- •Features
- •1. Pin Configurations
- •1.1 Disclaimer
- •2. Overview
- •2.1 Block Diagram
- •2.2 Pin Descriptions
- •2.2.3 AVCC
- •2.2.4 AGND
- •2.2.5 Port A (PA7..PA0)
- •2.2.6 Port B (PB7..PB0)
- •2.2.7 RESET
- •3. Resources
- •4. About Code Examples
- •5. AVR CPU Core
- •5.1 Overview
- •5.3 Status Register
- •5.4 General Purpose Register File
- •5.5 Stack Pointer
- •5.6 Instruction Execution Timing
- •5.7 Reset and Interrupt Handling
- •5.7.1 Interrupt Response Time
- •6. AVR Memories
- •6.2 SRAM Data Memory
- •6.2.1 Data Memory Access Times
- •6.3 EEPROM Data Memory
- •6.3.1 EEPROM Read/Write Access
- •6.3.2 Atomic Byte Programming
- •6.3.3 Split Byte Programming
- •6.3.4 Erase
- •6.3.5 Write
- •6.3.6 Preventing EEPROM Corruption
- •6.4 I/O Memory
- •6.4.1 General Purpose I/O Registers
- •6.5 Register Description
- •7. System Clock and Clock Options
- •7.1 Clock Systems and their Distribution
- •7.2 Clock Sources
- •7.3 Default Clock Source
- •7.4 External Clock
- •7.6 Calibrated Internal RC Oscillator
- •7.7 128 kHz Internal Oscillator
- •7.9 Crystal Oscillator
- •7.10 Clock Output Buffer
- •7.11 System Clock Prescaler
- •7.11.1 Switching Time
- •7.12 Register Description
- •8. Power Management and Sleep Modes
- •8.1 Sleep Modes
- •8.2 Idle Mode
- •8.3 ADC Noise Reduction Mode
- •8.5 Standby Mode
- •8.6 Power Reduction Register
- •8.7 Minimizing Power Consumption
- •8.7.1 Analog to Digital Converter
- •8.7.2 Analog Comparator
- •8.7.4 Internal Voltage Reference
- •8.7.5 Watchdog Timer
- •8.7.6 Port Pins
- •8.8 Register Description
- •9. System Control and Reset
- •9.0.1 Resetting the AVR
- •9.0.2 Reset Sources
- •9.0.4 External Reset
- •9.0.6 Watchdog Reset
- •9.1 Internal Voltage Reference
- •9.2 Watchdog Timer
- •9.3 Timed Sequences for Changing the Configuration of the Watchdog Timer
- •9.3.1 Safety Level 1
- •9.3.2 Safety Level 2
- •9.4 Register Description
- •10. Interrupts
- •10.1 Interrupt Vectors in ATtiny261/461/861
- •11. External Interrupts
- •11.1 Register Description
- •12. I/O Ports
- •12.1 Overview
- •12.2 Ports as General Digital I/O
- •12.2.1 Configuring the Pin
- •12.2.2 Toggling the Pin
- •12.2.3 Switching Between Input and Output
- •12.2.4 Reading the Pin Value
- •12.2.5 Digital Input Enable and Sleep Modes
- •12.2.6 Unconnected Pins
- •12.3 Alternate Port Functions
- •12.3.1 Alternate Functions of Port B
- •12.3.2 Alternate Functions of Port A
- •12.4 Register Description
- •13. Timer/Counter0 Prescaler
- •13.0.1 Prescaler Reset
- •13.0.2 External Clock Source
- •13.1 Register Description
- •14. Timer/Counter0
- •14.1 Features
- •14.2 Overview
- •14.2.1 Registers
- •14.2.2 Definitions
- •14.3 Timer/Counter Clock Sources
- •14.4 Counter Unit
- •14.5 Modes of Operation
- •14.5.1 Normal 8-bit Mode
- •14.6 Input Capture Unit
- •14.6.1 Input Capture Trigger Source
- •14.6.2 Noise Canceler
- •14.6.3 Using the Input Capture Unit
- •14.7 Output Compare Unit
- •14.7.1 Compare Match Blocking by TCNT0 Write
- •14.7.2 Using the Output Compare Unit
- •14.8 Timer/Counter Timing Diagrams
- •14.9.1 Reusing the temporary high byte register
- •14.10 Register Description
- •15. Timer/Counter1 Prescaler
- •15.0.1 Prescaler Reset
- •15.0.2 Prescaler Initialization for Asynchronous Mode
- •15.1 Register Description
- •16. Timer/Counter1
- •16.1 Features
- •16.2 Overview
- •16.2.1 Speed
- •16.2.2 Accuracy
- •16.2.3 Registers
- •16.2.4 Synchronization
- •16.2.5 Definitions
- •16.3 Counter Unit
- •16.3.1 Counter Initialization for Asynchronous Mode
- •16.4 Output Compare Unit
- •16.4.1 Force Output Compare
- •16.4.2 Compare Match Blocking by TCNT1 Write
- •16.4.3 Using the Output Compare Unit
- •16.5 Dead Time Generator
- •16.6 Compare Match Output Unit
