SLLSFA7A July   2020  – April 2021 DRV8706-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Descriptions
  4. 4 Revision History
  5. 5 Pin Configuration
    1.     DRV8706-Q1_RHB Package (VQFN) 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 Timing Diagrams
    8. 6.8 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 External Components
      2. 7.3.2 Device Interface Variants
        1. 7.3.2.1 Serial Peripheral Interface (SPI)
        2. 7.3.2.2 Hardware (H/W)
      3. 7.3.3 Input PWM Modes
        1. 7.3.3.1 Half-Bridge Control
        2. 7.3.3.2 H-Bridge Control
        3. 7.3.3.3 Split HS and LS Solenoid Control
      4. 7.3.4 Smart Gate Driver
        1. 7.3.4.1 Functional Block Diagram
        2. 7.3.4.2 Slew Rate Control (IDRIVE)
        3. 7.3.4.3 Gate Drive State Machine (TDRIVE)
      5. 7.3.5 Doubler (Single-Stage) Charge Pump
      6. 7.3.6 Wide Common Mode Differential Current Shunt Amplifier
      7. 7.3.7 Pin Diagrams
        1. 7.3.7.1 Logic Level Input Pin (DRVOFF, IN1/EN, IN2/PH, nHIZx, nSLEEP, nSCS, SCLK, SDI)
        2. 7.3.7.2 Logic Level Push Pull Output (SDO)
        3. 7.3.7.3 Logic Level Open Drain Output (nFAULT)
        4. 7.3.7.4 Quad-Level Input (GAIN)
        5. 7.3.7.5 Six-Level Input (IDRIVE, VDS)
      8. 7.3.8 Protection and Diagnostics
        1. 7.3.8.1  Gate Driver Disable and Enable (DRVOFF and EN_DRV)
        2. 7.3.8.2  Fault Reset (CLR_FLT)
        3. 7.3.8.3  DVDD Logic Supply Power on Reset (DVDD_POR)
        4. 7.3.8.4  PVDD Supply Undervoltage Monitor (PVDD_UV)
        5. 7.3.8.5  PVDD Supply Overvoltage Monitor (PVDD_OV)
        6. 7.3.8.6  VCP Charge Pump Undervoltage Lockout (VCP_UV)
        7. 7.3.8.7  MOSFET VDS Overcurrent Protection (VDS_OCP)
        8. 7.3.8.8  Gate Driver Fault (VGS_GDF)
        9. 7.3.8.9  Thermal Warning (OTW)
        10. 7.3.8.10 Thermal Shutdown (OTSD)
        11. 7.3.8.11 Offline Short Circuit and Open Load Detection (OOL and OSC)
        12. 7.3.8.12 Fault Detection and Response Summary Table
    4. 7.4 Device Function Modes
      1. 7.4.1 Inactive or Sleep State
      2. 7.4.2 Standby State
      3. 7.4.3 Operating State
    5. 7.5 Programming
      1. 7.5.1 SPI Interface
      2. 7.5.2 SPI Format
      3. 7.5.3 SPI Interface for Multiple Slaves
        1. 7.5.3.1 SPI Interface for Multiple Slaves in Daisy Chain
    6. 7.6 Register Maps
      1. 7.6.1 STATUS Registers
      2. 7.6.2 CONTROL Registers
  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 Gate Driver Configuration
          1. 8.2.2.1.1 VCP Load Calculation Example
          2. 8.2.2.1.2 IDRIVE Calculation Example
        2. 8.2.2.2 Current Shunt Amplifier Configuration
        3. 8.2.2.3 Power Dissipation
      3. 8.2.3 Application Curves
  9. 9 Layout
    1. 9.1 Layout Guidelines
    2. 9.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Documentation Support
      1. 10.1.1 Related Documentation
      2. 10.1.2 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • RHB|32
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.2.2.2 Current Shunt Amplifier Configuration

The DRV8706-Q1 differential shunt amplifier gain and shunt resistor value are selected based on the dynamic current range, reference voltage supply, shunt resistor power rating, and operating temperature range. In bidirectional operation of the shunt amplifier, the dynamic range at the output is approximately calculated as shown in Equation 9. The output of the amplifier can swing from the midpoint reference (VAREF / 2) to either 0.25 V or VAREF - 0.25V depending on the polarity of the input voltage to the amplifer.

Equation 9. VSO_BI = (VAREF - 0.25 V) - (VAREF / 2)

If only unidirectional current sensing is required, the amplifier reference can be modified to expand the dynamic range at the output. The is modified through the CSA_DIV SPI register setting. In this mode, the dynamic range at the output is approximately calculated as shown in Equation 10.

Equation 10. VSO_UNI = (VAREF - 0.25 V) - (VAREF / 8)

Based on VAREF = 3.3 V, the dynamic out range in both bidirectional or unidirectional sensing can be calculated as shown below.

Equation 11. VSO_BI = (3.3 V - 0.25 V) - (3.3 V / 2) = 1.4 V
Equation 12. VSO_UNI = (3.3 V - 0.25 V) - (3.3 V / 8) = 2.6375 V

The external shunt resistor value andDRV8706-Q1 shunt amplifier gain setting are selected based on the available dynamic output range, the shunt resistor power rating, and maximum motor current that needs to be measured. This exact values for the shunt resistance and amplifier gain are determine by both Equation 13 and Equation 14.

Equation 13. RSHUNT < PSHUNT / IMAX2
Equation 14. AV < VSO / (IMAX x RSHUNT)

Based on VSO = 1.4 V, IMAX = 25 A and PSHUNT = 3 W, the values for shunt resistance and amplifier gain can be calculated as shown below.

Equation 15. RSHUNT < 3 W / 252 A = 4.8 mΩ
Equation 16. AV < 1.4 V / (25 A x 4.8 mΩ) = 11.67 V/V

Based on the results, a shunt resistance of 4 mΩ and an amplifier gain of 10 V/V can be selected.