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

6.4.2 AUTO_NEGOTIATE_SINK Usage Example 2

When attached to a 36W source the PD controller has RX_SOURCE_CAPS:

  • PDO1: 5V at 3A
  • PDO2: 9V at 3A
  • PDO3: 15V at 2.4A

The PD controller has TX_SINK_CAPS set as:

  • PDO1: 5V at 0.1A (fixed)
  • PDO2: 20V at 3A (fixed)

The PD controller has AUTO_NEGOTIATE_SINK set as:

  • AUTO_NEGOTIATE_SINK = 0
  • AUTO_NEGOTIATE_SINK.AutoComputeSinkMinPower = 1
  • AUTO_NEGOTIATE_SINK.AutoComputeSinkMinVoltage = 0
  • AUTO_NEGOTIATE_SINK.ANMinVoltage = 20V
  • AUTO_NEGOTIATE_SINK.AutoComputeSinkMaxVoltage = 1
  • AUTO_NEGOTIATE_SINK.NoCapabilityMismatch = x (see table below)
  • AUTO_NEGOTIATE_SINK.ANRDOPriority = 0

The settings give the results in the table below. Note that ANMaxVoltage computed as 20V, but this does not affect the result. Because the ANMinVoltage was set to 20V, and the source is not offering 20V none of the source PDOs fulfill the sink requirements. Even though ANSinkCapMismatchPower=0 in this example, because the voltages offered are insufficient, the capability mismatch bit can still be set.

Table 6-3 AUTO_NEGOTIATE_SINK Usage Example 2
AUTO_NEGOTIATE_SINK ACTIVE_CONTRACT_RDO
NoCapabilityMismatch OperatingX MinMaxOperatingX ObjectPosition Capability Mismatch
0 3.0A 3.0A 1 1
1 3.0A 3.0A 1 0