SLVSCP4B October   2014  – August 2015 TPD3S014 , TPD3S044

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Device Comparison Table
  6. Pin Configuration and Functions
  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: TJ = TA = 25°C
    6. 7.6 Electrical Characteristics: -40°C ≤ TJ ≤ 125°C
    7. 7.7 Typical Characteristics
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Undervoltage Lockout (UVLO)
      2. 8.3.2 Enable
      3. 8.3.3 Internal Charge Pump
      4. 8.3.4 Current Limit
      5. 8.3.5 Output Discharge
      6. 8.3.6 Input and Output Capacitance
    4. 8.4 Device Functional Modes
      1. 8.4.1 Operation With VIN < 4 V (Minimum VIN)
      2. 8.4.2 Operation With EN Control
      3. 8.4.3 Operation of Level 4 IEC61000-4-2 ESD Protection
  9. Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 USB2.0 Application
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Implementing Active Low Logic
        4. 9.2.1.4 Application Curves
      2. 9.2.2 USB3.0 Application
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Examples
    3. 11.3 Power Dissipation and Junction Temperature
  12. 12Device and Documentation Support
    1. 12.1 Related Links
    2. 12.2 Community Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

11 Layout

11.1 Layout Guidelines

  • The optimum placement is as close to the connector as possible.
    • EMI during an ESD event can couple from the trace being struck to other nearby unprotected traces, resulting in early system failures.
    • The PCB designer needs to minimize the possibility of EMI coupling by keeping any unprotected traces away from the protected traces which are between the TVS and the connector.
  • Route the protected traces as straight as possible.
  • Eliminate any sharp corners on the protected traces between the TVS and the connector by using rounded corners with the largest radii possible.
    • Electric fields tend to build up on corners, increasing EMI coupling.

11.2 Layout Examples

TPD3S014 TPD3S044 TPD3S0x4_Layout2.gifFigure 36. USB2.0 Type A TPD3S0x4 Board Layout
TPD3S014 TPD3S044 TPD3S0x4_USB3_Layout.gifFigure 37. USB3.0 Type A TPD3S044 Board Layout

11.3 Power Dissipation and Junction Temperature

It is good design practice to estimate power dissipation and maximum expected junction temperature of the TPD3S0x4s. The system designer can control choices of the devices proximity to other power dissipating devices and printed circuit board (PCB) design based on these calculations. These have a direct influence on maximum junction temperature. Other factors, such as airflow and maximum ambient temperature, are often determined by system considerations. It is important to remember that these calculations do not include the effects of adjacent heat sources, and enhanced or restricted air flow. Addition of extra PCB copper area around these devices is recommended to reduce the thermal impedance and maintain the junction temperature as low as practical. In particular, connect the GND pin to a large ground plane for the best thermal dissipation. The following PCB layout example Figure 38 was used to determine the RθJA Custom thermal impedances noted in the Thermal Informationtable. It is based on the use of the JEDEC high-k circuit board construction with 4, 1 oz. copper weight layers (2 signal and 2 plane).

TPD3S014 TPD3S044 TPD3S0x4_Layout_with_Dimensions2.gifFigure 38. PCB Layout Example

The following procedure requires iteration because power loss is due to the internal MOSFET I2 × RDS(ON), and RDS(ON) is a function of the junction temperature. As an initial estimate, use the RDS(ON) at 125°C from the Typical Characteristics, and the preferred package thermal resistance for the preferred board construction from the Thermal Information table.

Equation 1. TJ = TA + [(IOUT2 × RDS(ON)) × RθJA]

where

  • IOUT = Rated OUT pin current (A)
  • RDS(ON) = Power switch on-resistance at an assumed TJ (Ω)
  • TA = Maximum ambient temperature (°C)
  • TJ = Maximum junction temperature (°C)
  • RθJA = Thermal resistance (°C/W)

If the calculated TJ is substantially different from the original assumption, estimate a new value of RDS(ON) using the typical characteristic plot and recalculate.

If the resulting TJ is not less than 125°C, try a PCB construction with a lower RθJA. Please find the junction temperature derating curve based on the TI standard reliability duration in Figure 39.

TPD3S014 TPD3S044 D038_TPD3S0x4_Graph_Data.gifFigure 39. Junction Temperature Derating Curve