- •16.6.1 Compare Output Mode and Waveform Generation
- •16.7 Modes of Operation
- •16.7.1 Normal Mode
- •16.7.3 Phase and Frequency Correct PWM Mode
- •16.7.4 PWM6 Mode
- •16.8 Timer/Counter Timing Diagrams
- •16.9 Fault Protection Unit
- •16.9.1 Fault Protection Trigger Source
- •16.9.2 Noise Canceler
- •16.10 Accessing 10-Bit Registers
- •16.10.1 Reusing the temporary high byte register
- •16.11 Register Description
- •17.1 Features
- •17.2 Overview
- •17.3 Functional Descriptions
- •17.3.2 SPI Master Operation Example
- •17.3.3 SPI Slave Operation Example
- •17.3.5 Start Condition Detector
- •17.4 Alternative USI Usage
- •17.4.4 Edge Triggered External Interrupt
- •17.4.5 Software Interrupt
- •17.5 Register Descriptions
- •18.1 Register Description
- •18.2 Analog Comparator Multiplexed Input
- •19.1 Features
- •19.2 Overview
- •19.3 Operation
- •19.4 Starting a Conversion
- •19.5 Prescaling and Conversion Timing
- •19.6 Changing Channel or Reference Selection
- •19.6.1 ADC Input Channels
- •19.6.2 ADC Voltage Reference
- •19.7 ADC Noise Canceler
- •19.7.1 Analog Input Circuitry
- •19.7.2 Analog Noise Canceling Techniques
- •19.7.3 ADC Accuracy Definitions
- •19.8 ADC Conversion Result
- •19.8.1 Single Ended Conversion
- •19.8.2 Unipolar Differential Conversion
- •19.8.3 Bipolar Differential Conversion
- •19.9 Temperature Measurement
- •19.10 Register Descriptin
- •19.10.3.1 ADLAR = 0
- •19.10.3.2 ADLAR = 1
- •20. debugWIRE On-chip Debug System
- •20.1 Features
- •20.2 Overview
- •20.3 Physical Interface
- •20.4 Software Break Points
- •20.5 Limitations of debugWIRE
- •20.6 Register Description
- •21. Self-Programming the Flash
- •21.0.1 Performing Page Erase by SPM
- •21.0.2 Filling the Temporary Buffer (Page Loading)
- •21.0.3 Performing a Page Write
- •21.1.1 EEPROM Write Prevents Writing to SPMCSR
- •21.1.2 Reading the Fuse and Lock Bits from Software
- •21.1.3 Preventing Flash Corruption
- •21.1.4 Programming Time for Flash when Using SPM
- •21.2 Register Description
- •22. Memory Programming
- •22.1 Program And Data Memory Lock Bits
- •22.2 Fuse Bytes
- •22.2.1 Latching of Fuses
- •22.3 Signature Bytes
- •22.4 Calibration Byte
- •22.5 Page Size
- •22.6 Parallel Programming Parameters, Pin Mapping, and Commands
- •22.6.1 Signal Names
- •22.7 Parallel Programming
- •22.7.1 Enter Programming Mode
- •22.7.2 Considerations for Efficient Programming
- •22.7.3 Chip Erase
- •22.7.4 Programming the Flash
- •22.7.5 Programming the EEPROM
- •22.7.6 Reading the Flash
- •22.7.7 Reading the EEPROM
- •22.7.8 Programming the Fuse Low Bits
- •22.7.9 Programming the Fuse High Bits
- •22.7.10 Programming the Extended Fuse Bits
- •22.7.11 Programming the Lock Bits
- •22.7.12 Reading the Fuse and Lock Bits
- •22.7.13 Reading the Signature Bytes
- •22.7.14 Reading the Calibration Byte
- •22.8 Serial Downloading
- •22.8.1 Serial Programming Algorithm
- •22.8.2 Serial Programming Instruction set
- •23. Electrical Characteristics
- •23.1 Absolute Maximum Ratings*
- •23.2 DC Characteristics
- •23.3 Speed Grades
- •23.4 Clock Characteristics
- •23.4.1 Calibrated Internal RC Oscillator Accuracy
- •23.4.2 External Clock Drive Waveforms
- •23.4.3 External Clock Drive
- •23.5 System and Reset Characteristics
- •23.7 Parallel Programming Characteristics
- •23.8 Serial Programming Characteristics
- •24. Typical Characteristics
- •24.1 Active Supply Current
- •24.2 Idle Supply Current
- •24.3 Supply Current of I/O modules
- •Example
- •24.6 Pin Driver Strength
- •24.7 Pin Threshold and Hysteresis
- •24.8 BOD Threshold and Analog Comparator Offset
- •24.9 Internal Oscillator Speed
- •24.10 Current Consumption of Peripheral Units
- •24.11 Current Consumption in Reset and Reset Pulsewidth
- •25. Register Summary
