ATtiny25 Automotive Atmel Corporation, ATtiny25 Automotive Datasheet - Page 41

• Manufacturer Part Number: ATtiny25 Automotive
• Manufacturer: Atmel Corporation

Specifications of ATtiny25 Automotive

• Flash (kbytes): 2 Kbytes
• Pin Count: 8
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 4
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 6
• Ext Interrupts: 6
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 4
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 0.12
• Eeprom (bytes): 128
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 125
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 5
• Pwm Channels: 6
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

8.9
7598H–AVR–07/09
Watchdog Timer
ADC is used. To reduce power consumption in Power-down mode, the user can avoid the three
conditions above to ensure that the reference is turned off before entering Power-down mode.
Table 8-4.
The Watchdog Timer is clocked from an On-chip Oscillator which runs at 128 kHz. By controlling
the Watchdog Timer prescaler, the Watchdog Reset interval can be adjusted as shown in
8-7 on page
Watchdog Timer is also reset when it is disabled and when a Chip Reset occurs. Ten different
clock cycle periods can be selected to determine the reset period. If the reset period expires
without another Watchdog Reset, the ATtiny25/45/85 resets and executes from the Reset Vec-
tor. For timing details on the Watchdog Reset, refer to
The Wathdog Timer can also be configured to generate an interrupt instead of a reset. This can
be very helpful when using the Watchdog to wake-up from Power-down.
To prevent unintentional disabling of the Watchdog or unintentional change of time-out period,
two different safety levels are selected by the fuse WDTON as shown in Table 8-5. Refer to
“Timed Sequences for Changing the Configuration of the Watchdog Timer” on page 44
details.
Table 8-5.
Figure 8-7.
WDTON
Unprogrammed
Programmed
Symbol
V
t
I
BG
BG
BG
Parameter
Bandgap reference voltage
Bandgap reference start-up time
Bandgap reference current
consumption
43. The WDR – Watchdog Reset – instruction resets the Watchdog Timer. The
Internal Voltage Reference Characteristics
WDT Configuration as a Function of the Fuse Settings of WDTON
Watchdog Timer
Safety
Level
1
2
WATCHDOG
OSCILLATOR
RESET
128 kHz
WDP0
WDP1
WDP2
WDP3
WDE
WDT Initial
State
Disabled
Enabled
V
CC
How to Disable the
WDT
Timed sequence
Always enabled
V
V
Condition
T
T
T
= 1.1V / 2.7V,
CC
CC
A
A
A
= 25°C
= 25°C
= 25°C
= 2.7V,
= 2.7V,
Table 8-7 on page
MCU RESET
PRESCALER
WATCHDOG
ATtiny25/45/85
Min
1.0
43.
How to Change
Time-out
No limitations
Timed sequence
Typ
1.1
40
15
Max
1.2
70
Units
µA
Table
µs
V
for
41