SLUSDX7A September   2020  – October 2020 TPS51397A

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 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 PWM Operation and DCAP3 Control
      2. 7.3.2 Soft Start
      3. 7.3.3 Large Duty Operation
      4. 7.3.4 Power Good
      5. 7.3.5 Overcurrent Protection and Undervoltage Protection
      6. 7.3.6 Overvoltage Protection
      7. 7.3.7 UVLO Protection
      8. 7.3.8 Output Voltage Discharge
      9. 7.3.9 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Light Load Operation
      2. 7.4.2 Advanced Eco-mode Control
      3. 7.4.3 Out-of-Audio
      4. 7.4.4 Mode Selection
      5. 7.4.5 Standby Operation
  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 External Component Selection
          1. 8.2.2.1.1 Output Voltage Set Point
          2. 8.2.2.1.2 MODE Selection
          3. 8.2.2.1.3 Inductor Selection
          4. 8.2.2.1.4 Output Capacitor Selection
          5. 8.2.2.1.5 Input Capacitor 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 Receiving Notification of Documentation Updates
    2. 11.2 Support Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.4.4 Mode Selection

The device detects the voltage on the MODE pin during start-up and latches onto one of the MODE options listed in Table 7-1. The voltage on the MODE pin is recommended to be set by connecting this pin to the center tap of a resistor divider connected between VCC and AGND. A guideline for the top resistor (RM_H) and the bottom resistor (RM_L) as 1% resistors is shown in Table 7-1. It is recommended to choose the resistor to set the voltage at around the middle value of each range. It is important that the voltage for the MODE pin is derived from the VCC rail only since internally this voltage is referenced to detect the MODE option, and not to leave the mode pin floating. The MODE pin setting can be reset only by a VIN power cycling or EN toggle.

Table 7-1 MODE Pin Resistor Settings
VOLTAGE ON MODE RM_H(kΩ) RM_L (kΩ) LIGHT LOAD OPERATION FREQUENCY (kHz)
(0~10%)*VCC 330 15 Eco-mode 500
(10%~20%)*VCC

180

 33 OOA 500
(20%~30%)*VCC 160 51 Eco-mode 800
(30%~50%)*VCC 75 51 OOA 800

Figure 7-1 shows the typical start-up sequence of the device once the enable signal crosses the EN turnon threshold. After the voltage on VCC crosses the rising UVLO threshold, it takes about 500 μs to finish the working mode and frequency selection. The output voltage starts ramping after about 0.2*TSS delay time.

GUID-20200820-CA0I-LLXG-ZQ8S-C7P6692DFNWJ-low.gif Figure 7-1 Power-Up Sequence