SLVSCE8C January   2015  – September 2018 TPS7B7701-Q1 , TPS7B7702-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Application Diagram
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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  Fault Detection and Protection
      2. 7.3.2  Short-Circuit and Overcurrent Protection
      3. 7.3.3  Short-to-Battery and Reverse Current Detection
      4. 7.3.4  Thermal Shutdown
      5. 7.3.5  Integrated Reverse-Polarity Protection
      6. 7.3.6  Integrated Inductive Clamp
      7. 7.3.7  Undervoltage Lockout
      8. 7.3.8  Enable (EN, EN1, and EN2)
      9. 7.3.9  Internal Voltage Regulator (VCC)
      10. 7.3.10 Current Sense Multiplexing
      11. 7.3.11 Adjustable Output Voltage (FB, FB1, and FB2)
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation With IN < 4.5 V
      2. 7.4.2 Operation With EN Control
  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 Capacitor
        2. 8.2.2.2 Output Capacitor
        3. 8.2.2.3 Current Sense Resistor Selection
        4. 8.2.2.4 Current-Limit Resistor Selection
      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 Related Links
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Community Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • PWP|16
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.2.2.3 Current Sense Resistor Selection

The current-sense outputs, SENSEx (SENSE, SENSE1, and SENSE2), are proportional to the output current at the OUT, OUT1, and OUT2 pins with a factor of 1/198. An output resistor, R(SENSE), must be connected between the SENSEx pin and ground to generate a current sense voltage to be sampled by ADC. Use Equation 2 to calculate the voltage at SENSEx pin (V(SENSEx)).

Equation 2. TPS7B7701-Q1 TPS7B7702-Q1 eq_04_slvsce8.gif

where

  • TPS7B7701-Q1 TPS7B7702-Q1 eq_03_slvsce8.gif

For this example, select 1.5 kΩ as a value for R(SENSEx). Do not consider the resistor and current-sense accuracy.

For a load current of 198 mA, use Equation 3 to calculate the value of V(SENSEx).

Equation 3. TPS7B7701-Q1 TPS7B7702-Q1 eq_05_slvsce8.gif

To avoid any overlap between normal operation and current-limit or short-to-ground phase, using Equation 4 to select the value of the SENSE resistor is recommended.

Equation 4. TPS7B7701-Q1 TPS7B7702-Q1 eq_06_slvsce8.gif

where

  • 198 is the output current to current-sense ratio
  • 2.4 V is the minimum possible voltage at the SENSEx pin under a short-circuit fault case
  • IOmax is the maximum possible output current under normal operation

To stabilize the current-sense loop, connecting a 1-µF ceramic capacitor at the SENSE, SENSE1, or SENSE2 pin is required. Table 4 lists the current sense accuracy across temperature.

Table 4. Current Sense Accuracy

OUTPUT CURRENT CURRENT SENSE ACCURACY
5 mA to 10 mA 20%
10 mA to 50 mA 10%
50 mA to 100 mA 5%
100 mA to 300 mA 3%