JAJSOU2 December   2024 TPS4813-Q1

PRODUCTION DATA  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 概要
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Switching Characteristics
    7. 5.7 Typical Characteristics
  7. 6 Parameter Measurement Information
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Charge Pump and Gate Driver Output (VS, G1PU, G1PD, BST, SRC)
      2. 7.3.2 Capacitive Load Driving
        1. 7.3.2.1 Using Low-Power Bypass FET (G2 Drive) for Load Capacitor Charging
        2. 7.3.2.2 Using Main FET's (G1 Drive) Gate Slew Rate Control
      3. 7.3.3 Short-Circuit Protection
        1. 7.3.3.1 Short-Circuit Protection With Auto-Retry
        2. 7.3.3.2 Short-Circuit Protection With Latch-Off
      4. 7.3.4 Undervoltage Protection (UVLO)
      5. 7.3.5 Reverse Polarity Protection
      6. 7.3.6 Short-Circuit Protection Diagnosis (SCP_TEST)
    4. 7.4 Device Functional Modes
      1. 7.4.1 State Diagram
      2. 7.4.2 State Transition Timing Diagram
      3. 7.4.3 Power Down
      4. 7.4.4 Shutdown Mode
      5. 7.4.5 Low Power Mode
      6. 7.4.6 Active Mode
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application 1: Driving Power At All Times (PAAT) Loads With Automatic Load Wakeup
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
    3. 8.3 Typical Application 2: Driving Power At All Times (PAAT) Loads With Automatic Load Wakeup and Output Bulk Capacitor Charging
      1. 8.3.1 Design Requirements
      2. 8.3.2 External Component Selection
      3. 8.3.3 Application Curves
    4. 8.4 TIDA-020065: Automotive Smart Fuse Reference Design Driving Power At All Times (PAAT) Loads With Automatic Load Wakeup, Output Bulk Capacitor Charging, Bi-directional Current Sensing and Software I2t
    5. 8.5 Power Supply Recommendations
    6. 8.6 Layout
      1. 8.6.1 Layout Guidelines
      2. 8.6.2 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. 10Revision History
  12. 11Mechanical, 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

8.3.2 External Component Selection

By following similar design procedure as outlined in Section 8.2.2, the external component values are calculated as below:

  • CBST = 220nF
  • RISCP = 48.1kΩ to set 100A as short-circuit protection threshold
  • CTMR = 1.5nF to set 20μs short-circuit protection delay
  • R4 and R5 are selected as 470kΩ and 24.9kΩ respectively to set VIN undervoltage lockout threshold at 24V

Programming the Inrush Current – R3 and CDVDT Selection

Use following equation to calculate the IINRUSH:

Equation 22. IINRUSH= COUT× VBATT_MAXTcharge

Use following equation to calculate the required Cg based on IINRUSH calculated in Equation 23.

Equation 23. Cg = CLOAD × I(G)IINRUSH

Where,

I(G) is 165µA (typical),

To set IINRUSH at 1.65A, Cg value is calculated to be ~22nF.

A series resistor Rg must be used in conjunction with Cg to limit the discharge current from Cg during turn-off . The chosen value of R3 is 100Ω and Cg is 22nF.

Programming the Load Wakeup Threshold – RBYPASS and Q3 Selection

During normal operation, the resistor RBYPASS along with bypass FET RDSON is used to set load wakeup current threshold.

For selecting the MOSFET Q3, important electrical parameters are the maximum continuous drain current ID, the maximum drain-to-source voltage VDS(MAX), the maximum drain-to-source voltage VGS(MAX), and the drain-to-source ON resistance RDSON.

Based on the design requirements, IAUS200N08S5N023 is selected and its ratings are:

  • 80V VDS(MAX) and ±20V VGS(MAX)
  • RDS(ON) is 2.7mΩ typical at 10V VGS
  • MOSFET Qg(total) is 85nC typical
  • MOSET VGS(th) is 2.2V min
  • MOSFET CISS is 5900pF typical

The recommended range of the short-circuit threshold voltage which is same as load wakeup threshold, V(SCP/LWU), extends from 20mV to 500mV. Values near the low threshold of 20mV can be affected by the system noise. Values near the upper threshold of 500mV would result in high short-circuit current threshold. To minimize both the concerns, 50mV is selected as the short-circuit or load wakeup threshold voltage.

The V(SCP/LWU) value can also be calculated based on selected RISCP resistor by following equation:

Equation 24. V(SCP/LWU) (mV)= 2 μA × RISCP +19 mV

RBYPASS resistor value can be selected using below equation:

Equation 25. RBYPASS = V(SCP/LWU)ILWU -RDSON_BYPASS

To set 50 mA as load wakeup threshold, RBYPASS value is calculated to be ~ 2.3Ω.

The average power rating of the bypass resistor can be calculated by following equation:

Equation 26. PAVG= ILWU2× RBYPASS

The average power dissipation of RBYPASS is calculated to be ~5.75 mW.

The peak power dissipation in the bypass resistor is given by following equation:

Equation 27. PPEAK= VBATT_MAX2RBYPASS

The peak power dissipation of RBYPASS is calculated to be ~1565 W.

The peak power dissipation time for power-up with short into LPM can be calculated based on following equation:

Equation 28. TPULSE= CISS× V(G2_GOOD) - VGS(th)I(G2) + 10 µs

where,

V(G2_GOOD) is internal threshold with 7V (typical) value,

I(G2) is 165μA (typical),

VGS(th) is gate to source voltage and CISS is effective input capacitance of selected bypass FET.

Based on Equation 28, TPULSE is calculated to be ~182μs.

Two 4.7Ω, 1.5W, 1% CRCW25124R70FKEGHP resistor are used in parallel to support both average and peak power dissipation for >TPULSE time calculated in Equation 28.

TI suggests the designer to share the entire power dissipation profile of bypass resistor with the resistor manufacturer and get their recommendation.

The peak short-circuit current in bypass path can be calculated based on following equation:

Equation 29. IPEAK_BYPASS=VIN_MAXRBYPASS

IPEAK_BYPASS is calculated to be 26A based on RBYPASS selected in Equation 25.

TI suggest the designer to ensure that operating point (VBATT_MAX, IPEAK_BYPASS) for bypass path (Q3) is within the SOA curve for >TPULSE time calculated in Equation 28.