SLVSAS7D February   2011  – March 2021 DRV8801-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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 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 Power Supervisor
      2. 7.3.2 Bridge Control
        1. 7.3.2.1 MODE 1
        2. 7.3.2.2 MODE 2
      3. 7.3.3 Fast Decay with Synchronous Rectification
      4. 7.3.4 Slow Decay with Synchronous Rectification (Brake Mode)
      5. 7.3.5 Charge Pump
      6. 7.3.6 SENSE
      7. 7.3.7 VPROPI
        1. 7.3.7.1 Connecting VPROPI Output to ADC
      8. 7.3.8 Protection Circuits
        1. 7.3.8.1 VBB Undervoltage Lockout (UVLO)
        2. 7.3.8.2 Overcurrent Protection (OCP)
        3. 7.3.8.3 Overtemperature Warning (OTW)
        4. 7.3.8.4 Overtemperature Shutdown (OTS)
      9. 7.3.9 Thermal Shutdown (TSD)
    4. 7.4 Device Functional Modes
  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 Motor Voltage
        2. 8.2.2.2 Power Dissipation
        3. 8.2.2.3 Thermal Considerations
          1. 8.2.2.3.1 Junction-to-Ambiant Thermal Impedance (ƟJA)
        4. 8.2.2.4 Motor Current Trip Point
        5. 8.2.2.5 Sense Resistor Selection
        6. 8.2.2.6 Drive Current
      3. 8.2.3 Pulse-Width Modulating
        1. 8.2.3.1 Pulse-Width Modulating ENABLE
        2. 8.2.3.2 Pulse-Width Modulating PHASE
      4. 8.2.4 Application Curves
    3. 8.3 Parallel Configuration
      1. 8.3.1 Parallel Connections
      2. 8.3.2 Non – Parallel Connections
      3. 8.3.3 Wiring nFAULT as Wired OR
      4. 8.3.4 Electrical Considerations
        1. 8.3.4.1 Device Spacing
        2. 8.3.4.2 Recirculation Current Handling
        3. 8.3.4.3 Sense Resistor Selection
        4. 8.3.4.4 Maximum System Current
  9. 9 Power Supply Recommendations
    1. 9.1 Bulk Capacitance
  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 Support 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

8.3.4.4 Maximum System Current

The idea behind placing multiple devices in parallel is to increase maximum drive current. At first glance, it may seem that the new increased ITRIP setting is given by Equation 8.

Equation 8. GUID-20201203-CA0I-WZ45-8RHT-FWZD9CFWRKWJ-low.gif

Where:

N is the number of devices connected in parallel.

ITRIP is the individual ITRIP value per device.

However, although in theory accurate, due to tolerances in internal SENSE amplifier/comparator circuitry, the system ITRIP should be expected to be less than the addition of all the individual ITRIP. The reason for this is that as soon as one of the devices senses a current for which the H Bridge should be disabled, the remaining devices will end up having to conduct the same current but with less capacity. Therefore, remaining devices are expected to get disabled shortly after.

A good rule of thumb is to expect 90% of the theoretical maximum.

By way of example, if the system level requirements indicate that 6 A of current are required to meet the motion control requirements, then:

6 A = (2.8 A x 0.9)N

N = (6 A) / (2.8 A x 0.9)

N = 2.38

In this example, three devices would be required to safely meet the needs of the system.