SBAS871C August   2017  – January 2019 DAC60504 , DAC70504 , DAC80504

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Block Diagram
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Digital-to-Analog Converter (DAC)
        1. 8.3.1.1 DAC Transfer Function
        2. 8.3.1.2 Output Amplifiers
        3. 8.3.1.3 DAC Register Structure
          1. 8.3.1.3.1 DAC Register Synchronous and Asynchronous Updates
          2. 8.3.1.3.2 Broadcast DAC Register
      2. 8.3.2 Internal Reference
        1. 8.3.2.1 Reference Divider
        2. 8.3.2.2 Solder Heat Reflow
      3. 8.3.3 Device Reset Options
        1. 8.3.3.1 Power-on-Reset (POR)
        2. 8.3.3.2 Software Reset
    4. 8.4 Device Functional Modes
      1. 8.4.1 Stand-Alone Operation
      2. 8.4.2 Daisy-Chain Operation
      3. 8.4.3 Frame Error Checking
      4. 8.4.4 Power-Down Mode
    5. 8.5 Programming
    6. 8.6 Register Map
      1. 8.6.1 NOP Register (address = 0x00) [reset = 0x0000]
        1. Table 9. NOP Register Field Descriptions
      2. 8.6.2 DEVICE ID Register (address = 0x01) [reset = 0x---]
        1. Table 10. DEVICE ID Field Descriptions
      3. 8.6.3 SYNC Register (address = 0x2) [reset = 0xFF00]
        1. Table 11. SYNC Register Field Descriptions
      4. 8.6.4 CONFIG Register (address = 0x3) [reset = 0x0000]
        1. Table 12. CONFIG Register Field Descriptions
      5. 8.6.5 GAIN Register (address = 0x04) [reset = 0x---]
        1. Table 13. GAIN Register Field Descriptions
      6. 8.6.6 TRIGGER Register (address = 0x05) [reset = 0x0000]
        1. Table 14. TRIGGER Register Field Descriptions
      7. 8.6.7 BRDCAST Register (address = 0x6) [reset = 0x0000]
        1. Table 15. BRDCAST Register Field Descriptions
      8. 8.6.8 STATUS Register (address = 0x7) [reset = 0x0000]
        1. Table 16. STATUS Register Field Descriptions
      9. 8.6.9 DACx Register (address = 0x8 to 0xF) [reset = 0x0000 or 0x8000]
        1. Table 17. DACx Register Field Descriptions
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Interfacing to a Microcontroller
      2. 9.1.2 Programmable Current Source Circuit
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Related Links
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Community Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

8.4.3 Frame Error Checking

If the DACx0504 is used in a noisy environment, error checking can be used to check the integrity of SPI data communication between the device and the host processor. This feature can be enabled by setting the CRC-EN bit in the CONFIG register.

The error checking scheme is based on the CRC-8-ATM (HEC) polynomial x8 + x2 + x + 1 (that is, 100000111). When error checking is enabled, the serial interface access cycle width is 32 bits. The normal 24-bit SPI data are appended with an 8-bit CRC polynomial by the host processor before feeding it to the device, as shown in Table 4. In all serial interface readback operations the CRC polynomial is output on the SDO pin as part of the 32-bit cycle.

Table 4. Error Checking Serial Interface Access Cycle

BIT FIELD DESCRIPTION
31 RW Identifies the communication as a read or write command to the addressed register. R/W = 0 sets a write operation. R/W = 1 sets a read operation.
30 CRC-ERROR Reserved bit. Set to zero.
29:28 Reserved Reserved bits. Must be filled with zeros.
27:24 A[3:0] Register address. Specifies the register to be accessed during the read or write operation.
23:8 DI[15:0] Data cycle bits. If a write command, the data cycle bits are the values to be written to the register with address A[3:0]. If a read command, the data cycle bits are don’t care values.
7:0 CRC 8-bit CRC polynomial.

The DACx0504 decodes the 32-bit access cycle to compute the CRC remainder on CS rising edges. If no error exists, the CRC remainder is zero and data are accepted by the device.

A write operation failing the CRC check causes the data to be ignored by the device. After the write command, a second access cycle can be issued to determine the error checking result (CRC-ERROR bit) on the SDO pin, as shown in Table 5. Additionally, by setting ALM-EN = 1 and ALM-SEL = 0 in the CONFIG register, the SDO/ALARM pin is configured as a CRC alarm pin.

Table 5. Write Operation Error Checking Cycle

BIT FIELD DESCRIPTION
31 RW Echo RW from previous access cycle (RW = 0).
30 CRC-ERROR Returns a 1 when a CRC error is detected, 0 otherwise.
29:28 Reserved Echo bits 29:28 from previous access cycle (all zeros).
27:24 A[3:0] Echo address from previous access cycle.
23:8 DO[15:0] Echo data from previous access cycle.
7:0 CRC Calculated CRC value of bits 31:8.

A read operation must be followed by a second access cycle to get the requested data on the SDO pin. The error check result (CRC-ERROR bit) from the read command is output on the SDO pin, as shown in Table 6. As in the case of a write operation failing the CRC check, the SDO/ALARM pin if configured as a CRC alarm pin can be used to indicate a read command CRC failure.

Table 6. Read Operation Error Checking Cycle

BIT FIELD DESCRIPTION
31 RW Echo RW from previous access cycle (RW = 1).
30 CRC-ERROR Returns a 1 when a CRC error is detected, 0 otherwise.
29:28 Reserved Echo bits 29:28 from previous access cycle (all zeros).
27:24 A[3:0] Echo address from previous access cycle.
23:8 DO[15:0] Readback data requested on previous access cycle.
7:0 CRC Calculated CRC value of bits 31:8.