ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 260

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

24.7
24.8
260
ADC Conversion Result
Temperature Measurement
Atmel ATmega48PA/88PA/168PA [Preliminary]
After the conversion is complete (ADIF is high), the conversion result can be found in the ADC
Result Registers (ADCL, ADCH).
For single ended conversion, the result is
where V
Table 24-3 on page 262
0x3FF represents the selected reference voltage minus one LSB.
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 converter can be used in single conversion mode to measure the voltage over the tem-
perature sensor.
The measured voltage has a linear relationship to the temperature as described in
The voltage sensitivity is approximately 1LSB/°C and the accuracy of the temperature mea-
surement is ±15°C using manufacturing calibration values (TS_GAIN, TS_OFFSET).
The values described in
the temperature sensor output varies from one chip to another.
Table 24-2.
ADC
Temperature/°C
=
IN
V
---------------------------- -
IN
is the voltage on the selected input pin and V
V
REF
Sensor Output Code versus Temperature (Typical Values)
1024
Table 24-2
and
Table 24-4 on page
0x010D
–40°C
are typical values. However, due to the process variation
263). 0x000 represents analog ground, and
REF
0x0160
+25°C
the selected voltage reference (see
+125°C
0x01E0
9223B–AVR–09/11
Table
24-2.