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Texas Instruments PGA309 Quick Start Manual
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Texas Instruments PGA309 Quick Start Manual

Texas Instruments PGA309 Quick Start Manual

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PGA309
Quick Start System Reference
Guide
by Art Kay
High-Precision Linear Products
SBOA103C
Jan 2006

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Summary of Contents for Texas Instruments PGA309

  • Page 1 PGA309 Quick Start System Reference Guide by Art Kay High-Precision Linear Products SBOA103C Jan 2006...
  • Page 2 PGA309 Quick Start SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...

  • Page 3: Table Of Contents

    PGA309 Quick Start Contents Required Equipment……………………………………………………..………4 Definition of sensor specifications………………………………………………5-12 PGA309 Absolute Calibration Example..……….………………………………13 Step 1: Will the PGA309 work for your application?..…..………………14-17 Step 2: Set up hardware……………………………………………..…..…18-21 Step 3: Configure PGA309 for initial scaling.……………………………..22-31 Step 4: Configure Sensor-Emulator-EVM to emulate sensor……………………………………………………...………….…..…32-38...
  • Page 4 • PGA309 Calculator – This software is used to do initial gain scaling and verify that the design does not violate any PGA309 specifications. Software is bundled with PGA309DK Board Interface software. •...
  • Page 5 SpanTC2 – The second order (quadratic) drift of the span. This coefficient is in % of span/ at room temperature. • PressureNonlinearity – The second order (quadratic) nonlinearity versus applied signal given in % of span. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 6 Span – the amount of change in normalized output voltage (in V/V) of the sensor over the entire range of applied stimulus. Offset – the normalized output of a sensor (in V/V) with no applied stimulus. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 7 1.5E-03 (T2, Offset2) (T3, Offset3) 1.0E-03 (22.5C, 1.02E-3) (T1, Offset1) (85C, 2.96E-6) (-40C, -1.62E-3) 5.0E-04 0.0E+00 -5.0E-04 Linear end point fit is used to Temp, degC determine the linear drift. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 8 The second order (quadratic) drift of 3.5E-03 the offset. This coefficient is in % of span/ at room temperature. 3.0E-03 2.5E-03 2.0E-03 offset span 1.5E-03 1.0E-03 5.0E-04 0.0E+00 -5.0E-04 Temp, degC SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 9 SpanTC1 6.255 10 − × ⋅ − − ( ) 3.6734 10 Bridge Sensitivity vs T emp 4.0E-03 3.5E-03 3.0E-03 2.5E-03 2.0E-03 offset span 1.5E-03 1.0E-03 5.0E-04 0.0E+00 -5.0E-04 Temp, degC SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 10 This coefficient is in % of 3.5E-03 span/ at room temperature. 3.0E-03 (T3, Span3) (T2, Span2) (T1, Span1) (85C, 3.73E-3) 2.5E-03 (22.5C, 3.67E-3) (-40C, 3.44E-3) 2.0E-03 offset span 1.5E-03 1.0E-03 5.0E-04 0.0E+00 -5.0E-04 Temp, degC SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 11 So, Sensor Output vs Applied Stimulus real_sensor100 is the span of the sensor at room temperature. 4.00E-03 3.50E-03 3.00E-03 2.50E-03 ideal span 2.00E-03 span 1.50E-03 1.00E-03 5.00E-04 0.00E+00 Applied Stimulus (%) SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 12 SensorOutput P T , ⋅ ⋅ ⋅ Offset room Span room Offset_TC T ( ) Span Span_TC T ( )     * Available for download at www.ti.com as SBOC065 SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...

  • Page 13: Pga309 Absolute Calibration Example

    For this quick start example the specifications below and the example hardware configuration will be used. The Sensor-Emulator-EVM will create an equivalent for the illustrated Real World Inputs. “generate_sim_values.xls “Offset and Span” Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...

