Datasheet
Table Of Contents
- Thermocouple EMF to Temperature Converter, ±1.5 °C Maximum Accuracy
- 1.0 Electrical Characteristics
- 2.0 Typical Performance Curves
- FIGURE 2-1: Typical Temperature Accuracy from NIST ITS-90 Database, Type K.
- FIGURE 2-2: Typical Temperature Accuracy from NIST ITS-90 Database, Type J.
- FIGURE 2-3: Typical Temperature Accuracy from NIST ITS-90 Database, Type N.
- FIGURE 2-4: Temperature Sensitivity with 18-Bit Resolution, Type K.
- FIGURE 2-5: Temperature Sensitivity with 18-Bit Resolution, Type J.
- FIGURE 2-6: Temperature Sensitivity with 18-Bit Resolution, Type N.
- FIGURE 2-7: Typical Temperature Accuracy from NIST ITS-90 Database, Type S.
- FIGURE 2-8: Typical Temperature Accuracy from NIST ITS-90 Database, Type R.
- FIGURE 2-9: Typical Temperature Accuracy from NIST ITS-90 Database, Type E.
- FIGURE 2-10: Temperature Sensitivity with 18-Bit Resolution, Type S.
- FIGURE 2-11: Temperature Sensitivity with 18-Bit Resolution, Type R.
- FIGURE 2-12: Temperature Sensitivity with 18-Bit Resolution, Type E.
- FIGURE 2-13: Typical Temperature Accuracy from NIST ITS-90 Database, Type T.
- FIGURE 2-14: Typical Temperature Accuracy from NIST ITS-90 Database, Type B.
- FIGURE 2-15: Input Offset Error Voltage (VIN+, VIN-).
- FIGURE 2-16: Temperature Sensitivity with 18-Bit Resolution, Type T.
- FIGURE 2-17: Temperature Sensitivity with 18-Bit Resolution, Type B.
- FIGURE 2-18: Full-Scale Gain Error.
- FIGURE 2-19: Input Noise, % of Full-Scale.
- FIGURE 2-20: Cold-Junction Sensor Temperature Accuracy.
- FIGURE 2-21: SDA and Alert Outputs, VOL across VDD.
- FIGURE 2-22: Integral Nonlinearity across VDD.
- FIGURE 2-23: Cold-Junction Sensor Temperature Accuracy Distribution.
- FIGURE 2-24: Alert Outputs, VOH across VDD.
- FIGURE 2-25: I2C Inactive IDD across VDD.
- FIGURE 2-26: I2C Active IDD across VDD.
- FIGURE 2-27: Shutdown Current, ISHDN across VDD.
- FIGURE 2-28: SDA, SCL and ADDR Input Pins Leakage Current, ILEAK across VDD.
- FIGURE 2-29: I2C Interface Clock Stretch Duration, tSTRETCH across VDD.
- FIGURE 2-30: Temperature Calculation Duration, tCALC change across VDD.
- 3.0 Pin Description
- 4.0 Serial Communication
- 4.1 2-Wire Standard Mode I2C Protocol-Compatible Interface
- TABLE 4-1: MCP9600 Serial Bus protocol descriptions
- FIGURE 4-1: Device Addressing.
- FIGURE 4-2: Clock Stretching.
- FIGURE 4-3: Timing Diagram to Set a Register Pointer and Read a Two Byte Data.
- FIGURE 4-4: Timing Diagram to Set a Register Pointer and Read a Two Byte Data.
- FIGURE 4-5: Timing Diagram to Set a Register Pointer and Read a Two Byte Data.
- FIGURE 4-6: Timing Diagram to Sequential Read all Registers Starting from TH Register.
- 5.0 Functional Description
- FIGURE 5-1: Functional Block Diagram.
- Register 5-1: REGISTER POINTER
- TABLE 5-1: Summary of Registers and Bit Assignments
- 5.1 Thermocouple Temperature Sensor Registers
- EQUATION 5-1: Temperature Conversion
- FIGURE 5-2: Thermocouple Register’s Block Diagram.
- Register 5-2: Thermocouple Temperature Register (Read only)
- EQUATION 5-2: Temperature Conversion
- FIGURE 5-3: Thermocouple Hot-Junction Register – TΔ Block Diagram.
- Register 5-3: HOT-Junction Temperature register (READ only)
- EQUATION 5-3: Temperature Conversion
- TABLE 5-2: Resolution vs. Conversion Time
- FIGURE 5-4: Thermocouple Cold-Junction Register – TC Block Diagram.
- Register 5-4: COLD-JUNCTION TEMPERATURE REGISTER
- TABLE 5-3: ADC Resolution
- FIGURE 5-5: Delta Sigma Analog to Digital Converter, ADC Core – Block Diagram.
- Register 5-5: SAMPLE: 24-bit Register
- 5.2 Sensor Status and Configuration Registers
- 5.3 Temperature Alert Registers
- TABLE 5-4: Alert Limit Registers
- Register 5-9: Alert Limits 1, 2, 3 and 4 registers
- FIGURE 5-8: Alert Limits Set to Detect TH and TC.
- FIGURE 5-9: Alert Limits Boundary Conditions and Output Characteristics when Set to Detect TH.
