SLUSB18A JUNE   2012  – August 2016 TPS2511

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Switching Characteristics
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Overcurrent Protection
      2. 7.3.2 Current Limit Threshold
      3. 7.3.3 Current-Sensing Report (CS)
      4. 7.3.4 Undervoltage Lockout (UVLO) and Enable (EN)
      5. 7.3.5 Soft Start, Reverse Blocking, and Discharge Output
      6. 7.3.6 Thermal Sense
      7. 7.3.7 VBUS Voltage Drop Compensation
      8. 7.3.8 Divide Mode Selection of 5-W and 10-W USB Chargers
    4. 7.4 Device Functional Modes
      1. 7.4.1 Dedicated Charging Port (DCP)
        1. 7.4.1.1 Short the D+ Line to the D- Line
        2. 7.4.1.2 Divider1 (DCP Applying 2 V on D+ Line and 2.7 V on D- Line) or Divider2 (DCP Applying 2.7 V on D+ Line and 2 V on D- Line)
        3. 7.4.1.3 Applying 1.2 V to the D+ Line and 1.2 V to the D- Line
      2. 7.4.2 DCP Auto-Detect
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Input and Output Capacitance
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

8.1 Application Information

The TPS2511 is a USB-dedicated charging-port controller and power switch with cable compensation. It is typically used for wall adapter or power bank as a USB charging controller and overcurrent protector.

8.2 Typical Application

TPS2511 v12098_lusb18.gif Figure 23. Test Circuit for System Operation

8.2.1 Design Requirements

For this design example, request IOS; Minimum must exceed 2100 mA.

When choosing the power switch, TI recommends following these general steps:

  1. Determine the voltage of the power rail, 3.3 V or 5 V, and then choose the operation range of power switch can cove power rail.
  2. Determine the normal operation current; for example, the maximum allowable current drawn by portable equipment for USB 2.0 port is 500 mA, so the normal operation current is 500 mA and the minimum current limit of power switch must exceed 500 mA to avoid false trigger during normal operation.
  3. Determine the maximum allowable current provided by up-stream power, and then decide the maximum current limit of power switch that must lower it to ensure power switch can protect the up-stream power when overload is encountered at the output of power switch.

NOTE

Choosing power switch with tighter current limit tolerance can loosen the up-stream power supply design.

8.2.2 Detailed Design Procedure

The user-programmable RILIM resistor on the ILIMIT_SET pin sets the current limit. The TPS2511 uses an internal regulation loop to provide a regulated voltage on the ILIM_SET pin. The current limiting threshold is proportional to the current sourced out of the ILIM_SET pin. The recommended 1% resistor range for RILIM is from 16.9 kΩ to 750 kΩ to ensure stability of the internal regulation loop, although not exceeding 210 kΩ results in a better accuracy. Many applications require that the minimum current limit remain above a certain current level or that the maximum current limit remain below a certain current level, so it is important to consider the tolerance of the overcurrent threshold when selecting a value for RILIM. Equation 6 and Equation 7 calculate the resulting overcurrent thresholds for a given external resistor value (RILIM). The traces routing the RILIM resistor to the TPS2511 must be as short as possible to reduce parasitic effects on the current limit accuracy. The equations along with Figure 24 and Figure 25 can be used to estimate the minimum and maximum variation of the current limit threshold for a predefined resistor value. This variation disregards the inaccuracy of the resistor itself.

Equation 6. TPS2511 EQ2_ios_lusb18.gif

where

  • IOS_MIN is in mA
  • RILIM is in kΩ

xxxxxx

Equation 7. TPS2511 EQ3_ios_lusb18.gif

where

  • IOS_MAX is in mA
  • RILIM is in kΩ
TPS2511 ss_RILIM_lusb18.gif
Figure 24. Current Limit Threshold vs Current Limit Resistance
TPS2511 ss2_RILIM_lusb18.gif
Figure 25. Current Limit Threshold vs Current Limit Resistance

For this example design, as shown in Equation 8, IOS_MIN = 2100 mA.

Equation 8. TPS2511 EQ4_ios_lusb18.gif
Equation 9. TPS2511 EQ5_Rilim_lusb18.gif

Including resistor tolerance, target nominal resistance value given by Equation 10.

Equation 10. TPS2511 EQ6_Rilim_lusb18.gif

Choose Equation 11.

Equation 11. RILIM = 22 kΩ

8.2.2.1 Input and Output Capacitance

Input and output capacitance improves the performance of the device; the actual capacitance must be optimized for the particular application. For all applications, TI recommends placing a 0.1-µF or greater ceramic bypass capacitor between IN and GND, as close to the device as possible for local noise decoupling. This precaution reduces ringing on the input due to power-supply transients. Additional input capacitance may be needed on the input to reduce voltage undershoot from exceeding the UVLO of other load share one power rail with TPS2511 or overshoot from exceeding the absolute-maximum voltage of the device during heavy transient conditions. This is especially important during bench testing when long, inductive cables are used to connect the evaluation board to the bench power supply.

TI recommends placing at least a 22-µF ceramic capacitor or higher-value electrolytic capacitor on the output pin when large transient currents are expected on the output to reduce the undershoot, which is caused by the inductance of the output power bus just after a short has occurred and the TPS2511 has abruptly reduced OUT current. Energy stored in the inductance drives the OUT voltage down and potentially negative as it discharges.

8.2.3 Application Curves

TPS2511 inrush_cur_lusb18.gif Figure 26. Inrush Current With Different Capacitance Load
TPS2511 enable_lusb18.gif Figure 28. Enable into 1-Ω Load
TPS2511 load_appl_lusb18.gif Figure 30. 1-Ω Load Applied
TPS2511 sensing_rep_lusb18.gif Figure 32. Output Current-Sensing Report
TPS2511 enable_183_lusb18.gif Figure 27. Enable into 1.83-Ω Load
TPS2511 enable_short_lusb18.gif Figure 29. Enable into Short
TPS2511 hiccup_mode_lusb18.gif Figure 31. Hiccup Mode While Enabled into 1-Ω Load