  • Page 14: Sensor

    Calculator software tool (SLVC073) to see if the PGA309 has the gain and offset adjustment range required to accommodate your sensor. • Use the PGA309 Calculator software tool to verify that your design does not violate any of the most critical PGA309 specifications (internal or external nodes).
  • Page 15 Enter your sensor parameters and your PGA309 configuration parameters to get the gain scaling. Enter Press Compute information Constants and here. For the resulting gain example, settings will be enter the displayed here. values shown. If your design generates values...
  • Page 16 Click Apply Constraints and then click Compute Constants. In this case the range of adjustment for the Zero DAC is reduced but is still adequate to correct for the sensor drift. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 17 After the gains and offsets of the PGA309 have been calculated, press Simulate Device to see if any internal nodes are out of range. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 18 This diagram illustrates an example of how the Sensor-Emulator-EVM would be used in an engineering bench setup. The PGA309 is a programmable sensor signal conditioning chip. The Sensor-Emulator-EVM can be used in conjunction with the PGA309EVM (both versions) to facilitate the development of the PGA309 application.
  • Page 19 Jumper setup of PGA309EVM-xx and connections to PC, power, and the Sensor-Emulator-EVM SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 20 Electrical Required Connections to Sensor-Emulator-EVM SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 21 JUMP5 to the channels are not allow the on-board position shown used in this mode. voltage reference to connect GND to generate the to the bottom of emulated diode the bridge voltages. emulator. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 22 Step 3: Do initial setup of the PGA309 using the PGA309 DK Program • Copy the PGA309 Calculator results into the PGA309DK software. • Configure the PGA309 Temp ADC • Calibrate the ADS1100 (ADC on PGA309EVM-xx PC Interface Board Used to read the PGA309 output;...
  • Page 23 Start the PGA309 Designer’s Kit Control Program. When it starts, a message box will ask if you want to load from the EEPROM (Press No). Another box will indicate that “the PGA309 EVM was detected using the One-Wire interface.” If the PGA309EVM does not work properly, refer to the PGA309EVM Users Guide.
  • Page 24 For this example, we will measure the PGA309 output voltage using an delta-sigma A/D converter on the PGA309 PC Interface Board (the ADS1100). For optimal accuracy the ADS1100 should be calibrated. To calibrate the ADS1100, measure the supply voltage Vs on the PGA309 PC Interface Board (this should be close to 5V).
  • Page 25 Press the Board Settings button to enter the calibration factors. Enter the measured value for Vs then click Read ADS1100. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 26 For the next part of the ADS1100 calibration, the input of the ADS1100 is shorted. The two boards must be separated so that the PGA309 output is not shorted by the calibration. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 27 The calibration will take a few seconds. When it is complete close the window. When this step is done, plug the two PGA309EVM boards back together. At this point the calibration is complete. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 28 Step B: Make sure PGA309 Test Pin HIGH is checked. During calibration, the PGA309 test pin must be set high. This pin prevents the PGA309 from reading the EEPROM during calibration. SBOA103C...
  • Page 29 Set the reference and bridge excitation voltage to the proper values used in the PGA309 Calculator. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 30 Copy the gain and offset settings from the PGA309 Calculator to the PGA309 Designer’s Kit Control Program. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 31 Step C: Press Write PGA309 to copy all the information entered in the program into the registers of the PGA309. Step A: Configure the temperature ADC by pressing the ADC Config button. The example settings Step B: shown are good for a diode measurement.

