SBAU126E may   2007  – june 2023 ADS1158 , ADS1258

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1ADS1258EVM Overview
    1. 1.1 ADS1258EVM Kit
    2. 1.2 ADS1258EVM
  5. 2Getting Started With the ADS1258EVM
  6. 3Analog Interface
    1. 3.1 Analog Input Options
    2. 3.2 ADC Connections and Decoupling
    3. 3.3 Configurable Multiplexer Loop
      1. 3.3.1 Measuring Single-Ended Inputs Using a Pseudo-Differential Configuration
    4. 3.4 Clocking
    5. 3.5 Voltage Reference
  7. 4Digital Interface
    1. 4.1 GPIO
  8. 5Power Supplies
  9. 6Software Installation
  10. 7EVM Operation and GUI
    1. 7.1 Connecting the Hardware
    2. 7.2 EVM GUI Global Settings for ADC Control
    3. 7.3 Time-Domain Display
    4. 7.4 Frequency-Domain Display
    5. 7.5 Histogram Display
  11. 8Bill of Materials, Layout, and Schematics
    1. 8.1 Bill of Materials
    2. 8.2 EVM PCB Layout
    3. 8.3 Schematics
  12. 9Revision History

3.5 Voltage Reference

The ADS1258EVM requires a precision reference voltage to accurately convert the analog inputs to digital outputs. Figure 3-6 shows the EVM voltage reference circuitry.

GUID-20221026-SS0I-HRDZ-K5PL-ZDVTZZ92HJKD-low.svg Figure 3-6 ADS1258EVM Voltage Reference Circuit

The EVM includes two options to provide a reference voltage to the ADC. The first option is an installed component: the low-noise, low-drift, buffered-output REF6025. This discrete voltage reference outputs a voltage of 2.5 V to the ADC reference pins (REFOUT and ground). Additionally, the REF6025 output voltage is also connected to the J3 terminal block as REFOUT.

The second voltage reference option on the EVM is to use an external voltage source. An external component can be useful if a reference voltage other than 2.5 V is required. Configure the EVM for an external voltage reference by moving the 0-Ω resistor at R4 to R2. Then connect EXT_VREFP on J3 to the external reference output voltage, and connect the external reference ground to the EVM ground. REFOUT on J3 is shorted to EXT_VREFP to make sure that the reference voltage can still be used to bias external circuitry. See the ADS1258 data sheet for information about the allowable voltage range on the VREFx pins.