SLASES7A July   2019  – December 2019 DAC43401 , DAC53401

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Functional Block Diagram
      2.      Power-Supply Control With the DACx3401
  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  Timing Requirements: I2CTM Standard mode
    7. 7.7  Timing Requirements: I2CTM Fast mode
    8. 7.8  Timing Requirements: I2CTM Fast+ mode
    9. 7.9  Typical Characteristics: VDD = 1.8 V (Reference = VDD) or VDD = 2 V (Internal Reference)
    10. 7.10 Typical Characteristics: VDD = 5.5 V (Reference = VDD) or VDD = 5 V (Internal Reference)
    11. 7.11 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) Architecture
        1. 8.3.1.1 Reference Selection and DAC Transfer Function
          1. 8.3.1.1.1 Power Supply as Reference
          2. 8.3.1.1.2 Internal Reference
      2. 8.3.2 DAC Update
        1. 8.3.2.1 DAC Update Busy
      3. 8.3.3 Nonvolatile Memory (EEPROM or NVM)
        1. 8.3.3.1 NVM Cyclic Redundancy Check
        2. 8.3.3.2 NVM_CRC_ALARM_USER Bit
        3. 8.3.3.3 NVM_CRC_ALARM_INTERNAL Bit
      4. 8.3.4 Programmable Slew Rate
      5. 8.3.5 Power-on-Reset (POR)
      6. 8.3.6 Software Reset
      7. 8.3.7 Device Lock Feature
      8. 8.3.8 PMBus Compatibility
    4. 8.4 Device Functional Modes
      1. 8.4.1 Power Down Mode
      2. 8.4.2 Continuous Waveform Generation (CWG) Mode
      3. 8.4.3 PMBus Compatibility Mode
      4. 8.4.4 Medical Alarm Generation Mode
        1. 8.4.4.1 Low-Priority Alarm
        2. 8.4.4.2 Medium-Priority Alarm
        3. 8.4.4.3 High-Priority Alarm
        4. 8.4.4.4 Interburst Time
        5. 8.4.4.5 Pulse Off Time
        6. 8.4.4.6 Pulse On Time
    5. 8.5 Programming
      1. 8.5.1 F/S Mode Protocol
      2. 8.5.2 DACx3401 I2C Update Sequence
      3. 8.5.3 Address Byte
      4. 8.5.4 Command Byte
      5. 8.5.5 I2C Read Sequence
    6. 8.6 Register Map
      1. 8.6.1  STATUS Register (address = D0h) (reset = 000Ch or 0014h)
        1. Table 18. STATUS Register Field Descriptions
      2. 8.6.2  GENERAL_CONFIG Register (address = D1h) (reset = 01F0h)
        1. Table 19. GENERAL_CONFIG Register Field Descriptions
      3. 8.6.3  MED_ALARM_CONFIG Register (address = D2h) (reset = 0000h)
        1. Table 20. MED_ALARM_CONFIG Register Field Descriptions
      4. 8.6.4  TRIGGER Register (address = D3h) (reset = 0008h)
        1. Table 21. TRIGGER Register Field Descriptions
      5. 8.6.5  DAC_DATA Register (address = 21h) (reset = 0000h)
        1. Table 22. DAC_DATA Register Field Descriptions
      6. 8.6.6  DAC_MARGIN_HIGH Register (address = 25h) (reset = 0000h)
        1. Table 23. DAC_MARGIN_HIGH Register Field Descriptions
      7. 8.6.7  DAC_MARGIN_LOW Register (address = 26h) (reset = 0000h)
        1. Table 24. DAC_MARGIN_LOW Register Field Descriptions
      8. 8.6.8  PMBUS_OPERATION Register (address = 01h) (reset = 0000h)
        1. Table 25. PMBUS_OPERATION Register Field Descriptions
      9. 8.6.9  PMBUS_STATUS_BYTE Register (address = 78h) (reset = 0000h)
        1. Table 26. PMBUS_STATUS_BYTE Register Field Descriptions
      10. 8.6.10 PMBUS_VERSION Register (address = 98h) (reset = 2200h)
        1. Table 27. PMBUS_VERSION Register Field Descriptions
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Programmable LED Biasing
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Power-Supply Margining
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
      3. 9.2.3 Medical Alarm Generation
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
        3. 9.2.3.3 Application Curves
  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 Support 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

