ATDVK90CAN1 Atmel, ATDVK90CAN1 Datasheet - Page 31

• Manufacturer Part Number: ATDVK90CAN1
• Description: KIT DEV FOR AT90CAN128 MCU
• Manufacturer: Atmel

Specifications of ATDVK90CAN1

• Main Purpose: *
• Embedded: *
• Utilized Ic / Part: AT90CAN AVR Devices
• Primary Attributes: *
• Secondary Attributes: *
• Processor To Be Evaluated: AT90CAN
• Data Bus Width: 8 bit
• Interface Type: RS-232, SPI, TWI
• Core Architecture: AVR
• Core Sub-architecture: AVR UC3
• Kit Contents: Board, AT90CAN128 Sample Microcontroller, 9V Battery Power Cable, CD-ROM, Manuals
• Features: RS232, CAN, LIN, SPI & TWI Serial Interface
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

4381B–AVR–07/08
Using the DVK90CAN1
3.7.7
3-30
Temperature Sensor
The voltage input can be configured. It can be either the board supply voltage (VCC) or
an external input on T11 test pin. To improve the connection, close to T11, there is the
test pin T12 wrapped to GND.
Table 3-14 . Voltage Input Switch Configuration
The temperature sensor uses a thermistor, or temperature-sensitive resistor. This
thermistor have a negative temperature coefficient (NTC), meaning the resistance goes
up as temperature goes down. Of all passive temperature measurement sensors,
thermistors have the highest sensitivity (resistance change per degree of temperature
change). Thermistors do not have a linear temperature/resistance curve.
The voltage over the NTC can be found using the A/D converter. See the AT90CAN128
Datasheet for how to use the ADC. The thermistor value (R
following expression:
The NTC thermistor used in DVK90CAN1 has a resistance of 100 KΩ
and a beta-value of 4250 ±3%. By the use of the following equation, the temperature (T)
can be calculated:
The following cross table also can be used. It is based on the above equation.
Mode
VCC
R
T
Where:
Where:
=
(
R
H
⋅
V
T
ADC0
=
R
R
V
VCC = Board power supply
R
ß
R
T
-------------------------------
⎛
⎝
0
ADC0
T
H
T
0
ln
= 4250 ±3%
)
= 298 °K (273 °K + 25°K)
= 100 KΩ
= Thermistor value (Ω) at T temperature (°Kelvin)
= Thermistor value (Ω) at T temperature (°Kelvin)
= Second resistor of the bridge -100 KΩ
⁄
R
------ -
R
(
View
T
V
0
β
= Voltage value on ADC-0 input (V)
⎞
⎠
CC
+
----- -
T
β
–
0
±
V
5% at 25°C
ADC0
)
External
Input
Mode
(T11)
±
DVK90CAN1 Hardware User Guide
10% at 25°C
T
) is calculate with the
View
±
5% at 25°C (T
T11 = VIN
T12 = GND
0
)