SLVSET1 August   2018 DRV8873

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Simplified Schematic
  4. 4 Revision History
  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 SPI 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 Bridge Control
        1. 7.3.1.1 Control Modes
        2. 7.3.1.2 Half-Bridge Operation
        3. 7.3.1.3 Internal Current Sense and Current Regulation
        4. 7.3.1.4 Slew-Rate Control
        5. 7.3.1.5 Dead Time
        6. 7.3.1.6 Propagation Delay
        7. 7.3.1.7 nFAULT Pin
        8. 7.3.1.8 nSLEEP as SDO Reference
      2. 7.3.2 Motor Driver Protection Circuits
        1. 7.3.2.1 VM Undervoltage Lockout (UVLO)
        2. 7.3.2.2 VCP Undervoltage Lockout (CPUV)
        3. 7.3.2.3 Overcurrent Protection (OCP)
          1. 7.3.2.3.1 Latched Shutdown (OCP_MODE = 00b)
          2. 7.3.2.3.2 Automatic Retry (OCP_MODE = 01b)
          3. 7.3.2.3.3 Report Only (OCP_MODE = 10b)
          4. 7.3.2.3.4 Disabled (OCP_MODE = 11b)
        4. 7.3.2.4 Open-Load Detection (OLD)
          1. 7.3.2.4.1 Open-Load Detection in Passive Mode (OLP)
          2. 7.3.2.4.2 Open-Load Detection in Active Mode (OLA)
        5. 7.3.2.5 Thermal Shutdown (TSD)
          1. 7.3.2.5.1 Latched Shutdown (TSD_MODE = 0b)
          2. 7.3.2.5.2 Automatic Recovery (TSD_MODE = 1b)
        6. 7.3.2.6 Thermal Warning (OTW)
      3. 7.3.3 Hardware Interface
        1. 7.3.3.1 MODE (Tri-Level Input)
        2. 7.3.3.2 Slew Rate
    4. 7.4 Device Functional Modes
      1. 7.4.1 Motor Driver Functional Modes
        1. 7.4.1.1 Sleep Mode (nSLEEP = 0)
        2. 7.4.1.2 Disable Mode (nSLEEP = 1, DISABLE = 1)
        3. 7.4.1.3 Operating Mode (nSLEEP = 1, DISABLE = 0)
        4. 7.4.1.4 nSLEEP Reset Pulse
    5. 7.5 Programming
      1. 7.5.1 Serial Peripheral Interface (SPI) Communication
        1. 7.5.1.1 SPI Format
        2. 7.5.1.2 SPI for a Single Slave Device
        3. 7.5.1.3 SPI for Multiple Slave Devices in Parallel Configuration
        4. 7.5.1.4 SPI for Multiple Slave Devices in Daisy Chain Configuration
    6. 7.6 Register Maps
      1. 7.6.1 Status Registers
        1. 7.6.1.1 FAULT Status Register Name (address = 0x00)
          1. Table 21. FAULT Status Register Field Descriptions
        2. 7.6.1.2 DIAG Status Register Name (address = 0x01)
          1. Table 22. DIAG Status Register Field Descriptions
      2. 7.6.2 Control Registers
        1. 7.6.2.1 IC1 Control Register (address = 0x02)
          1. Table 24. IC1 Control Register Field Descriptions
        2. 7.6.2.2 IC2 Control Register (address = 0x03)
          1. Table 25. IC2 Control Register Field Descriptions
        3. 7.6.2.3 IC3 Control Register (address = 0x04)
          1. Table 26. IC3 Control Register Field Descriptions
        4. 7.6.2.4 IC4 Control Register (address = 0x05)
          1. Table 27. IC4 Control Register Field Descriptions
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
        1. 8.2.1.1 Motor Voltage
        2. 8.2.1.2 Drive Current and Power Dissipation
        3. 8.2.1.3 Sense Resistor
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Thermal Considerations
        2. 8.2.2.2 Heatsinking
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
    1. 9.1 Bulk Capacitance Sizing
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 Package Option Addendum
      1. 12.1.1 Packaging Information
      2. 12.1.2 Tape and Reel Information

Package Options

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

7.5.1.4 SPI for Multiple Slave Devices in Daisy Chain Configuration

The device can be connected in a daisy chain configuration to keep GPIO ports available when multiple devices are communicating to the same MCU. Figure 24 shows the topology when three devices are connected in series.

DRV8873 drv8873-q1-daisy-chain-2a.gifFigure 24. Three DRV8873S Devices Connected in Daisy Chain

The first device in the chain receives data from the MCU in the following format for 3-device configuration: 2 bytes of header (HDRx) followed by 3 bytes of address (Ax) followed by 3 bytes of data (Dx).

DRV8873 drv8873-q1-daisy-chain-2b.gifFigure 25. SPI Frame With Three DRV8873S Devices

After the data has been transmitted through the chain, the MCU receives the data string in the following format for 3-device configuration: 3 bytes of status (Sx) followed by 2 bytes of header followed by 3 bytes of report (Rx).

DRV8873 drv8873-q1-daisy-chain-1a.gifFigure 26. SPI Data Sequence for Three DRV8873S Devices

The header bytes contain information of the number of devices connected in the chain, and a global clear fault command that will clear the fault registers of all the devices on the rising edge of the chip select (nSCS) signal. Header values N5 through N0 are 6 bits dedicated to show the number of devices in the chain. Up to 63 devices can be connected in series for each daisy chain connection.

The 5 LSBs of the HDR2 register are don’t care bits that can be used by the MCU to determine integrity of the daisy chain connection. Header bytes must start with 1 and 0 for the two MSBs.

DRV8873 drv8873-q1-daisy-chain-1b.gifFigure 27. Header Bytes

The status byte provides information about the fault status register for each device in the daisy chain so that the MCU does not have to initiate a read command to read the fault status from any particular device. This keeps additional read commands for the MCU and makes the system more efficient to determine fault conditions flagged in a device. Status bytes must start with 1 and 1 for the two MSBs.

DRV8873 drv8873-q1-daisy-chain-1d.gifFigure 28. Contents of Header, Status, Address, and Data Bytes

When data passes through a device, it determines the position of itself in the chain by counting the number of status bytes it receives followed by the first header byte. For example, in this 3-device configuration, device 2 in the chain receives two status bytes before receiving the HDR1 byte which is then followed by the HDR2 byte.

From the two status bytes, the data can determine that its position is second in the chain. From the HDR2 byte, the data can determine how many devices are connected in the chain. In this way, the data only loads the relevant address and data byte in its buffer and bypasses the other bits. This protocol allows for faster communication without adding latency to the system for up to 63 devices in the chain.

The address and data bytes remain the same with respect to a 1-device connection. The report bytes (R1 through R3), as shown in Figure 26, are the content of the register being accessed.

DRV8873 drv8873q1_spi_timing.gifFigure 29. SPI Transaction