SBASBC4 December   2025 ADS8688W

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Switching Characteristics
    8. 6.8 Timing Diagrams
    9. 6.9 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Analog Inputs
      2. 7.3.2  Analog Input Impedance
      3. 7.3.3  Input Overvoltage Protection Circuit
      4. 7.3.4  Programmable Gain Amplifier (PGA)
      5. 7.3.5  Second-Order, Low-Pass Filter (LPF)
      6. 7.3.6  ADC Driver
      7. 7.3.7  Multiplexer (MUX)
      8. 7.3.8  Reference
        1. 7.3.8.1 Internal Reference
        2. 7.3.8.2 External Reference
      9. 7.3.9  Auxiliary Channel
        1. 7.3.9.1 Input Driver for the AUX Channel
      10. 7.3.10 ADC Transfer Function
      11. 7.3.11 Alarm Feature
    4. 7.4 Device Functional Modes
      1. 7.4.1 Device Interface
        1. 7.4.1.1 Digital Pin Description
          1. 7.4.1.1.1 CS (Input)
          2. 7.4.1.1.2 SCLK (Input)
          3. 7.4.1.1.3 SDI (Input)
          4. 7.4.1.1.4 SDO (Output)
          5. 7.4.1.1.5 DAISY (Input)
          6. 7.4.1.1.6 RST / PD (Input)
        2. 7.4.1.2 Data Acquisition Example
        3. 7.4.1.3 Host-to-Device Connection Topologies
          1. 7.4.1.3.1 Daisy-Chain Topology
          2. 7.4.1.3.2 Star Topology
      2. 7.4.2 Device Modes
        1. 7.4.2.1 Continued Operation in the Selected Mode (NO_OP)
        2. 7.4.2.2 Frame Abort Condition (FRAME_ABORT)
        3. 7.4.2.3 STANDBY Mode (STDBY)
        4. 7.4.2.4 Power-Down Mode (PWR_DN)
        5. 7.4.2.5 Auto Channel Enable With Reset (AUTO_RST)
        6. 7.4.2.6 Manual Channel n Select (MAN_Ch_n)
        7. 7.4.2.7 Channel Sequencing Modes
        8. 7.4.2.8 Reset Program Registers (RST)
  9. 8 Register Maps
    1. 8.1 Command Register Description
    2. 8.2 Program Register Description
      1. 8.2.1 Program Register Read/Write Operation
      2. 8.2.2 Program Register Map
        1. 8.2.2.1 Auto-Scan Sequencing Control Registers
          1. 8.2.2.1.1 Auto-Scan Sequence Enable Register (address = 01h)
          2. 8.2.2.1.2 Channel Power Down Register (address = 02h)
        2. 8.2.2.2 Alarm Flag Registers (Read-Only)
          1. 8.2.2.2.1 ALARM Overview Tripped-Flag Register (address = 10h)
          2. 8.2.2.2.2 Alarm Flag Registers: Tripped and Active (address = 11h to 14h)
          3. 8.2.2.2.3 Alarm Threshold Setting Registers
        3. 8.2.2.3 Device Features Selection Control Register (address = 03h)
        4. 8.2.2.4 Range Select Registers (addresses 05h-0Ch)
        5. 8.2.2.5 Command Read-Back Register (address = 3Fh)
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Phase-Compensated, 8-Channel, Multiplexed Data Acquisition System for Power Automation
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 78
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Documentation Support
      1. 10.1.1 Related Documentation
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information
8.2.2.1.2 Channel Power Down Register (address = 02h)

This register powers down individual channels that are not included for sequencing in AUTO_RST mode. The default value for this register is 00h, which implies that in default condition all channels are powered up. If all channels are powered down (that is, the value for this register is FFh), then the analog front-end circuits for all channels are powered down and the output of the ADC contains invalid data. If the device is in MAN-Ch_n mode and the selected channel is powered down, then the device yields invalid output that can also trigger a false alarm condition.

Figure 8-4 Channel Power Down Register
76543210
CH7_PD(1)CH6_PDCH5_PDCH4_PDCH3_PDCH2_PDCH1_PDCH0_PD
R/W-0hR/W-0hR/W-0hR/W-0hR/W-0hR/W-0hR/W-0hR/W-0h
LEGEND: R/W = Read/Write; -n = value after reset
(1) Shading indicates bits or registers that are not included in the 4-channel version of the device. A write operation on any of these bits or registers has no effect on device behavior. A read operation on any of these bits or registers outputs all 1's on the SDO line.
Table 8-6 Channel Power Down Register Field Descriptions
BitFieldTypeResetDescription
7CH7_PDR/W0hChannel 7 power-down.
0 = The analog front-end on channel 7 is powered up and channel 7 can be included in the AUTO_RST sequence
1 = The analog front-end on channel 7 is powered down and channel 7 cannot be included in the AUTO_RST sequence
6CH6_PDR/W0hChannel 6 power-down.
0 = The analog front-end on channel 6 is powered up and channel 6 can be included in the AUTO_RST sequence
1 = The analog front-end on channel 6 is powered down and channel 6 cannot be included in the AUTO_RST sequence
5CH5_PDR/W0hChannel 5 power-down.
0 = The analog front-end on channel 5 is powered up and channel 5 can be included in the AUTO_RST sequence
1 = The analog front-end on channel 5 is powered down and channel 5 cannot be included in the AUTO_RST sequence
4CH4_PDR/W0hChannel 4 power-down.
0 = The analog front-end on channel 4 is powered up and channel 4 can be included in the AUTO_RST sequence
1 = The analog front-end on channel 4 is powered down and channel 4 cannot be included in the AUTO_RST sequence
3CH3_PDR/W0hChannel 3 power-down.
0 = The analog front-end on channel 3 is powered up and channel 3 can be included in the AUTO_RST sequence
1 = The analog front end on channel 3 is powered down and channel 3 cannot be included in the AUTO_RST sequence
2CH2_PDR/W0hChannel 2 power-down.
0 = The analog front end on channel 2 is powered up and channel 2 can be included in the AUTO_RST sequence
1 = The analog front end on channel 2 is powered down and channel 2 cannot be included in the AUTO_RST sequence
1CH1_PDR/W0hChannel 1 power-down.
0 = The analog front end on channel 1 is powered up and channel 1 can be included in the AUTO_RST sequence
1 = The analog front end on channel 1 is powered down and channel 1 cannot be included in the AUTO_RST sequence
0CH0_PDR/W0hChannel 0 power-down.
0 = The analog front end on channel 0 is powered up and channel 0 can be included in the AUTO_RST sequence
1 = The analog front end on channel 0 is powered down and channel 0 cannot be included in the AUTO_RST sequence