JAJSNQ5 may   2023 TPS92629-Q1

PRODUCTION DATA  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 説明
  5. 4 Revision History
  6. 5 Pin Configuration and Functions
  7. 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
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Power Supply (SUPPLY)
        1. 7.3.1.1 Power-On Reset (POR)
        2. 7.3.1.2 Supply Current in Fault Mode
      2. 7.3.2  Enable and Shutdown
      3. 7.3.3  Constant-Current Output and Setting (IN)
      4. 7.3.4  Thermal Sharing Resistor (OUT and RES)
      5. 7.3.5  Brightness Control (EN/PWM and ADIM)
      6. 7.3.6  Diagnostics
        1. 7.3.6.1 LED Short-to-GND Detection
        2. 7.3.6.2 LED Open-Circuit and Short-to-Battery Detection
        3. 7.3.6.3 LED Open-Circuit and Short-to-Battery Detection Enable (DIAGEN)
        4. 7.3.6.4 Overtemperature Protection
        5. 7.3.6.5 Low Dropout Operation
      7. 7.3.7  Multi Fault Report
      8. 7.3.8  FAULT Table
      9. 7.3.9  LED Fault Summary
      10. 7.3.10 IO Pins Inner Connection
    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
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Using Analog Dimming Controlled By MCU for Blind Spot Detection
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 ドキュメントの更新通知を受け取る方法
    2. 9.2 サポート・リソース
    3. 9.3 Trademarks
    4. 9.4 静電気放電に関する注意事項
    5. 9.5 用語集
  11. 10Mechanical, Packaging, and Orderable Information

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 sensing resistor, R(SNSx) by using Equation 3.

Equation 3. GUID-5D9E78CB-03A7-4069-88E6-E695360537F5-low.gif

where

  • V(CS_REG) = 463.5 mV (typical)
  • I(OUTx_Tot) = 100 mA

According to design requirements, output current for the LED channel is 100 mA so that the calculated R(SNS) = 4.63 Ω and a 4.64 Ω resistor is selected.

Step 2: Design the current distribution between I(OUTx) and I(RESx), and calculate the current sharing resistor, R(RESx), by using Equation 4. The R(RESx) value actually decides the current distribution for I(OUTx) path and I(RESx) path, basic principle is to design the R(RESx) to consume appropriate 50% total power dissipation at typical supply operating voltage.

Equation 4. GUID-9A6B99C2-B83B-4E45-AB0E-5D587C5AB79D-low.gif

where

  • V(SUPPLY) = 12 V (typical)
  • I(OUTx_Tot) = 100 mA (maximum)

The calculated result for R(RES) resistor value is 108 Ω when V(OUTx) is typical 3 × 2.2 V = 6.6 V. A 107 Ω resistor is selected

Step 3: Design the threshold voltage of SUPPLY to enable the LED open-circuit, and calculate voltage divider resistor value for R1 and R2 on DIAGEN pin.

The maximum forward voltage of LED-string is 3 × 2.5 V = 7.5 V. To avoid the open-circuit fault or short-to-battery fault reported in low-dropout operation conditions, additional headroom between SUPPLY and OUTx must be considered. TheTPS92629-Q1 device must disable open-circuit and short-to-battery detection when the supply voltage is below LED-string maximum forward voltage plus V(OPEN_th_rising) and V(CS_REG). The voltage divider resistor, R1 and R2 value can be calculated by Equation 5.

Equation 5. GUID-AE489D99-71DA-4A4F-B967-047FFA09F929-low.gif

where

  • V(OPEN_th_rising) = 420 mV (maximum)
  • V(CS_REG) = 489 mV (maximum)
  • VIL(DIAGEN) = 1.045 V (minimum)
  • R2 = 10 kΩ (recommended)

The calculated result for R1 is 70.5 kΩ when V(OUTx) maximum voltage is 7.5 V and V(CS_REG) is 420 mV. A 70.6 kΩ resistor is selected