  • Page 32: Step 4: Configure Sensor-Emulator-Evm To Emulate

    For our tools we will mathematically define the specifications. You may have to translate your particular specifications to our format. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 33 If the raw output of the sensor is not known, the “Generate_Sim_Values.xls” spreadsheet can be used to translate the specifications of your bridge sensor and temperature sensor to system voltage levels. The spreadsheet contains five sections (Offset and Span, Diode Vo, Rt-, Rt+, PGA309 Error, Ratiometric Error): Offset and Span: Generates the bridge output voltages.
  • Page 34 Sensor-Emulator-EVM. Enter these for our example Set Sensor-Emulator-EVM potentiometers to generate these voltages as detailed in pages 35-36 SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 35 When the channel is selected, LED D101 will light to indicate that the correct channel is selected. Bridge Sensitivity v s Temp 4.5E-03 4.0E-03 3.5E-03 3.0E-03 2.5E-03 2.0E-03 offset span 1.5E-03 1.0E-03 5.0E-04 0.0E+00 -5.0E-04 -1.0E-03 Tem p, degC SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 36 LED D103 will light to indicate that the correct channel is selected. Bridge Sensitivity v s Temp 4.5E-03 4.0E-03 3.5E-03 3.0E-03 2.5E-03 2.0E-03 offset span 1.5E-03 1.0E-03 5.0E-04 0.0E+00 -5.0E-04 -1.0E-03 Tem p, degC SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 37 Note that the Temp ADC areas are specific to the PGA309 sensor signal conditioning chip. The Temp ADC values will be used in the computation of the Counts for the temp ADC. The next several pages will show how the diode voltages are used to program the sensor Sensor-Emulator-EVM.
  • Page 38 The rotary switch S2 is used to select this channel. When the channel is selected, LED D201 will light to indicate that the correct channel is selected. Note when emulating Diode temperature control, the Rt temperature section is not used. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 39 Step 5: Use the PGA309 Calibration Spreadsheet • Select the calibration algorithm • Copy the PGA309 registers into the spreadsheet • Use the Sensor-Emulator-EVM to generate the sensor outputs over temperature. • Store calibration results into a file. Load this into the PGA309 external EEPROM.
  • Page 40 For this example, use the PGA309 Calibration Spreadsheet. This tool uses measured data (pressure and temperature) to create a lookup table that the PGA309 will use to compensate for offset and gain drift. The spreadsheet will also generate a coefficient that the PGA309 will use to correct for nonlinearity verses applied pressure.
  • Page 41 Press Load registers from PGA309 to copy the registers from the evaluation fixture into the spreadsheet. PGA309 Calibration Spreadsheet, Main Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 42 Press Prepare Calibration Sheet to select the algorithm. In this example, we will do a 3 temperature 3 pressure calibration. Press OK after you have selected 3 Temperature 3 Pressure calibration. PGA309 Calibration Spreadsheet, Main Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 43 Next the program will ask what type of Temperature Measurement Method you want to use. For this example, we use the diode method. PGA309 Calibration Spreadsheet, Sensor Curvefit Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 44 When the template for your calibration algorithm is loaded this box will pop up. Press OK. PGA309 Calibration Spreadsheet, Sensor Curvefit Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 45 When the Load registers from PGA309 button on the Main sheet was pressed, the PGA309 registers were copied into this section of the Sensor Curvefit sheet. PGA309 Calibration