ATtiny26 Atmel Corporation, ATtiny26 Datasheet - Page 105

• Manufacturer Part Number: ATtiny26
• Manufacturer: Atmel Corporation

Specifications of ATtiny26

• Flash (kbytes): 2 Kbytes
• Pin Count: 20
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 16
• Ext Interrupts: 11
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 11
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 0.12
• Eeprom (bytes): 128
• Self Program Memory: NO
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• 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: 3
• Pwm Channels: 4
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

Scanning Multiple
Channels
ADC Noise
Canceling
Techniques
Offset
Compensation
Schemes
1477K–AVR–08/10
Since change of analog channel always is delayed until a conversion is finished, the Free Run-
ning mode can be used to scan multiple channels without interrupting the converter. Typically,
the ADC Conversion Complete interrupt will be used to perform the channel shift. However, the
user should take the following fact into consideration:
Digital circuitry inside and outside the ATtiny26(L) generates EMI which might affect the accu-
racy of analog measurements. If conversion accuracy is critical, the noise level can be reduced
by applying the following techniques:
1. The analog part of the ATtiny26(L) and all analog components in the application should
2. Keep analog signal paths as short as possible. Make sure analog tracks run over the
3. The AVCC pin on the ATtiny26(L) should be connected to the digital V
4. Use the ADC noise canceler function to reduce induced noise from the CPU.
5. If some pins are used as digital outputs, it is essential that these do not switch while a
The gain stage has a built-in offset cancellation circuitry that nulls the offset of differential mea-
surements as much as possible. The remaining offset in the analog path can be measured
directly by selecting the same channel for both differential inputs. This offset residue can be then
subtracted in software from the measurement results. Using this kind of software based offset
correction, offset on any channel can be reduced below one LSB.
The interrupt triggers once the result is ready to be read. In Free Running mode, the next
conversioin will start immediately when the interrupt triggers. If ADMUX is changed after the
interrupt triggers, the next conversion has already started, and the old setting is used.
have a separate analog ground plane on the PCB. This ground plane is connected to the
digital ground plane via a single point on the PCB.
analog ground plane, and keep them well away from high-speed switching digital tracks.
via an LC network as shown in Figure 57.
conversion is in progress in that port.
CC
supply voltage
105