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

3.3 No Capability Mismatch and Auto Disable Sink Upon Capability Mismatch

Changed fields from the default values for this example:

  • AUTO_NEGOTIATE_SINK.ANSinkCapMismatchPower = 240d (60W)
  • AUTO_NEGOTIATE_SINK.AutoDisableSinkUponCapabilityMismatch = Varied
  • AUTO_NEGOTIATE_SINK.NoCapabilityMismatch = Varied
Table 3-1 Capability Mismatch Fields Effects on the Sink Path
NoCapabilityMismatch AutoDisableSinkUponCapabilityMismatch Sink Path Effects
0 0 Request PDO asserts Capability Mismatch but sink path is still enabled regardless of ANSinkCapMismatchPower.
0 0 Request PDO asserts Capability Mismatch and sink path disabled when PDO Power < ANSinkCapMismatchPower
1 0 Request PDO does NOT assert Capability Mismatch. AutoDisableSinkUponCapabilityMismatch ignored
1 1 Request PDO does NOT assert Capability Mismatch. AutoDisableSinkUponCapabilityMismatch ignored
If the system requires a minimum of power from USB-PD, then make sure to set the AUTO_NEGOTIATE_SINK.ANSinkCapMismatchPower to the minimum value of the system. Make sure the AUTO_NEGOTIATE_SINK.NoCapabilityMismatch is = 0 to keep Capabiltiy Mismatch assertion behavior. Finally set AUTO_NEGOTIATE_SINK.AutoDisableSinkUponCapabilityMismatch = 1 to allow PD to disable sink path automatically if system requirements are not met.

  • AUTO_NEGOTIATE_SINK.ANSinkCapMismatchPower = 240d (60W)
  • AUTO_NEGOTIATE_SINK.NoCapabilityMismatch = 0
  • AUTO_NEGOTIATE_SINK.AutoDisableSinkUponCapabilityMismatch = 1
Capability Mismatch is asserted in the Request Message causing PD device to not enable the PPHV_EN Figure 3-3 Capability Mismatch is asserted in the Request Message causing PD device to not enable the PPHV_EN
Request Data Object from the PD Device to the PD Source Figure 3-4 Request Data Object from the PD Device to the PD Source.

The Capability mismatch flag is set here which causes the PD Device to NOT enable the PPHV_EN above.

If the system can still be powered at less than the AUTO_NEGOTIATE_SINK.ANSinkCapMismatchPower value, then set AUTO_NEGOTIATE_SINK.NoCapabilityMismatch to 0 or 1 depending on if system needs to assert Capability Mismatch in the Request PDO. And AUTO_NEGOTIATE_SINK.AutoDisableSinkUponCapabilityMismatch to 0.

  • AUTO_NEGOTIATE_SINK.ANSinkCapMismatchPower = 240d (60W)
  • AUTO_NEGOTIATE_SINK.NoCapabilityMismatch = 0
  • AUTO_NEGOTIATE_SINK.AutoDisableSinkUponCapabilityMismatch = 0
Capability Mismatch is asserted in the Request Message but PD device still enables PPHV_EN Figure 3-5 Capability Mismatch is asserted in the Request Message but PD device still enables PPHV_EN
Request Data Object from the PD Device to the PD Source Figure 3-6 Request Data Object from the PD Device to the PD Source
  • AUTO_NEGOTIATE_SINK.ANSinkCapMismatchPower = 240d (60W)
  • AUTO_NEGOTIATE_SINK.NoCapabilityMismatch = 1
  • AUTO_NEGOTIATE_SINK.AutoDisableSinkUponCapabilityMismatch = 0
Capability Mismatch is not asserted in the Request Message Figure 3-7 Capability Mismatch is not asserted in the Request Message
Request Data Object from the PD Device to the PD Source Figure 3-8 Request Data Object from the PD Device to the PD Source