ATTINY12(2003) 查看數據表（PDF） - Atmel Corporation

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ATTINY12
(Rev.:2003)

8-bit Microcontroller with 1K Byte Flash

Atmel Corporation 

Reset Sources

ATtiny11/12

The ATtiny11/12 provides three or four sources of reset:

• Power-on Reset. The MCU is reset when the supply voltage is below the power-on

reset threshold (VPOT).

• External Reset. The MCU is reset when a low level is present on the RESET pin for

more than 50 ns.

• Watchdog Reset. The MCU is reset when the Watchdog timer period expires and

the Watchdog is enabled.

• Brown-out Reset. The MCU is reset when the supply voltage VCC falls below a

certain voltage (ATtiny12 only).

During reset, all I/O registers are then set to their initial values, and the program starts

execution from address $000. The instruction placed in address $000 must be an RJMP

– relative jump – instruction to the reset handling routine. If the program never enables

an interrupt source, the interrupt vectors are not used, and regular program code can be

placed at these locations. The circuit diagram in Figure 16 shows the reset logic for the

ATtiny11. Figure 17 shows the reset logic for the ATtiny12. Table 6 defines the electrical

parameters of the reset circuitry for ATtiny11. Table 8 shows the parameters of the reset

circuitry for ATtiny12.

Figure 16. Reset Logic for the ATtiny11

VCC

Power-on Reset

Circuit

POR

RESET

Reset Circuit

Watchdog

Timer

On-chip

RC Oscillator

20-stage Ripple Counter

Q3 Q9

Q13

Q19

SQ

RQ

Table 6. Reset Characteristics for the ATtiny11

Symbol Parameter

Min Typ Max Units

Power-on Reset Threshold Voltage (rising)

1.0

1.4

1.8

V

VPOT(1)

Power-on Reset Threshold Voltage (falling)

0.4

0.6

0.8

V

VRST

Note:

RESET Pin Threshold Voltage

0.6 VCC

V

1. The Power-on Reset will not work unless the supply voltage has been below VPOT

(falling).

17

1006D–AVR–07/03

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