Spreadsheet, Sensor Curvefit Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 46 The appropriate values need to be entered manually for the measurement temperatures. The measurement temperatures are the temperatures that the calibration measurements are made PGA309 Calibration Spreadsheet, Sensor Curvefit Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 47 The easiest way of doing this is to select a cell and press the Insert TempADC reading in active cell button. This will insert a PGA309 Temp ADC in counts into that cell. The measured PGA309 Temp ADC readings need to be recorded at the respective applied temperatures.
  • Page 48 PGA309 output voltage reading from the ADS1100 delta sigma ADC into that cell. The PGA309 output voltage needs to be recorded at the appropriate applied pressure and temperature. Use the bridge selector switch on the Sensor-Emulator-EVM to generate...
  • Page 49 Curvefit sheet. These graphs are an easy way to check for gross problems. The graphs shown are indicative of typical results for example. PGA309 Calibration Spreadsheet, Sensor Curvefit Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 50 Enter the output voltage scale, the number of points in the table, and the look up table temperature range. For our example, enter the values shown. PGA309 Calibration Spreadsheet, Calibration Results Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 51 This range must be a subset of Range1. It is OK for range 1 PGA309 Calibration Spreadsheet, Calibration and range 3 to be equivalent. Results Tab PGA309 Calibration Spreadsheet, Sensor Curvefit Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 52 Note gain and offset the output should ranges in the approximately match the calibration values entered in the Enter table. Output Scale section. PGA309 Calibration Spreadsheet, Calibration Results Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 53 Calibration Results tab on the spreadsheet. At this point the initial calibration is complete and the table can be uploaded into the PGA309 EEPROM. PGA309 Calibration Spreadsheet, Calibration Results Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 54 Press the Save Registers + Lookup Table button. This will store the lookup table into a file that can be loaded into the PGA309 EEPROM. PGA309 Calibration Spreadsheet, Main Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 55 Make sure the PGA309 Test Pin Press Write EEPROM to High box is not checked. When in store the lookup table in this mode the PGA309 will read the the external EEPROM . EEPROM and adjust offset and gain for each temperature...
  • Page 56 The PGA309 Error tab on the generate_sim_values.xls is a convenient way to do a post calibration error analysis. To use it select the blue cell corresponding to the current setup, and press the Insert Vout reading in active cell button. This will insert the PGA309 output reading from the ADS1100.
  • Page 57 100% pressure at room temperature. Note the correction factors are developed based on these readings. These are used to calibrate the Lin_Dac errors not PGA309 Calibration Spreadsheet, Sensor previously Curvefit Tab accounted for. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 58 After making the secondary calibration measurements, store the calibration results into a file and load them into the PGA309 as with the first calibration. The file for this example calibration is saved on the PGA309 Quick Start Disk and is called quick_start_second.txt.
  • Page 59 Post- secondary calibration errors are typically on the order of 0.05%. The secondary calibration involves making two measurements at room temperature. generate_sim_values.xls, PGA309 Error Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...

