TINY12 ATMEL [ATMEL Corporation], TINY12 Datasheet - Page 18

• Manufacturer Part Number: TINY12
• Description: 8-bit AVR Microcontroller with 1K Byte Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Power-on Reset for the
ATtiny11
18
ATtiny11/12
A Power-on Reset (POR) circuit ensures that the device is reset from power-on. As
shown in Figure 16, an internal timer is clocked from the watchdog timer. This timer pre-
vents the MCU from starting a certain period after V
Threshold Voltage – V
period – t
start-up time.The start-up times for the different clock options are shown in the following
table. The Watchdog Oscillator is used for timing the start-up time, and this oscillator is
voltage dependent as shown in the section “ATtiny11 Typical Characteristics” on page
60.
Table 7. Start-up Times for the ATtiny11 (V
If the built-in start-up delay is sufficient, RESET can be connected to V
an external pull-up resistor. By holding the RESET pin low for a period after V
been applied, the Power-on Reset period can be extended. Refer to Figure 19 for a tim-
ing example on this.
Selected Clock Option
External Crystal
External Ceramic Resonator
External Low-frequency Crystal
External RC Oscillator
Internal RC Oscillator
External Clock
TOUT
. The FSTRT fuse bit in the Flash can be programmed to give a shorter
POT
. See Figure 18. The total reset period is the Delay Time-out
FSTRT Unprogrammed
4.2 ms
4.2 ms
4.2 ms
67 ms
67 ms
CC
4.2 s
= 2.7V)
Start-up Time t
CC
has reached the Power-on
2 clocks from power-down
FSTRT Programmed
5 clocks from reset,
TOUT
4.2 ms
4.2 ms
67 µs
67 µs
CC
4.2 s
1006D–AVR–07/03
directly or via
CC
has