JAJSBF8B June   2011  – April 2018 TPS54478

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     効率
  4. 4 改訂履歴
  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 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  Fixed Frequency PWM Control
      2. 7.3.2  Slope Compensation and Output Current
      3. 7.3.3  Bootstrap Voltage (BOOT) and Low Dropout Operation
      4. 7.3.4  Error Amplifier
      5. 7.3.5  Voltage Reference
      6. 7.3.6  Adjusting the Output Voltage
      7. 7.3.7  Enable and Adjusting Undervoltage Lockout
      8. 7.3.8  Slow Start / Tracking Pin
      9. 7.3.9  Constant Switching Frequency and Timing Resistor (RT/CLK Pin)
      10. 7.3.10 Overcurrent Protection
      11. 7.3.11 START-UP into Prebiased Output
      12. 7.3.12 Synchronize Using the RT/CLK Pin
      13. 7.3.13 Power Good (PWRGD Pin)
      14. 7.3.14 Overvoltage Transient Protection
      15. 7.3.15 Thermal Shutdown
      16. 7.3.16 Small Signal Model for Loop Response
      17. 7.3.17 Simple Small Signal Model for Peak Current Mode Control
      18. 7.3.18 Small Signal Model for Frequency Compensation
    4. 7.4 Device Functional Modes
      1. 7.4.1 PWM Operation
      2. 7.4.2 Standby Operation
    5. 7.5 Programming
      1. 7.5.1 Sequencing
  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 Selecting the Switching Frequency
        2. 8.2.2.2 Output Inductor Selection
        3. 8.2.2.3 Output Capacitor
        4. 8.2.2.4 Input Capacitor
        5. 8.2.2.5 Slow Start Capacitor
        6. 8.2.2.6 Bootstrap Capacitor Selection
        7. 8.2.2.7 Output Voltage and Feedback Resistors Selection
        8. 8.2.2.8 Compensation
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Power Dissipation Estimate
  11. 11デバイスおよびドキュメントのサポート
    1. 11.1 デバイス・サポート
      1. 11.1.1 デベロッパー・ネットワークの製品に関する免責事項
      2. 11.1.2 WEBENCH®ツールによるカスタム設計
    2. 11.2 ドキュメントのサポート
      1. 11.2.1 関連資料
    3. 11.3 ドキュメントの更新通知を受け取る方法
    4. 11.4 コミュニティ・リソース
    5. 11.5 商標
    6. 11.6 静電気放電に関する注意事項
    7. 11.7 Glossary
  12. 12メカニカル、パッケージ、および注文情報

5 Pin Configuration and Functions

RTE Package
16-Pin WQFN
Top View
TPS54478 po_lvsas2.gif

Pin Functions

PIN I/O DESCRIPTION
NAME NO.
AGND 5 — Analog Ground should be electrically connected to GND close to the device.
BOOT 13 O A bootstrap capacitor is required between BOOT and PH. If the voltage on this capacitor is below the minimum required by the BOOT UVLO, the output is forced to switch off until the capacitor is refreshed.
COMP 7 I/O Error amplifier output, and input to the output switch current comparator. Connect frequency compensation components to this pin.
EN 15 I Enable pin, internal pull-up current source. Pull below 1.21 V to disable. Float to enable. Can be used to set the on/off threshold (adjust UVLO) with two additional resistors.
GND 3, 4 — Power Ground. This pin should be electrically connected directly to the power pad under the IC.
PH 10, 11, 12 O The source of the internal high side power MOSFET, and drain of the internal low side (synchronous) rectifier MOSFET.
PWRGD 14 O An open drain output; asserts low if output voltage is low due to thermal shutdown, overcurrent, over/under-voltage or EN shut down.
RT/CLK 8 I Resistor Timing or External Clock input pin.
SS/TR 9 I Slow start and tracking. An external capacitor connected to this pin sets the output voltage rise time. The SS provides higer charge current when SS is below 0.15V, resulting in two slopes of the SS voltage.
This pin can also be used for tracking.
Thermal Pad 17 — GND pin should be connected to the exposed thermal pad for proper operation. This thermal pad should be connected to any internal PCB ground plane using multiple vias for good thermal performance.
VIN 1, 2, 16 I Input supply voltage, 2.95 V to 6 V.
VSENSE 6 I Inverting node of the transconductance (gm) error amplifier.