  • Page 60: Pga309 Ratiometric Calibration Example

    This document describes the key elements that are required in a ratiometric calibration, but does not fully explain how to use the PGA309 Gain Calculator, Sensor-Emulator-EVM, or the Designers Kit Control Program.

  • Page 61: Sboa103C Jan

    Diode. Note that the device power supply is used to provide excitation for the PGA309 sensor. So for this configuration, the Vexc pin on the PGA309 is not used and Vin- consequently, the PGA309 cannot correct for nonlinearity Temp verses applied stimulus.
  • Page 62 This diagram illustrates PGA309EVM jumper settings for a ratiometric system. Sensor-Emulator-EVM connections and power connections are also shown. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 63 Required Electrical Connections to Sensor-Emulator-EVM SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 64 Set the jumper shown to allow the JUMP5 to the on-board voltage position shown to reference to generate connect GND to the emulated diode the bottom of the voltages. bridge emulator. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 65 The PGA309 Calculator can be used to compute the gain and offset settings for the PGA309. These are the values used for this ratiometric example configuration. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 66 In the ratiometric configuration, the power supply (Vs) is being used as the reference. Thus, it is very important that the supply is measured during calibration. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 67 Configure the initial settings of the PGA309 Step A During calibration, the PGA309 Test Pin High must be checked to prevent the PGA309 from reading the EEPROM during calibration. Step B The gain and offset values computed by the calculator need to be written into the PGA309 using the PGA309 Designer’s Kit...
  • Page 68 Set up the PGA309 Temperature ADC Configure the Temp ADC as shown and click OK. From the main window, press Write PGA309. The configuration shown was selected for this example (diode measurement using the built-in 2.048V reference). It is important to use the built in ADC...
  • Page 69 Note that Pressure Nonlin is zero. The sensor must be linear for this configuration because the sensor excitation is the power supply and so the nonlinearity correction circuit cannot be used. generate_sim_values.xls, Offset and Span Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 70 The bridge output versus applied stimulus is also displayed. This must be a linear function for a ratiometric setup that does not use Vexc for bridge excitation. generate_sim_values.xls, Offset and Span Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 71 1.5E-03 1.0E-03 5.0E-04 0.0E+00 -5.0E-04 -1.0E-03 Tem p, degC For this ratiometric example adjust the potentiometer on the Sensor- Emulator-EVM to the bridge section to produce the respective voltages shown. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 72 It is used to compute diode voltages that are used to set up the Sensor-Emulator-EVM. For this ratiometric example, adjust the potentiometer on the Sensor-Emulator- EVM to the diode temperature section to product the respective counts shown for temperature. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 73 (pressure and temperature) to create a lookup table that the PGA309 will use to compensate for offset and gain drift. The spreadsheet will also generate a coefficient that the PGA309 will use to correct for nonlinearity verses applied pressure.
  • Page 74 Press Prepare Calibration Sheet to select the algorithm. In this example, we will do a 3 pressure 3 temperature calibration. Press OK after you have selected 3 Temperature 3 Pressure calibration. PGA309 Calibration Spreadsheet, Main Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 75 Next, the program will ask what type of Temperature Measurement Method you want to use. For this example, we use the diode method. PGA309 Calibration Spreadsheet, Sensor SBOA103C Curvefit Tab PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 76 This are contains the PGA309 settings. These settings are loaded into these cells when the Load Registers From PGA309 button was pressed from the main tab. The temperature ranges and pressure ranges need to be entered by hand. The TempADC...
  • Page 77 Vexc is disabled. correction is not used. This value will not be used to generate the calibration tables in the EEPROM. PGA309 Calibration Spreadsheet, Sensor Curvefit Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 78 The secondary calibration is used to correct for errors introduced by the LinDac. So, for this example, this section is left blank. PGA309 Calibration Spreadsheet, Sensor SBOA103C Curvefit Tab PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 79 Select the desired Select the post-calibration temperature range of Make sure the Result output range. the look-up-table. Sanity Check passes. PGA309 Calibration Spreadsheet, Calibration Results Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 80 The spreadsheet will let you know that Excitation is Disabled. This is normal for the ratiometric method. Press Save Registers+Lookup Table. PGA309 Calibration Spreadsheet, Main Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 81 Step A Step D Press the Open File Press the Read PGA309 to see the button to get the file updated register values. containing the calibration results. Step B Step C Make sure the PGA309 Test Pin High Press Write EEPROM to box is not checked.
  • Page 82 The PGA309 RatioMetric Error tab on the generate_sim_values.xls is a convenient way to do a post-calibration error analysis. To use it, select the blue cell corresponding to the current setup, and press the Insert Vout reading in active cell button. This will insert the PGA309 output reading from the ADS1100.
  • Page 83 For the ratiometric calibration method it is useful to adjust the power supply to see how PSR Schematic affects the PGA309 calibrated accuracy. A 10% power supply PGA309 PC Interface Board deviation is used in this example because it is a typical worst case INPU deviation for ratiometric systems.
  • Page 84 Make sure that you measure the supply voltage (Vs) and enter it into the PGA309 Designer’s Kit Control Program. SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 85 Measure the PGA309 post calibration error at a different supply voltage to see the affect of PSR on error. For this example, the supply was changed from Vs= 4.963V to Vs=4.457V and the average error changed from -0.06% to -0.03%.

