ZHCSHC3B january   2018  – june 2023 TPS61280D , TPS61280E , TPS61281D

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  5. 4 Revision History
  6. 5 说明（续）
  7. 6 Device Comparison Table
  8. 7 Pin Configuration and Functions
  9. 8 Specifications
    1. 8.1 Absolute Maximum Ratings
    2. 8.2 ESD Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Information
    5. 8.5 Electrical Characteristics
    6. 8.6 I2C Interface Timing Characteristics #GUID-BD85FD7C-B9AF-4F5D-9DFF-CD61365A592A/SLVS5401494
    7. 8.7 I2C Timing Diagrams
    8. 8.8 Typical Characteristics
  10. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Voltage Scaling Management (VSEL)
      2. 9.3.2 Spread Spectrum, PWM Frequency Dithering
    4. 9.4 Device Functional Modes
      1. 9.4.1 Power-Save Mode
      2. 9.4.2 Pass-Through Mode
      3. 9.4.3 Mode Selection
      4. 9.4.4 Current Limit Operation
      5. 9.4.5 Start-Up and Shutdown Mode
      6. 9.4.6 Undervoltage Lockout
      7. 9.4.7 Thermal Shutdown
      8. 9.4.8 Fault State and Power-Good
    5. 9.5 Programming
      1. 9.5.1 Serial Interface Description (TPS61280D/E)
      2. 9.5.2 Standard-, Fast-, Fast-Mode Plus Protocol
      3. 9.5.3 HS-Mode Protocol
      4. 9.5.4 TPS6128xD/E I2C Update Sequence
    6. 9.6 Register Maps
      1. 9.6.1  Slave Address Byte
      2. 9.6.2  Register Address Byte
      3. 9.6.3  I2C Registers, E2PROM, Write Protect
      4. 9.6.4  E2PROM Configuration Parameters
      5. 9.6.5  CONFIG Register [reset = 0x01]
      6. 9.6.6  VOUTFLOORSET Register [reset = 0x02]
      7. 9.6.7  VOUTROOFSET Register [reset = 0x03]
      8. 9.6.8  ILIMSET Register [reset = 0x04]
      9. 9.6.9  Status Register [reset = 0x05]
      10. 9.6.10 E2PROMCTRL Register [reset = 0xFF]
  11. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 TPS61281D with 2.5V-4.35 VIN, 1500 mA Output Current (TPS61280D with default I2C Configuration)
        1. 10.2.1.1 Design Requirement
        2. 10.2.1.2 Detailed Design Parameters
          1. 10.2.1.2.1 Inductor Selection
          2. 10.2.1.2.2 Output Capacitor
          3. 10.2.1.2.3 Input Capacitor
          4. 10.2.1.2.4 Checking Loop Stability
        3. 10.2.1.3 Application Performance Curves
      2. 10.2.2 TPS61282D with 2.5V-4.35 VIN, 2000 mA Output Current (TPS61280D with I2C Programmable)
        1. 10.2.2.1 Design Requirements
        2. 10.2.2.2 Detailed Design Procedures
        3. 10.2.2.3 Application Performance Curves
  12. 11Power Supply Recommendations
  13. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
    3. 12.3 Thermal Information
  14. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 第三方产品免责声明
    2. 13.2 接收文档更新通知
    3. 13.3 支持资源
    4. 13.4 Trademarks
    5. 13.5 静电放电警告
    6. 13.6 术语表
  15. 14Mechanical, Packaging, and Orderable Information
    1. 14.1 Package Summary

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9.4.2 Pass-Through Mode

The TPS6128xD/E contains an internal switch for bypassing the dc/dc boost converter during pass-through mode. When the input voltage is larger than the preset output voltage, the converter seamlessly transitions into 0% duty cycle operation and the bypass FET is fully enhanced. Entry in pass-through mode is triggered by condition where VOUT >(1+2%)* VOUT_NORM and no switching has occurred during past 8µs.

In this mode of operation, the load (2G RF PA for instance) is directly supplied from the battery for maximum RF output power, highest efficiency and lowest possible input-to-output voltage difference. The device consumes only a standby current of 15µA (typ). In pass-through mode, the device is short-circuit protected by a very fast current limit detection scheme.

During this operation, the output voltage follows the input voltage and will not fall below the programmed output voltage threshold as the input voltage decreases. The output voltage drop during pass-through mode depends on the load current and input voltage, the resulting output voltage is calculated as:

Equation 4. GUID-7C265430-AEDD-4671-B891-703A20D28CF2-low.gif

Conversely, the efficiency in pass-through mode is defined as:

Equation 5. GUID-7E5EBB90-D890-4A83-9129-36B87A79ACB3-low.gif
  • in which RDSON(BP) is the typical on-resistance of the bypass FET
GUID-4F9C085E-7AC9-4415-9CF5-8376EBCD191E-low.pngFigure 9-4 DC Output Voltage vs. Input Voltage

Pass-through mode exit is triggered when the output voltage reaches the pre-defined threshold (that is, 3.4V).

During pass-through mode, the TPS6128xD/E device is short-circuit protected by a fast current limit detection scheme. If the current in the pass-through FET exceeds approximately 7.3 Amps a fault is declared and the device cycles through a start-up procedure.