ATTINY85-15ST1 Atmel, ATTINY85-15ST1 Datasheet - Page 41

• Manufacturer Part Number: ATTINY85-15ST1
• Description: MCU AVR 8K FLASH 15MHZ 8-SOIC
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY85-15ST1

• Package / Case: 8-SOIC (3.9mm Width)
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 105°C
• Speed: 16MHz
• Number Of I /o: 6
• Eeprom Size: 512 x 8
• Core Processor: AVR
• Program Memory Type: FLASH
• Ram Size: 512 x 8
• Program Memory Size: 8KB (8K x 8)
• Data Converters: A/D 4x10b
• Oscillator Type: Internal
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Connectivity: USI
• Core Size: 8-Bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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