JAJS012J October   2004  – November 2018 TPS75003

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     Device Images
      1.      代表的なアプリケーションの回路図
  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
      1. 6.6.1 Buck Converter
      2. 6.6.2 LDO Converter
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Operation (Buck Controllers)
      2. 7.3.2  Enable (Buck Controllers)
      3. 7.3.3  UVLO (Buck Controllers)
      4. 7.3.4  Current Limit (Buck Controllers)
      5. 7.3.5  Short-Circuit Protection (Buck Controllers)
      6. 7.3.6  Soft-Start (Buck Controllers)
      7. 7.3.7  LDO Operation
      8. 7.3.8  Internal Current Limit (LDO)
      9. 7.3.9  Enable Pin (LDO)
      10. 7.3.10 Dropout Voltage (LDO)
      11. 7.3.11 Transient Response (LDO)
      12. 7.3.12 Thermal Protection (LDO)
      13. 7.3.13 Power Dissipation (LDO)
  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 CIN1, CIN2 Selection (Buck Controllers)
        2. 8.2.2.2  Inductor Value Selection (Buck Controllers)
        3. 8.2.2.3  External PMOS Transistor Selection (Buck Controllers)
        4. 8.2.2.4  Diode Selection (Buck Controllers)
        5. 8.2.2.5  Output Capacitor Selection (Buck Controllers)
        6. 8.2.2.6  Output Voltage Ripple Effect on VOUT (Buck Controllers)
        7. 8.2.2.7  Soft-Start Capacitor Selection (Buck Controllers)
        8. 8.2.2.8  Output Voltage Setting Selection (Buck Controllers)
        9. 8.2.2.9  Input Capacitor Selection (LDO)
        10. 8.2.2.10 Output Capacitor Selection (LDO)
        11. 8.2.2.11 Soft-Start Capacitor Selection (LDO)
        12. 8.2.2.12 Setting Output Voltage (LDO)
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 PCB Layout Considerations
    2. 10.2 Layout Example
  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 開発サポート
    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

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

7.3.6 Soft-Start (Buck Controllers)

The buck controllers each have independent soft-start capability to limit inrush during start-up and to meet timing requirements of the Xilinx Spartan-3 FPGA. Limiting inrush current by using soft-start, or by staggering the turnon of power rails, also guards against voltage drops at the input source due to its output impedance. Refer to the soft-start circuitry shown in Figure 16 and the soft-start timing diagram shown in Figure 17. The BUCK1 controller is discussed in this section; it is identical to BUCK2. Note that pins SS1 and SS2 are very high-impedance and cannot be probed using a typical oscilloscope setup. When input voltage is applied at IN1 and EN1 is driven low, any charge on the SS pin is discharged by an on-chip pulldown transistor. When EN1 is driven high, an on-chip current source starts charging the external soft-start capacitor CSS1. The voltage on the capacitor is compared to the voltage across the current sense resistor R1 to determine if an overcurrent condition exists. If the voltage drop across the sense resistor becomes greater than the reference voltage, then the external PMOS is shut off for the minimum off-time. This implementation provides a cycle-by-cycle current limit and lets the user configure the soft-start time over a wide range for most applications. For detailed information on selecting CSS1 and CSS2, see the Soft-Start Capacitor Selection (Buck Controllers) section.

TPS75003 tc02_bvs052.gifFigure 16. Soft-Start Circuitry
TPS75003 tc03_bvs052.gifFigure 17. Soft-Start Timing Diagram