  • Page 86: Pga309 With Output Scaling Example

    In many applications an external gain stage is used to get an output swing beyond the range of the PGA309. The circuit shown below is a typical example of gain scaling with an offset shift. The PGA309 calibration spreadsheet can accommodate external gain and offset scaling. Doing the calibration by measuring the output of the external gain stage will calibrate out errors caused by resistor tolerance in the external stage.
  • Page 87 ⋅ Equation 2: solve Equation 1 for Rf 2500. can be used to take the 0.5V − 2500. to 4.5V output of the PGA309         and re-scale it to 0V to 10V. ⋅...
  • Page 88 PGA309 With Output Scaling (0 to 10V) The “ExtraGain” and “ExtraOffset” factor are entered here on the spreadsheet. Normally these are set to ExtraGain = 1.0 and ExtraOffset = 0.0. PGA309 Calibration Spreadsheet, Sensor Curvefit Tab SBOA103C PGA309 Quick Start...
  • Page 89 PGA309 With Output Scaling (0 to 10V) The data that is measured at the output of the external amplifier is entered directly into the spreadsheet. PGA309 Calibration Spreadsheet, Sensor Curvefit Tab SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 90 PGA309 With Output Scaling (0 to 10V) Other then these few minor changes, the calibration method is the same as the other examples. The output range must be include the scaling stage. PGA309 Calibration Spreadsheet, Calibration Results Tab SBOA103C PGA309 Quick Start...
  • Page 91 PGA309 With Output Scaling (4mA to 20mA) The spreadsheet can also be used to calibrate a system using a PGA309 with a 4mA to 20mA output scaling. ⋅ I out I in I ref   V in V ref ...
  • Page 92 ⋅ Equation 2: solve Equation 1 for R1 12500. − 62500. can be used to take the 0.5V to 4.5V output of the PGA309   − ⋅ ⋅   Equation 3: Vin=4.5V, Iout = 20mA...
  • Page 93 PGA309 With Output Scaling (4mA to 20mA) The “ExtraGain” and “ExtraOffset” factor are entered here on the spreadsheet. Normally these are set to ExtraGain = 1.0 and ExtraOffset = 0.0. PGA309 Calibration Spreadsheet, Sensor Curvefit Tab SBOA103C PGA309 Quick Start...
  • Page 94 PGA309 With Output Scaling (4mA to 20mA) The data that is measured at the output of the voltage to current converter is entered PGA309 Calibration directly into the spreadsheet Spreadsheet, Sensor (in Amps). Curvefit Tab SBOA103C PGA309 Quick Start Jan 2006...
  • Page 95 PGA309 With Output Scaling (4mA to 20mA) Other then these few minor changes, the calibration method is the same as the other examples. The output range must be include the scaling stage (in Amps). PGA309 Calibration Spreadsheet, Calibration Results Tab...

  • Page 96: Pga309 In Three-Wire Mode

    PGA309 In Three Wire Mode In many cases the PGA309 is connected in a configuration referred to as a three wire connection. In this configuration the only wires that need to connect to the sensor module are power, ground, and Vout. In this configuration the One-Wire digital communication line is connected to the Vout pin.
  • Page 97 PGA309 In Three Wire Mode If the “Set PreCal EE” feature is used the test pin is normally grounded (leave “PGA309 Test Pin HIGH” box unchecked). SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 98 PGA309 In Three Wire Mode A key technique used in calibration is to use the test pin on the PGA309. The test pin is typically used during calibration to place the PGA309 into test mode. The main benefit of test mode is that the Gain DAC and Offset DAC are forced to remain at the last values written to their respective registers.
  • Page 99 PGA309 In Three Wire Mode When using this feature, first set all the registers to values your application requires. Then press the “Set PreCal EE” button. Step 2 Step 1 SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 100 After Pressing the “Set PreCal EE” a dialogue box will pop up that verifies the value of the Zero DAC and Gain Dac you want in your EEPROM configuration. After creating the EEPROM table, the PGA309 Designer’s Kit Control Program is ready for to be used with the calibration spreadsheet.
  • Page 101 SBOA103C PGA309 Quick Start Jan 2006 System Reference Guide...
  • Page 102 TI product or service and is an unfair and deceptive business practice. TI is not responsible or liable for any such statements. Following are URLs where you can obtain information on other Texas Instruments products and application solutions:...