SLVSF66A August   2019  – December  2019 DRV8874

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      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 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 Control Modes
        1. 7.3.2.1 PH/EN Control Mode (PMODE = Logic Low)
        2. 7.3.2.2 PWM Control Mode (PMODE = Logic High)
        3. 7.3.2.3 Independent Half-Bridge Control Mode (PMODE = Hi-Z)
      3. 7.3.3 Current Sense and Regulation
        1. 7.3.3.1 Current Sensing
        2. 7.3.3.2 Current Regulation
          1. 7.3.3.2.1 Fixed Off-Time Current Chopping
          2. 7.3.3.2.2 Cycle-By-Cycle Current Chopping
      4. 7.3.4 Protection Circuits
        1. 7.3.4.1 VM Supply Undervoltage Lockout (UVLO)
        2. 7.3.4.2 VCP Charge Pump Undervoltage Lockout (CPUV)
        3. 7.3.4.3 OUTx Overcurrent Protection (OCP)
        4. 7.3.4.4 Thermal Shutdown (TSD)
        5. 7.3.4.5 Fault Condition Summary
      5. 7.3.5 Pin Diagrams
        1. 7.3.5.1 Logic-Level Inputs
        2. 7.3.5.2 Tri-Level Inputs
        3. 7.3.5.3 Quad-Level Inputs
    4. 7.4 Device Functional Modes
      1. 7.4.1 Active Mode
      2. 7.4.2 Low-Power Sleep Mode
      3. 7.4.3 Fault Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Primary Application
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Current Sense and Regulation
          2. 8.2.1.2.2 Power Dissipation and Output Current Capability
          3. 8.2.1.2.3 Thermal Performance
            1. 8.2.1.2.3.1 Steady-State Thermal Performance
            2. 8.2.1.2.3.2 Transient Thermal Performance
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Alternative Application
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1 Current Sense and Regulation
        3. 8.2.2.3 Application Curves
  9. 9 Power Supply Recommendations
    1. 9.1 Bulk Capacitance
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
      1. 10.2.1 HTSSOP 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

Package Options

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

7.3.3.2 Current Regulation

The DRV887x family of devices integrate current regulation using either a fixed off-time or cycle-by-cycle PWM current chopping scheme. The current chopping scheme is selectable through the IMODE quad-level input. This allows the devices to limit the output current in case of motor stall, high torque, or other high current load events.

The IMODE level can be set by leaving the pin floating (Hi-Z), connecting the pin to GND, or connecting a resistor between IMODE and GND. The IMODE pin state is latched when the device is enabled through the nSLEEP pin. The IMODE state can be changed by taking the nSLEEP pin logic low, waiting the tSLEEP time, changing the IMODE pin input, and then enabling the device by taking the nSLEEP pin back logic high. The IMODE input is also used to select the device response to an overcurrent event. See more details in the Protection Circuits section.

The internal current regulation can be disabled by tying IPROPI to GND and setting the VREF pin voltage greater than GND (if current feedback is not required) or if current feedback is required, setting VVREF and RIPROPI such that VIPROPI never reaches the VVREF threshold. In independent half-bridge control mode (PMODE = Hi-Z), the internal current regulation is automatically disabled since the outputs are operating independently and the current sense and regulation is shared between half-bridges.

Table 6. IMODE Functions

IMODE STATE IMODE FUNCTION nFAULT
Response
Current Chopping Mode Overcurrent
Response
Quad-Level 1 RIMODE = GND Fixed Off-Time Automatic Retry Overcurrent Only
Quad-Level 2 RIMODE = 20 kΩ to GND Cycle-By-Cycle Automatic Retry Current Chopping and Overcurrent
Quad-Level 3 RIMODE = 62 kΩ to GND Cycle-By-Cycle Outputs Latched Off Current Chopping and Overcurrent
Quad-Level 4 RIMODE = Hi-Z Fixed Off-Time Outputs Latched Off Overcurrent Only

The current chopping threshold (ITRIP) is set through a combination of the VREF voltage (VVREF) and IPROPI output resistor (RIPROPI). This is done by comparing the voltage drop across the external RIPROPI resistor to VVREF with an internal comparator.

Equation 3. ITRIP (A) x AIPROPI (μA/A) = VVREF (V) / RIPROPI (Ω)

For example, if VVREF = 2.5 V, RIPROPI = 1500 Ω, and AIPROPI = 455 μA/A, then ITRIP will be approximately 3.66 A.

When the ITRIP threshold is exceeded, the outputs will enter a current chopping mode according to the IMODE setting. The ITRIP comparator has both a blanking time (tBLK) and a deglitch time (tDEG). The internal blanking time helps to prevent voltage and current transients during output switching from effecting the current regulation. These transients may be caused by a capacitor inside the motor or on the connections to the motor terminals. The internal deglitch time ensures that transient conditions do not prematurely trigger the current regulation. In certain cases where the transient conditions are longer than the deglitch time, placing a 10-nF capacitor on the IPROPI pin, close to the DRV887x, will help filter the transients on IPROPI output so current regulation does not prematurely trigger. The capacitor value can be adjusted as needed, however large capacitor values may slow down the response time of the current regulation circuitry.

The AERR parameter in the Electrical Characteristics table is the error associated with the AIPROPI gain. It indicates the combined effect of offset error added to the IOUT current and gain error.