Texas Instruments ADS126 EVM-PDK Series Скачать руководство пользователя страница 25 | Manualshive

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Texas Instruments ADS126 EVM-PDK Series Скачать руководство пользователя страница 25

Test DAC

6

ADS126xEVM Software

3.4.6

Tab 6: Test DAC

The

Test DAC

tab, as shown in

, controls the internal test DAC and is used to verify ADC

functionality by providing a known dc input voltage. The test DAC has two resistor divider taps that select
a fraction of the supply voltage. To use the test DAC, first select the

Pos. Test Signal Supply Ratio

and

Neg. Test Signal Supply Ratio

settings, and then connect the test DAC to ADC1, ADC2, or both, with the

Test DAC to ADCx

controls or with the MUX controls on tab 1 (

Input MUX

). Additionally, the test DAC

voltages are provided as outputs on pins AIN6 and AIN7 to be measured externally.

Figure 22. Tab 6 Settings

The

Test DAC Calculator

is provided to calculate the test DAC output and ADC input voltages based on

the supply ratios, AVDD, AVSS, and PGA gain settings. As an example, using the following settings:

•

Pos. Test Signal Supply Ratio = 0.525

•

Neg. Test Signal Supply Ratio = 0.475

•

Test DAC to ADC1 = Input to ADC1 (to select the Test DAC as the input source for ADC1)

•

PGA1 Gain = 1 V/V (on tab 1)

For a supply voltage of 5 V (AVDD – AVSS), the test DAC outputs (5 V) × (0.525 V – 0.475 V) × (1 V/V) =
0.25 V to ADC1.

To output or measure the test DAC voltage externally, set the

Test Signal Outputs

drop-down menu to

Connected to AIN6/AIN7

.

NOTE:

The test DAC is susceptible to power supply noise. Allow a sufficient margin of error when

verifying ADC conversion results with the test DAC.

Create a ratiometric measurement of the test DAC by selecting the analog supply as the
voltage reference source for the ADC. Then the matching input and reference noise cancels
in the ADC conversion result.

NOTE:

The software does not allow for simultaneous GPIO, Test DAC, IDAC, or VBIAS functions to

be enabled on the same pin.

25

SBAU206 – April 2015

ADS126xEVM-PDK

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Copyright © 2015, Texas Instruments Incorporated

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Содержание ADS126 EVM-PDK Series

Страница 1: ...of the hardware and software bill of materials and schematic for the ADS126xEVM Throughout this document the terms ADS126xEVM demonstration kit evaluation board evaluation module and EVM are synonymo...

Страница 2: ...onfiguration for the 6 V Wall Adapter 8 7 MMB0 Configuration for a Unipolar Bench Power Supply 9 8 MMB0 Configuration for a Bipolar Bench Power Supply 10 9 A Schematic of ADS126xEVM Clocking Circuitry...

Страница 3: ...ctions 6 3 J1 Serial Interface Header 12 4 ADS126x Analog Input Pin Functions 14 5 ADS126xEVM Bill of Materials 31 3 SBAU206 April 2015 ADS126xEVM PDK Submit Documentation Feedback Copyright 2015 Texa...

Страница 4: ...ponents and clock circuitry All these sections connect to the ADS126x TSSOP package located in the center of the EVM Figure 1 visually identifies each of these areas on the EVM Figure 1 ADS126xEVM Par...

Страница 5: ...current controlled reference voltage across JP3 Shorted R17 JP4 1 2 3 4 and 5 6 shorted Power supply connections to the ADS126x JP5 Shorted Connects the thermocouple input J4 1 to AINCOM for biasing S...

Страница 6: ...t SCLK J1 3 SCLK Serial clock SPI DIN J1 11 DIN Data in DOUT DRDY J1 13 DOUT Data out DRDY J1 15 DRDY Data ready 3 3 V J5 9 3 3V Digital supply Power 5 V J5 3 5V Analog supply Channels 0 5 J3 1 6 AIN0...

Страница 7: ...g the included 6 V wall adapter power supply An additional 5 V supply voltage is required when using the ADS126xEVM with bipolar supplies Configuring the EVM and MMB0 for each of these cases is demons...

Страница 8: ...MB0 board generates the 5 V analog supply and 3 3 V digital supply for the ADS126xEVM Figure 6 MMB0 Configuration for the 6 V Wall Adapter NOTE For clarity the ADS126xEVM daughter card is not shown in...

Страница 9: ...er supply to be connected to 5VA on the J14 terminal block Jumper J13B connects 5VA to 5VD and must remain shorted In this configuration the MMB0 derives the 3 3 V digital supply for the ADS126xEVM fr...

Страница 10: ...y to the 5VA net on terminal block J14 as shown in Figure 8 After the MMB0 is configured latch switch S2 on the ADS126xEVM into the 1 2 and 4 5 position switched to the right to select the bipolar sup...

Страница 11: ...S126xEVM has an onboard crystal oscillator component X1 The crystal oscillator clock is detected by the ADS126x when switch S1 is in the 1 2 position switched to the right as shown in Figure 9B 2 ADS1...

Страница 12: ...p CS 7 8 Unused select 100 k pull up Unused 9 10 GND Ground Serial port data input DIN 11 12 Unused Serial port data output and DOUT DRDY 13 14 data ready indicator active Unused low Data ready indica...

Страница 13: ...Top Side 1 2k R25 Input GND Configured for 250uA IDAC 1 2 JP1 Ratiometric Connection IN4 IN6 Jumper in single supply configuration Install 0 Ohms in R22 R24 R17 sets up a 1 95V reference voltage with...

