SBASAW0 February   2024 ADS1288

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Timing Requirements: 1.65V ≤ IOVDD ≤ 1.95V and 2.7V ≤ IOVDD ≤ 3.6V
    7. 5.7 Switching Characteristics: 1.65V ≤ IOVDD ≤ 1.95V and 2.7V ≤ IOVDD ≤ 3.6V
    8. 5.8 Timing Diagrams
    9. 5.9 Typical Characteristics
  7. 6 Parameter Measurement Information
    1. 6.1 Noise Performance
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Analog Input
      2. 7.3.2 PGA and Buffer
        1. 7.3.2.1 Programmable Gain Amplifier (PGA)
        2. 7.3.2.2 Buffer Operation (PGA Bypass)
      3. 7.3.3 Voltage Reference Input
      4. 7.3.4 IOVDD Power Supply
      5. 7.3.5 Modulator
        1. 7.3.5.1 Modulator Overdrive
      6. 7.3.6 Digital Filter
        1. 7.3.6.1 Sinc Filter Section
        2. 7.3.6.2 FIR Filter Section
        3. 7.3.6.3 Group Delay and Step Response
          1. 7.3.6.3.1 Linear Phase Response
          2. 7.3.6.3.2 Minimum Phase Response
        4. 7.3.6.4 HPF Stage
      7. 7.3.7 Clock Input
      8. 7.3.8 GPIO
    4. 7.4 Device Functional Modes
      1. 7.4.1 Power-Down Mode
      2. 7.4.2 Reset
      3. 7.4.3 Synchronization
        1. 7.4.3.1 Pulse-Sync Mode
        2. 7.4.3.2 Continuous-Sync Mode
      4. 7.4.4 Sample Rate Converter
      5. 7.4.5 Offset and Gain Calibration
        1. 7.4.5.1 OFFSET Register
        2. 7.4.5.2 GAIN Register
        3. 7.4.5.3 Calibration Procedure
    5. 7.5 Programming
      1. 7.5.1 Serial Interface
        1. 7.5.1.1 Chip Select (CS)
        2. 7.5.1.2 Serial Clock (SCLK)
        3. 7.5.1.3 Data Input (DIN)
        4. 7.5.1.4 Data Output (DOUT)
        5. 7.5.1.5 Data Ready (DRDY)
      2. 7.5.2 Conversion Data Format
      3. 7.5.3 Commands
        1. 7.5.3.1  Single Byte Command
        2. 7.5.3.2  WAKEUP: Wake Command
        3. 7.5.3.3  STANDBY: Software Power-Down Command
        4. 7.5.3.4  SYNC: Synchronize Command
        5. 7.5.3.5  RESET: Reset Command
        6. 7.5.3.6  Read Data Direct
        7. 7.5.3.7  RDATA: Read Conversion Data Command
        8. 7.5.3.8  RREG: Read Register Command
        9. 7.5.3.9  WREG: Write Register Command
        10. 7.5.3.10 OFSCAL: Offset Calibration Command
        11. 7.5.3.11 GANCAL: Gain Calibration Command
  9. 8 Register Map
    1. 8.1 Register Descriptions
      1. 8.1.1 ID/SYNC: Device ID, SYNC Register (Address = 00h) [Reset = xxxx0010b]
      2. 8.1.2 CONFIG0: Configuration Register 0 (Address = 01h) [Reset = 92h]
      3. 8.1.3 CONFIG1: Configuration Register 1 (Address = 02h) [Reset = 10h]
      4. 8.1.4 HPF0, HPF1: High-Pass Filter Registers (Address = 03h, 04h) [Reset = 32h, 03h]
      5. 8.1.5 OFFSET0, OFFSET1, OFFSET2: Offset Calibration Registers (Address = 05h, 06h, 07h) [Reset = 00h, 00h, 00h]
      6. 8.1.6 GAIN0, GAIN1, GAIN2: Gain Calibration Registers (Address = 08h, 09h, 0Ah) [Reset = 00h, 00h, 40h]
      7. 8.1.7 GPIO: Digital Input/Output Register (Address = 0Bh) [Reset = 000xx000b]
      8. 8.1.8 SRC0, SRC1: Sample Rate Converter Registers (Address = 0Ch, 0Dh) [Reset = 00h, 80h]
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
      1. 9.3.1 Analog Power Supplies
      2. 9.3.2 Digital Power Supply
      3. 9.3.3 Grounds
      4. 9.3.4 Thermal Pad
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.3.2.1 Programmable Gain Amplifier (PGA)

The PGA is a low-noise, chopper-stabilized differential amplifier that extends the ADC dynamic range performance. The PGA provides analog gains from 1 to 16, with gains of 32 and 64 provided by digital scaling. The PGA output signal is routed to the CAPP and CAPN pins through 270Ω resistors. Connect an external 10nF, C0G-dielectric capacitor across these pins. An antialias filter is formed by these components to attenuate the signal level at the modulator aliasing frequency (fMOD).

As illustrated in Figure 7-4, the buffer is used between the PGA and the modulator. Connect two 47nF, C0G-dielectric capacitors from each buffer output to AVSS (CAPBP and CAPBN). A voltage charge pump increases the buffer input voltage headroom. Connect an external 4.7nF capacitor between CAPC and AGND for charge pump operation.

The PGA gain is programmed by the GAIN[2:0] bits of the CONFIG1 register. Table 7-2 shows the PGA gain settings and buffer selection.

Table 7-2 PGA Gains
GAIN[2:0] REGISTER BITSPGA GAININPUT SIGNAL RANGE (VPP)
0001±2.5
0012±1.25
0104±0.625
0118±0.3125
10016±0.15625
10132±0.078125
11064±0.0390625
111Buffer mode, gain = 1±2.5

Observe the PGA input and output voltage headroom specification. Figure 7-5 shows the input and output voltage headroom when operating with AVDD1 = 5V, an input common-mode voltage (VCM) = 2.5V, a differential input voltage = ±2.5VPP, and at gain = 1. The absolute minimum and maximum PGA input voltages (1.25V and 3.75V) are ±1/2 of the differential signal voltage plus the common-mode voltage. The PGA provides 0.15V input voltage margin at the negative peak and 0.4V input voltage margin at the positive peak. The PGA provides 1.1V output voltage margin at the positive and negative peaks.

GUID-20230718-SS0I-4CMJ-8JWX-S31KHKSXFQCP-low.svg Figure 7-5 PGA Headroom (AVDD1 = 5V, Gain = 1)

When operating with AVDD1 = 3.3V, the PGA cannot support ±2.5VPP input signals. Use the buffer for ±2.5VPP input signals. For ±1.25VPP input signals (PGA gain = 2), the input headroom is increased by increasing the common-mode voltage by 0.1V to AVSS + 1.75V. Figure 7-6 shows the input and output operating headroom for AVDD1 = 3.3V, VCM = 1.75V, input signal = ±1.25VPP, and gain = 2.

GUID-20220407-SS0I-CC4G-77KD-RLDJSCL1LJRB-low.svg Figure 7-6 PGA Headroom (AVDD1 = 3.3V, Gain = 2)