starts counting the Time-out period

tTOUT. Refer to page 43 for details on operation of the Watchdog Timer.

41

Share Link: