SDAA265 April   2026 TPS26750A

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Applicability to other TI USB-PD Controllers
    1. 1.1 USB-PD Sink Introduction
    2. 1.2 Autonegotiate Sink Purpose
    3. 1.3 Definitions
  5. 2Fields Covered
  6. 3Autonegotiate Sink Basics with Examples
    1. 3.1 Auto Neg RDO Priority (ANRDOPriority)
    2. 3.2 Auto Compute Sink Min Power and Auto Neg Sink Min Required Power
    3. 3.3 No Capability Mismatch and Auto Disable Sink Upon Capability Mismatch
    4. 3.4 Auto Compute Sink Min Voltage and Auto Neg Min Voltage
    5. 3.5 Auto Compute Sink Max Voltage & Auto Neg Max Voltage
  7. 4Autonegotiate Sink Basics with EPR Examples
    1. 4.1 Systems Requiring ≥140W
    2. 4.2 Sink Path SPR to EPR Transitions
  8. 5Common Mistakes or Unique System Constraints
    1. 5.1 System Needs More Power but PD Selects Lower Power PDOs
    2. 5.2 System Supports EPR Power but PD Keeps Selecting 20V PDOs
    3. 5.3 Setting the Min Voltage and Max Voltage to the Same Values
  9. 6Advanced Autonegotiate Sink Examples
    1. 6.1 Downgrading to 5V Fixed PDO
    2. 6.2 Autonegotiate Sink With Interrupt Driven EC
    3. 6.3 ANeg: Auto Negotiate Sink Update
    4. 6.4 AUTO_NEGOTIATE_SINK Register
      1. 6.4.1 AUTO_NEGOTIATE_SINK Usage Example 1
      2. 6.4.2 AUTO_NEGOTIATE_SINK Usage Example 2
      3. 6.4.3 AUTO_NEGOTIATE_SINK Usage Example 3
      4. 6.4.4 AUTO_NEGOTIATE_SINK Usage Example 4
  10. 7References

3.5 Auto Compute Sink Max Voltage & Auto Neg Max Voltage

Changed fields from the default values for this example:
  • AUTO_NEGOTIATE_SINK.AutoNegMaxVoltage = 300d (15V)
  • AUTO_NEGOTIATE_SINK.AutoComputeSinkMaxVoltage = Varied

If the system can always handle the largest voltage in SPR (up to 20V) or EPR (up to 48V) then leaving AUTO_NEGOTIATE_SINK.AutoComputeSinkMaxVoltage = 1 is acceptable. This means PD looks at the source PDOs offered and set this value to the maximum voltage value.

If the system requires a specific maximum and cannot exceed the voltage, then setting AUTO_NEGOTIATE_SINK.AutoComputeSinkMaxVoltage = 0 means the AUTO_NEGOTIATE_SINK.AutoNegMaxVoltage is set by configuration or by the EC regardless of the source PDO voltages.

(Show test 4 with PD setting MaxVoltage

  • AUTO_NEGOTIATE_SINK.AutoNegMaxVoltage = 300d (15V)
  • AUTO_NEGOTIATE_SINK.AutoComputeSinkMaxVoltage = 1
PD Device auto computes AUTO_NEGOTIATE_SINK.AutoNegMaxVoltage Figure 3-9 PD Device auto computes AUTO_NEGOTIATE_SINK.AutoNegMaxVoltage
  • AUTO_NEGOTIATE_SINK.AutoNegMaxVoltage = 300d (15V)
  • AUTO_NEGOTIATE_SINK.AutoComputeSinkMaxVoltage = 0
PD Device Always Requesting 15V PDO Figure 3-10 PD Device Always Requesting 15V PDO
USB-PD Capture of the 20V PDO Offered Figure 3-11 USB-PD Capture of the 20V PDO Offered