- •26. Instruction Set Summary
- •27. Ordering Information
- •27.1 ATtiny261
- •27.2 ATtiny461
- •27.3 ATtiny861
- •28. Packaging Information
- •29. Errata
- •29.1 Errata ATtiny261
- •29.2 Errata ATtiny461
- •29.3 Errata ATtiny861
- •30. Datasheet Revision History
- •Table of Contents
Figure 24-10. Idle Supply Current vs. VCC (Internal RC Oscillator, 128 kHz)
IDLE SUPPLY CURRENT vs. VCC
INTERNAL RC OSCILLATOR, 128 kHz
ICC (mA)
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0,18 |
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0,16 |
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0,14 |
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0,12 |
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0,1 |
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25 |
˚C |
0,08 |
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-40 |
˚C |
0,06 |
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0,04 |
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0,02 |
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1,5 |
2 |
2,5 |
3 |
3,5 |
4 |
4,5 |
5 |
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VCC (V)
24.3Supply Current of I/O modules
The tables and formulas below can be used to calculate the additional current consumption for the different I/O modules in Active and Idle mode. The enabling or disabling of the I/O modules are controlled by the Power Reduction Register. See ”PRR – Power Reduction Register” on page 37 for details.
Table 24-1. |
Additional Current Consumption for the different I/O modules (absolute values) |
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PRR bit |
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Typical numbers |
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VCC = 2V, F = 1MHz |
VCC = 3V, F = 4MHz |
VCC = 5V, F = 8MHz |
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PRTIM1 |
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65 uA |
423 uA |
1787 uA |
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PRTIM0 |
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7 uA |
39 uA |
165 uA |
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PRUSI |
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5 uA |
25 uA |
457 uA |
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PRADC |
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18 uA |
111 uA |
102 uA |
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Table 24-2. |
Additional Current Consumption (percentage) in Active and Idle mode |
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Additional Current consumption |
Additional Current consumption |
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compared to Active with external |
compared to Idle with external |
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clock (see Figure 24-1 on page |
clock (see Figure 24-6 on page |
PRR bit |
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195 and Figure 24-2 on page 196) |
198 and Figure 24-7 on page 198) |
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PRTIM1 |
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26.9 % |
103.7 % |
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PRTIM0 |
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2.6 % |
10.0 % |
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PRUSI |
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1.7 % |
6.5 % |
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PRADC |
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7.1 % |
27.3 % |
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It is possible to calculate the typical current consumption based on the numbers from Table 24-1 for other VCC and frequency settings than listed in Table 24-2.
