ATtiny461 Automotive Atmel Corporation, ATtiny461 Automotive Datasheet - Page 155

• Manufacturer Part Number: ATtiny461 Automotive
• Manufacturer: Atmel Corporation

Specifications of ATtiny461 Automotive

• Flash (kbytes): 4 Kbytes
• Pin Count: 20
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 8
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 16
• Ext Interrupts: 16
• 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: Yes
• Crypto Engine: No
• Sram (kbytes): 0.25
• Eeprom (bytes): 256
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 150
• 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: 6
• Input Capture Channels: 1
• Pwm Channels: 6
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

19.8.3
19.9
7753F–AVR–01/11
Temperature Measurement
Bipolar Differential Conversion
As default the ADC converter operates in the unipolar input mode, but the bipolar input mode
can be selected by writing the BIN bit in the ADCSRB to one. In the bipolar input mode two-sided
voltage differences are allowed and thus the voltage on the negative input pin can also be larger
than the voltage on the positive input pin. If differential channels and a bipolar input mode are
used, the result is
where V
and V
0x200 (-512d) through 0x000 (+0d) to 0x1FF (+511d). The GAIN is either 1x, 8x, 20x or 32x.
However, if the signal is not bipolar by nature (9 bits + sign as the 10th bit), this scheme loses
one bit of the converter dynamic range. Then, if the user wants to perform the conversion with
the maximum dynamic range, the user can perform a quick polarity check of the result and use
the unipolar differential conversion with selectable differential input pair. When the polarity check
is performed, it is sufficient to read the MSB of the result (ADC9 in ADCH). If the bit is one, the
result is negative, and if this bit is zero, the result is positive.
The temperature measurement is based on an on-chip temperature sensor that is coupled to a
single ended ADC input. MUX[4..0] bits in ADMUX register enables the temperature sensor. The
internal 1.1V voltage reference must also be selected for the ADC voltage reference source in
the temperature sensor measurement. When the temperature sensor is enabled, the ADC con-
verter can be used in single conversion mode to measure the voltage over the temperature
sensor.
The measured voltage has a linear relationship to the temperature as described in
The voltage sensitivity is approximately 1LSB/
ment is ±
The values described in
temperature sensor output varies from one chip to another.
Table 19-2.
Temperature / °C
REF
POS
10°
the selected voltage reference. The result is presented in two’s complement form, from
C using manufacturing calibration values (TS_GAIN, TS_OFFSET).
is the voltage on the positive input pin, V
Temperature vs. Sensor Output Voltage (Typical Case): Example ADC Values
Table 19-2
ADC
0x00F6
-40°C
=
ATtiny261/ATtiny461/ATtiny861
are typical values. However, due to the process variation the
-------------------------------------------------------
V
POS
–
V
V
REF
NEG
°
C and the accuracy of the temperature measure-
512
NEG
0x0144
+25 °C
the voltage on the negative input pin,
GAIN
+125 °C
0c01B8
Table
19-2.
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