JAJSH91B April   2019  – January 2020 TPS92613-Q1

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 Timing Requirements
    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 Power Supply
        1. 7.3.1.1 Power-On Reset (POR)
        2. 7.3.1.2 Low-Quiescent-Current
      2. 7.3.2 Constant-Current Driver
      3. 7.3.3 PWM Control
      4. 7.3.4 Supply Control
      5. 7.3.5 Diagnostics and Protection
        1. 7.3.5.1 Open-Circuit Detection
        2. 7.3.5.2 Short-to-GND Detection
        3. 7.3.5.3 Overtemperature Protection
        4. 7.3.5.4 DIAGEN
        5. 7.3.5.5 Low-Dropout Operation
      6. 7.3.6 FAULT Bus Output With One-Fails–All-Fail
      7. 7.3.7 Fault Table
    4. 7.4 Device Functional Modes
      1. 7.4.1 Undervoltage Lockout, V(SUPPLY) < V(POR_rising)
      2. 7.4.2 Normal Operation V(SUPPLY) ≥ 4.5 V
      3. 7.4.3 Low-Voltage Dropout Operation
      4. 7.4.4 Fault Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Single-Channel LED Driver With Diagnostics
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Single-Channel LED Driver With Heat Sharing
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    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 ドキュメントのサポート
      1. 11.1.1 関連資料
    2. 11.2 ドキュメントの更新通知を受け取る方法
    3. 11.3 サポート・リソース
    4. 11.4 商標
    5. 11.5 静電気放電に関する注意事項
    6. 11.6 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

8.2.1.2 Detailed Design Procedure

STEP 1: Determine the current setting resistor, R(SNS) value by using Equation 2.

Equation 2. TPS92613-Q1 eq-rsns-app1-slesvc4.gif

where

  • V(CS_REG) = 98 mV (typical.)
  • I(LED) = 250 mA

STEP 2: Design the threshold voltage for SUPPLY to enable the LED open-circuit diagnostics and calculate the resistor divider value.

LED-string maximum forward voltage = 3 × 2.5 V = 7.5 V. To avoid the open-circuit fault reported in low-dropout operation conditions, additional headroom between SUPPLY and OUT needs to be considered. The TPS92613-Q1 device must disable open-circuit detection when the supply voltage is below LED-string maximum forward voltage plus maximum V(OPEN_th_rising) and maximum V(CS_REG). The voltage divider resistor, R1 and R2 value can be calculated by Equation 3.

Equation 3. TPS92613-Q1 eq-vil-app1-slesvc4.gif

where

  • VIL(DIAGEN) = 1.045 V (minimum)
  • V(OPEN_th_rising) = 335 mV (maximum)
  • V(CS_REG) = 102.5 mV (maximum)
  • R1 = 10 kΩ recommended

The calculated result for R2 is 65.7 kΩ when V(OUT) maximum voltage is 7.5 V.

STEP 3: Thermal analysis for the worst application conditions.

Normally the thermal analysis is necessary for linear LED-driver applications to ensure that the operation junction temperature of TPS92613-Q1 is well managed. The total power consumption on the TPS92613-Q1 itself is one important factor determining operation junction temperature, and it can be calculated by using Equation 4. Based on the worst-case analysis for maximum power consumption on device, consider either optimizing PCB layout for better power dissipation as Layout describes or adding an extra heat-sharing resistor as described in Single-Channel LED Driver With Heat Sharing.

Equation 4. TPS92613-Q1 eq-pmax-app1-slesvc4.gif

where

  • V(CS_REG) = 98 mV (typical)
  • I(Quiescent) = 250 µA (maximum)

In this application, the calculated result for maximum power consumption on the TPS92613-Q1 is 2.55 W at V(SUPPLY) = 16 V and I(LED) = 250 mA conditions.

TI recommends to add capacitors C(SUPPLY) at SUPPLY and C(OUT)at OUT. TI recommends one 1-μF capacitor plus one 100-nF decoupling ceramic capacitor close to the SUPPLY pin for C(SUPPLY) and a 10-nF ceramic capacitor close to the OUT pin for C(OUT). The larger capacitor for C(SUPPLY) or C(OUT) is helpful for EMI and ESD immunity; however, large C(OUT) takes a longer time to charge up the capacitor and may affect PWM dimming performance.