9.2.2.2 Detailed Design Procedure

The DACx3401 features a Hi-Z power-down mode that is set by default at power-up, unless the device is programmed otherwise using the NVM. When the DAC output is at Hi-Z, the current through R3 is zero and the SMPS is set at the nominal output voltage of 3.3 V. To have the same nominal condition when the DAC powers up, bring up the device at the same output as VFB (that is 0.6 V). This configuration makes sure there is no current through R3 even at power-up. Calculate R1 as (VOUT – VFB) / 100 µA = 27 kΩ.

To achieve ±10% margin-high and margin-low conditions, the DAC must sink or source additional current through R1. Calculate the current from the DAC (IMARGIN) using Equation 7 as 12 µA.

Equation 7. DAC53401 DAC43401 dacx3401-ps-margining-current-eq.gif

where

  • IMARGIN is the margin current sourced or sinked from the DAC.
  • MARGIN is the percentage margin value divided by 100.
  • INOMINAL is the nominal current through R1 and R2.

In order to calculate the value of R3, first decide the DAC output range, and make sure to avoid the codes near zero-scale and full-scale for safe operation in the linear region. A DAC output of 20 mV is a safe consideration as the minimum output, and (1.8 V – 0.6 V – 20 mV = 1.18 V) as the maximum output. When the DAC output is at 20 mV, the power supply goes to margin high, and when the DAC output is at 1.18 V, the power supply goes to margin low. Calculate the value of R3 usingEquation 8 as 48.3 kΩ. Choose a standard resistor value and adjust the DAC outputs. Choosing R3 = 47 kΩ makes the DAC margin high code as 1.164 V and the DAC margin low code as 36 mV.

Equation 8. DAC53401 DAC43401 dac3401-ps-margining-r3-eq.gif

The DACx3401 have a slew rate feature that is used to toggle between margin high, margin low, and nominal outputs with a defined slew rate. See the GENERAL_CONFIG register description for the slew rate setting details.

NOTE

The MARGIN HIGH register value in DACx3401 results in the MARGIN LOW value at the power supply output. Similarly, the MARGIN LOW register value in DACx3401 results in the MARGIN HIGH value at the power-supply output.

The pseudocode for getting started with a power-supply control application is as follows:

//SYNTAX: WRITE <REGISTER NAME (Hex code)>, <MSB DATA>, <LSB DATA>
//Write DAC code (12-bit aligned) for nominal output
//For a 1.8-V output range, the 10-bit hex code for 0.6 V is 0x0155. With 12-bit alignment, it becomes 0x0554
WRITE DAC_DATA(0x21), 0x05, 0x54
//Write DAC code (12-bit aligned) for margin-low output at the power supply
//For a 1.8-V output range, the 10-bit hex code for 1.164 V is 0x0296. With 12-bit alignment, it becomes 0x0A58
WRITE DAC_MARGIN_HIGH(0x25), 0x0A, 0x58
//Write DAC code (12-bit aligned) for margin-high output at the power supply
//For a 1.8-V output range, the 10-bit hex code for 36 mV is 0x14. With 12-bit alignment, it becomes 0x50
WRITE DAC_MARGIN_LOW(0x26), 0x00, 0x50
//Power-up the device with enable internal reference with 1.5x output span. This will output the nominal voltage (0.6 V)
//CODE_STEP: 2 LSB, SLEW_RATE: 25.6 µs
WRITE GENERAL_CONFIG(0xD1), 0x12, 0x14
//Trigger margin-low output at the power supply
WRITE TRIGGER(0xD3), 0x00, 0x80
//Trigger margin-high output at the power supply
WRITE TRIGGER(0xD3), 0x00, 0x40
//Write back DAC code (12-bit aligned) for nominal output
WRITE DAC_DATA(0x21), 0x05, 0x54