DEMO MANUAL DC2608

DC2210 Experimenter Board (Included in DC2608 Kit)

The DC2210 experimenter board (see Figure 3) brings all LTC2986-1 channels plus the COM connection out to a proto area and a 24-position terminal block. The user may connect any of the supported sensors and sense resistors to any of the LTC2986-1 inputs in this area. Figure 4 shows the connection schematic of the DC2210 Experimenter board. Please note that only CH1 to CH10 are valid on the DC2210 when used in conjunction with the DC2618.

DC2211 Universal Temperature Measurement Board

The universal temperature measurement board (see Figure 5) allows the user to connect any of the LTC2986-1 supported sensors to the DC2618 demo board.

The universal temperature measurement board has a built-in sense resistor for RTD applications as well as a cold junction sensor diode for thermocouple applications (see Figure 6 for the DC2211 schematic diagram). The sense resistor is a 2kΩ ±0.1% 10ppm/°C sense resistor on channels 1 and 2 which may be used with any of the supported RTD sensor types. The precise value of this sense resistor is stored in an on-board EEPROM. The LTC2986-1 demo software can read this EEPROM and use to configure the sense resistor value in the LTC2986-1's configuration memory.

The external interface on the universal temperature measurement board is an 8-position screw-terminal block with the flowing pinout.

DC2211 Universal Temperature Measurement Daughter Board Examples

• Four thermocouples connected to positions A-D with the negative connections tied to positions E-H using the on-board diode as cold junction sensor (see Figure 7a for the schematic and Figure 8a for the corresponding software configuration).
• A 4-wire RTD connected to positions A-D using the on-board sense resistor as the ratiometric reference (see Figure 7b for the schematic and Figure 8b for the corresponding software configuration).

DC2212 Thermocouple Daughter Board

The thermocouple board (see Figure 9) demonstrates the flexibility, accuracy, and low noise features of the LTC2986-1 thermocouple modes.

If the user wishes to connect external sensors to the thermocouple board, two universal-type thermocouple jacks (J2 and J3) are provided (see schematic diagram Figure 10 and corresponding software configuration Figure 11). The user may connect any of the LTC2986-1 supported thermocouples (B, E, J, K, N, R, S, or T) as well as custom thermocouples through these jacks.

To demonstrate the flexibility of the LTC2986-1, the thermocouple board includes cold junction diodes (Q1 and Q2) embedded in each thermocouple socket. Alternatively, a 4-wire PT100 RTD (R5) can be used as the cold junction sensor for either or both thermocouples.

To demonstrate the low system noise and offset of the LTC2986-1, the thermocouple board provides a short to ground on channel 5.

To demonstrate the accuracy of the LTC2986-1, the thermocouple board allows the user to connect a thermocouple calibrator or an external voltage source to CH10 of the LTC2986-1 through a pair of banana jacks (J4 and J5).

DC2213 Dedicated RTD Board

The DC2213 dedicated RTD board (see Figure 12) demonstrates the flexibility, accuracy, and low noise features of the LTC2986-1 RTD sensor modes. The DC2213 provides several circuits demonstrating the features of the LTC2986-1.

The DC2213 (see schematic diagram Figure 13 and corresponding software configuration Figure 14) provides a 2kΩ ±0.1% 10ppm/°C sense resistor on channels 2 and 3 which may be used with any of the RTD sensor circuits on this board. An additional Kelvin connection is also provided to this sense resistor on channel 1. The precise measured value of this sense resistor is stored in an on-board EEPROM which the LTC2986-1 demo software can read and use to configure the sense resistor value.

To demonstrate the low system noise of the LTC2986-1, the dedicated RTD board provides a 0°C PT100 simulator (100Ω ±0.01% 10ppm/°C) on channels 3 to 6 configured as a 4-wire sensor. In addition to this the user may use this circuit to demonstrate how the rotated mode eliminates measurement error introduced by parasitic thermocouples. To facilitate this measurement, the DC2213 provides an external thermocouple interface which acts as a parasitic thermocouple.

To see the effects of parasitic thermocouples on non-rotated measurement modes, first measure the on-board 0°C PT100 simulator in a non-rotated configuration and see the measurement error as the thermocouple's temperature changes. To see the benefit of the rotated measurement mode, switch from the no rotation/sharing to the rotation/ sharing configuration and see the errors introduced by the parasitic thermocouple minimized.

In addition to the fixed value RTD simulator, there is also a variable resistor RTD simulator. This circuit can be used to demonstrate the range of the various LTC2986-1 RTD sensor modes as well as demonstrate the fault detection capabilities of the LTC2986-1. Please note that the variable resistor feature of the DC2213 requires channel 11 and will not work with the DC2618.

If the user wishes to connect an external RTD to the sensor board, a 4-position terminal block is provided. The user may connect any of the LTC2986-1 supported RTDs as well as custom RTDs to the DC2618 demo board through this interface. The interface may be configured for 3 or 4 wire sensors. To demonstrate the accuracy of the LTC2986-1, the user may also connect an RTD calibrator or precision resistors to this interface.

DC2214 Dedicated Thermistor Board

The DC2214 dedicated thermistor board includes several circuits (see Figure 15) to demonstrate the flexibility, accuracy, and low noise features of the LTC2986-1 thermistor sensor modes.

The DC2214 provides a 10kΩ ±0.1% 15ppm/°C sense resistor on channels 1 and 2 which is shared with all of the thermistor sensor circuits on this board (see schematic diagram Figure 16 and corresponding software configuration Figure 17). The measured value of this sense resistor is stored in an on-board EEPROM which the LTC2986-1 demo software can read and use to configure the sense resistor value.

To demonstrate the low system noise of the LTC2986-1, the dedicated thermistor board provides a 25°C 10k thermistor simulator (10kΩ ±0.1% 15ppm/°C) on channels 2-4 configured as a differential sensor. In addition to this the user may use this circuit to demonstrate how the rotated mode eliminates measurement error introduced by parasitic thermocouples. To facilitate this demonstration the DC2214 provides an external thermocouple interface which acts as a parasitic thermocouple.

To see the effects of parasitic thermocouples on non-rotated measurement modes, first measure the on-board 25°C 10k thermistor simulator in a no-rotation/sharing configuration and see the measurement error as the thermocouple's temperature changes. To see the benefit of the rotated measurement mode, switch to the rotation/ sharing configuration and see the errors introduced by the parasitic thermocouple disappear (the effects are more significant with lower excitation current).

The DC2214 also includes a 499kΩ (0.1% 15ppm/°C) thermistor simulator on channels 9 and 10. Ideally, this resistor simulates –30.59°C for a 44008 (30k) thermistor and –51.94°C for a 44006 (10k) thermistor. Note, the 10k thermistor reports the temperature, but also indicates a soft fault since the temperature is below the thermistor's specified minimum temperature.

In addition to the fixed value thermistor simulators, there is a variable resistor thermistor simulator as well. This circuit can be used to demonstrate the range of the various LTC2986-1 thermistor sensor modes as well as demonstrate the fault detection capabilities of the LTC2986-1.

If the user wishes to connect an external thermistor to the daughter board, a 2-position terminal block is provided. The user may connect any of the LTC2986-1 supported thermistors as well as custom thermistors to the DC2618 demo board through this interface. To demonstrate the accuracy of the LTC2986-1, the user may connect external resistance standards to this interface.