- TABLE 5-5: Alert Hysteresis Registers
- Register 5-10: Alert 1, 2, 3 and 4 Hysteresis Register
- FIGURE 5-10: Graphical Description of Alert Output Hysteresis Direction.
- TABLE 5-6: Alert CONFIG. Registers
- Register 5-11: Alert 1, 2, 3 and 4 Configuration Register
- Register 5-12: Device ID and revision ID register
- 6.0 Application Information
- 6.1 Layout Considerations
- 6.2 Thermal Considerations
- 6.3 Device Features
- TABLE 6-2: Recommended Resistor Values for I2C Addressing
- FIGURE 6-4: I2C Address Selection Implementation.
- FIGURE 6-5: Thermocouple Input Stage.
- FIGURE 6-6: Adding Open-Circuit Detection Resistors.
- FIGURE 6-7: Adding a Low-Pass Filter.
- FIGURE 6-8: Adding Open-Circuit Detection Resistors with an Input Low-Pass Filter.
- FIGURE 6-9: Adding Ferrite Beads.
- 7.0 Packaging Information
- Appendix A: Revision History
- Product Identification System
- Trademarks
- Worldwide Sales and Service
2015-2016 Microchip Technology Inc. DS20005426B-page 39
MCP9600
6.3 Device Features
6.3.1 I
2
C ADDRESSING
The MCP9600 supports up to eight devices on the I
2
C
bus. Applications such as large thermal management
racks with several thermocouple sensor interfaces are
able to monitor various temperature zones with minimal
pin-count microcontrollers. This reduces the total solu-
tion cost, while providing a highly accurate thermal
management solution using the MCP9600.
FIGURE 6-4: I
2
C Address Selection
Implementation.
6.3.2 INPUT IMPEDANCE
The MCP9600 uses a switched-capacitor amplifier
input stage to gain the input signal to a maximum
resolution of 2 µV/LSb at 18-bit ADC setting. An
internal input capacitor is used for charge storage. The
differential input impedance Z
IN_DF
is dominated by the
sampling capacitor and the switched-capacitor
amplifier sampling frequency. During sampling period,
the charging and discharging of the sampling capacitor
creates dynamic input currents at the input pins.
Adding a 10-100 nF capacitor between the inputs can
improve stability.
Since the sampling capacitor is only switching to the
input pins during a conversion process, the input
impedance is only valid during conversion periods.
During low-power or Shutdown mode, the input ampli-
fier stage is disabled, therefore the input impedance is
Z
IN_CM
, which is due to the leakage current from ESD
protection diodes, as shown in Figure 6-5.
FIGURE 6-5: Thermocouple Input Stage.
6.3.3 OPEN AND SHORT DETECTION
CIRCUITS
External circuits can be added to detect the
thermocouple status as open (physically disconnected)
or as short (thermocouple wire in contact with the
system ground or V
DD
). If a passive circuit is added to
the input stage, then the circuit loading effect to the
MCP9600 ADC inputs must be considered. System
calibration is also required to ensure proper accuracy.
In addition, external loads can degrade the device
performance, such as input offset, gain, and Integral
Nonlinearity (INL) errors. If a low impedance active
circuit is added, then both offset and gain errors must
be calibrated.
6.3.3.1 Open-Circuit Detection Technique
For open circuit detection, the Input Range Flag bit,
bit 4 of the Status Register (Register 5-6), can be used
to detect open-circuit conditions. This would require a
few external resistors as shown in Figure 6-6. The
passive circuit does not affect the MCP9600 accuracy
(The recommended value for R
B
set to 10 k. When
the Thermocouple is connected, the input
common-mode voltage is 0.5*V
DD
. And when the
Thermocouple is disconnected, the voltage at V
IN+
MCP9600
PIC
®
I
2
C
Alert
4
GND
Types K, J, T,
N, E, B, S, R
V
DD
Alert
4
GND
Types K, J, T,
N, E, B, S, R
V
DD
MCP9600
R
7A
R
7B
R
2A
R
2B
Up to eight
MCP9600 on
I
2
C bus
TABLE 6-2: RECOMMENDED
RESISTOR VALUES FOR
I
2
C ADDRESSING
Device #
Command
Byte
Values
R
XA
(k)R
XB
(k)
1 1100 000X ADDR pin tied to GND
2 1100 001X R
2A
= 10 R
2B
= 2.2
3 1100 010X R
3A
= 10 R
3B
= 4.3
4 1100 011X R
4A
= 10 R
4B
= 7.5
5 1100 100X R
5A
= 10 R
5B
= 13
6 1100 101X R
6A
= 10 R
6B
= 22
7 1100 110X R
7A
= 10 R
7B
= 43
8 1100 111X ADDR pin tied to V
DD
Note: Standard 5% tolerance resistors are used in
the table, however, 1% tolerance resistors
provide better ratio matching.
ADDR
ADDR
V
IN+
V
IN-
V
IN+
V
IN-
microcontroller
Unit 2/8
Unit 7/8
V
R
SS
V
IN
+,V
IN
-
Sampling
Switch
SS
R
S
C
SAMPLE
(3.2 pF)