200 ATtiny261/461/861 
2588B–AVR–11/06
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ATtiny261/461/861 |
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Example |
Calculate the expected current consumption in idle mode with TIMER0, ADC, and USI enabled |
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at VCC = 2.0V and F = 1MHz. From Table 24-2, third column, we see that we need to add 10% |
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for the TIMER0, 27.3 % for the ADC, and 6.5 % for the USI module. Reading from Figure 24-6 |
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on page 198, we find that the idle current consumption is ~0,085 mA at VCC = 2.0V and F=1MHz. |
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The total current consumption in idle mode with TIMER0, ADC, and USI enabled, gives: |
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ICCtotal ≈ 0,085mA • (1 + 0,10 + 0,273 + 0,065) ≈ 0,122mA |
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24.4Power-down Supply Current
Figure 24-11. Power-down Supply Current vs. VCC (Watchdog Timer Disabled)
POWER-DOWN SUPPLY CURRENT vs. VCC
WATCHDOG TIMER DISABLED
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1,6 |
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1,4 |
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85 ˚C |
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1,2 |
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1 |
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0,8 |
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-40 ˚C |
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0,6 |
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25 ˚C |
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0,4 |
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0,2 |
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1,5 |
2 |
2,5 |
3 |
3,5 |
4 |
4,5 |
5 |
5,5 |
VCC (V)
Figure 24-12. Power-down Supply Current vs. VCC (Watchdog Timer Enabled)
ICC (uA)
POWER-DOWN SUPPLY CURRENT vs. VCC
WATCHDOG TIMER ENABLED
10
-40 ˚C
9
85 ˚C
8 |
25 ˚C |
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4
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2
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0
1,5 |
2 |
2,5 |
3 |
3,5 |
4 |
4,5 |
5 |
5,5 |
VCC (V)
201
2588B–AVR–11/06
24.5Pin Pull-up
Figure 24-13. I/O Pin pull-up Resistor Current vs. Input Voltage (VCC = 1.8V)
I/O PIN PULL-UP RESISTOR CURRENT vs. INPUT VOLTAGE
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60 |
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40 |
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30 |
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25 ˚C |
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85 ˚C |
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-40 ˚C |
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0,2 |
0,4 |
0,6 |
0,8 |
1 |
1,2 |
1,4 |
1,6 |
1,8 |
2 |
VOP (V)
Figure 24-14. I/O Pin pull-up Resistor Current vs. Input Voltage (VCC = 2.7V)
I/O PIN PULL-UP RESISTOR CURRENT vs. INPUT VOLTAGE
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VCC = 2.7V |
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80 |
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70 |
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60 |
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50 |
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OP |
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20 |
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25 ˚C |
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10 |
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85 ˚C |
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-40 ˚C |
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0 |
0,5 |
1 |
1,5 |
2 |
2,5 |
3 |
VOP (V)
202 ATtiny261/461/861 
2588B–AVR–11/06
ATtiny261/461/861
Figure 24-15. I/O Pin pull-up Resistor Current vs. Input Voltage (VCC = 5V)
I/O PIN PULL-UP RESISTOR CURRENT vs. INPUT VOLTAGE
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VCC = 5V |
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160 |
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140 |
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120 |
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100 |
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25 ˚C |
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20 |
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85 ˚C |
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-40 ˚C |
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1 |
2 |
3 |
4 |
5 |
6 |
VOP (V)
Figure 24-16. Reset Pull-up Resistor Current vs. Reset Pin Voltage (VCC = 1.8V)
IRESET(uA)
RESET PULL-UP RESISTOR CURRENT vs. RESET PIN VOLTAGE
VCC = 1.8V
40
35
30
25
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25 |
˚C |
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-40 |
˚C |
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85 |
˚C |
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0,2 |
0,4 |
0,6 |
0,8 |
1 |
1,2 |
1,4 |
1,6 |
1,8 |
2 |
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VRESET(V)
203
2588B–AVR–11/06
Figure 24-17. Reset Pull-up Resistor Current vs. Reset Pin Voltage (VCC = 2.7V)
RESET PULL-UP RESISTOR CURRENT vs. RESET PIN VOLTAGE
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RESET |
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25 ˚C |
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-40 ˚C |
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85 ˚C |
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0,5 |
1 |
1,5 |
2 |
2,5 |
3 |
VRESET(V)
Figure 24-18. Reset Pull-up Resistor Current vs. Reset Pin Voltage (VCC = 5V)
RESET PULL-UP RESISTOR CURRENT vs. RESET PIN VOLTAGE
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120 |
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100 |
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80 |
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60 |
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RESET |
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25 ˚C |
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-40 ˚C |
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0 |
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85 ˚C |
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0 |
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VRESET(V)
204 ATtiny261/461/861 
2588B–AVR–11/06