Страница 14: ...c routine 2 6 1 2 IDAC Output The ADS126x provides dual matched current sources IDAC1 and IDAC2 for biasing of resistive temperature devices RTDs thermistors and other resistive based sensors The IDAC...

Страница 15: ...the J2 header on inputs IN7 IN6 and IN4 Two IDACs output 250 A each on pins AINCOM and AIN3 of the ADS126x Jumper wires then connect IN7 to COM and IN6 to IN3 These jumper wires route the IDAC curren...

Страница 16: ...3 surface mount pads to connect RT1 to inputs AIN6 and AIN7 on the ADS126x R23 is in parallel with RT1 for linearization of the thermistor resistance versus temperature transfer function NOTE Do not u...

Страница 17: ...s unable to connect to the EVM this driver may not have properly installed This driver may be reinstalled with one of the installers located at ftp ftp ti com pub data_acquisition ADCPro2 misc drivers...

Страница 18: ...eated to reload the plugin The plugin may need to be reloaded in the case of a communication failure or if power is cycled on the EVM hardware Figure 13 Loading the ADS1262EVM Plugin in ADCPro 2 Wait...

Страница 19: ...may precede steps 1 to 3 but is required before acquiring data in the next step Figure 16 Loading a Test Plugin in ADCPro 5 Acquire data by clicking the Acquire or Continuous button previously shown i...

Страница 20: ...s selects that function for both inputs and configures the PGA as recommended Note that the ADC2 radio buttons are only visible when an ADS1263EVM is connected Clicking the AINCOM button enables the V...

Страница 21: ...rence inputs and allows for fully flexible reference source inputs Figure 18 Tab 2 Settings When using an external reference source for ADC1 also make sure that the ADC1 REF Voltage field is matched t...

Страница 22: ...at least the ADC1 Data Rate setting because the firmware only polls for new ADC2 data when an ADC1 conversion completes Setting the ADC2 Data Rate much slower than the ADC1 Data Rate may require a muc...

Страница 23: ...ut Make sure to account for the analog filter settling time when enabling or disabling the burnout current source The Additional Settings controls configure other sensor bias related functions Input C...

Страница 24: ...ng the GPIO value does nothing when configured as an input Figure 21 Tab 5 Settings Clicking Read GPIO or modifying any of controls on this tab reads the GPIODAT register and updates all value indicat...

Страница 25: ...an example using the following settings Pos Test Signal Supply Ratio 0 525 Neg Test Signal Supply Ratio 0 475 Test DAC to ADC1 Input to ADC1 to select the Test DAC as the input source for ADC1 PGA1 G...

Страница 26: ...ta to Test Plug in control ADC2 data appear in the test plugin panel and ADC1 data appear in the ADCx Data graph However it is possible to switch between ADC1 and ADC2 data sets in the test plugin wit...

Страница 27: ...n the selected calibration routine During a calibration routine CAL in Progress lights up to show that the calibration process is ongoing If the calibration completes successfully CAL Completed lights...

Страница 28: ...ODE2 and ADC2CFG when applicable registers to nondefault ADS126x values indicated by asterisks in the register map table To revert all register settings back to the true ADS126x default values use the...

Страница 29: ...than the programmed alert value The pop up notifies the user of the estimated acquisition time and provides the option to continue or cancel the acquisition Cancelling an acquisition in progress requ...

Страница 30: ...of the STATUS byte error flags to check if any errors occurred in the previous acquisition as shown in Figure 28 This window automatically appears when an error flag is found in the acquired data set...

Страница 31: ...C32 7 2 33 pF C14 C15 CAP CERM 33 pF 50V NP0 5 0402 Yageo CC0402JRNPO9BN330 8 2 10 000 pF C19 C20 CAP CERM 0 01 uF 50V X7R 10 Yageo CC0402KRX7R9BB103 0402 9 2 0 1 uF C28 C33 CAP CERM 100 nF 50V X7R 1...

Страница 32: ...RT1 Thermistor NTC 2 2k Ohm 1 0805 Vishay NTCS0805E3222FMT 32 1 S1 SWITCH SLIDE SPDT GULLWING Copal Electronics CAS 120TB 33 1 S2 SWITCH SLIDE DPDT GULLWING Copal Electronics CAS 220TB 34 7 SH J1 SH...

Страница 33: ...PIC170A PIC170B PIC170G COC17 PIC1801 PIC1802 COC18 PIC1901 PIC1902 COC19 PIC2001 PIC2002 COC20 PIC2101 PIC2102 COC21 PIC2201 PIC2202 COC22 PIC2301 PIC2302 COC23 PIC240A PIC240B PIC240G COC24 PIC2501...

Страница 34: ...ing the warranty period to the address designated by TI and that are determined by TI not to conform to such warranty If TI elects to repair or replace such EVM TI shall have a reasonable time to repa...

Страница 35: ...transmitter has been approved by Industry Canada to operate with the antenna types listed in the user guide with the maximum permissible gain and required antenna impedance for each antenna type indic...

Страница 36: ...ified allowable ranges some circuit components may have elevated case temperatures These components include but are not limited to linear regulators switching transistors pass transistors current sens...

Страница 37: ...REMOVAL OR REINSTALLATION ANCILLARY COSTS TO THE PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES RETESTING OUTSIDE COMPUTER TIME LABOR COSTS LOSS OF GOODWILL LOSS OF PROFITS LOSS OF SAVINGS LOSS OF USE L...

Страница 38: ...sponsible for compliance with all legal regulatory and safety related requirements concerning its products and any use of TI components in its applications notwithstanding any applications related inf...

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