MCP9700 Specifications
Table Of Contents
- 1.0 Electrical Characteristics
- 2.0 Typical Performance Curves
- FIGURE 2-1: Accuracy vs. Ambient Temperature (MCP9700A/9701A).
- FIGURE 2-2: Accuracy vs. Ambient Temperature, with VDD.
- FIGURE 2-3: Supply Current vs. Temperature.
- FIGURE 2-4: Accuracy vs. Ambient Temperature (MCP9700/9701).
- FIGURE 2-5: Changes in Accuracy vs. Ambient Temperature (Due to Load).
- FIGURE 2-6: Load Regulation vs. Ambient Temperature.
- FIGURE 2-7: Output Voltage at 0˚C (MCP9700/9700A).
- FIGURE 2-8: Occurrences vs. Temperature Coefficient (MCP9700/9700A).
- FIGURE 2-9: Power Supply Rejection (D˚C/DVDD) vs. Ambient Temperature.
- FIGURE 2-10: Output Voltage at 0˚C (MCP9701/9701A).
- FIGURE 2-11: Occurrences vs. Temperature Coefficient (MCP9701/9701A).
- FIGURE 2-12: Power Supply Rejection (D˚C/DVDD) vs. Temperature.
- FIGURE 2-13: Output Voltage vs. Power Supply.
- FIGURE 2-14: Output vs. Settling Time to step VDD.
- FIGURE 2-15: Thermal Response (Air to Fluid Bath).
- FIGURE 2-16: Output Voltage vs. Ambient Temperature.
- FIGURE 2-17: Output vs. Settling Time to Ramp VDD.
- FIGURE 2-18: Output Impedance vs. Frequency.
- 3.0 Pin Descriptions
- 4.0 Applications Information
- 5.0 Packaging Information
MCP9700/9700A and MCP9701/9701A
DS21942D-page 8 © 2007 Microchip Technology Inc.
4.0 APPLICATIONS INFORMATION
The Linear Active Thermistor™ IC uses an internal
diode to measure temperature. The diode electrical
characteristics have a temperature coefficient that
provides a change in voltage based on the relative
ambient temperature from -40°C to 125°C. The change
in voltage is scaled to a temperature coefficient of
10.0 mV/°C (typical) for the MCP9700/9700A and
19.5 mV/°C (typical) for the MCP9701/9701A. The out-
put voltage at 0°C is also scaled to 500 mV (typical)
and 400 mV (typical) for the MCP9700/9700A and
MCP9701/9701A, respectively. This linear scale is
described in the first-order transfer function shown in
Equation 4-1.
EQUATION 4-1: SENSOR TRANSFER
FUNCTION
FIGURE 4-1: Typical Application Circuit.
4.1 Improving Accuracy
The MCP9700/9700A and MCP9701/9701A accuracy
can be improved by performing a system calibration at
a specific temperature. For example, calibrating the
system at +25°C ambient improves the measurement
accuracy to a ±0.5°C (typical) from 0°C to +70°C, as
shown in Figure 4-2. Therefore, when measuring
relative temperature change, this family measures
temperature with higher accuracy.
FIGURE 4-2: Relative Accuracy to +25°C
vs. Temperature.
The change in accuracy from the calibration
temperature is due to the output non-linearity from the
first-order equation, as specified in Equation 4-2. The
accuracy can be further improved by compensating for
the output non-linearity.
For higher accuracy using a sensor compensation
technique, refer to AN1001 “IC Temperature Sensor
Accuracy Compensation with a PICmicro
®
Microcontroller” (DS01001). The application note
shows that if the MCP9700 is compensated in addition
to room temperature calibration, the sensor accuracy
can be improved to ±0.5°C (typical) accuracy over the
operating temperature
(Figure 4-3).
FIGURE 4-3: MCP9700/9700A Calibrated
Sensor Accuracy.
The compensation technique provides a linear
temperature reading. A firmware look-up table can be
generated to compensate for the sensor error.
V
OUT
T
C
T
A
V
0°C
+•=
Where:
T
A
= Ambient Temperature
V
OUT
= Sensor Output Voltage
V
0°C
= Sensor Output Voltage at 0°C
T
C
= Temperature Coefficient
V
DD
V
SS
GND
ANI
V
DD
V
SS
V
OUT
MCP9700
PICmicro®
MCU
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
-50-250 255075100125
T
A
(°C)
Accuracy (°C)
V
DD
= 3.3V
10 Samples
-4.0
-2.0
0.0
2.0
4.0
6.0
-50 -25 0 25 50 75 100 125
Temperature (°C)
Accuracy (°C)
+
V
Average
-
V
Spec. Limits
100 Samples