SLVSFZ6 December   2021 DRV8251

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
    7. 7.7 Timing Diagrams
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 External Components
    4. 8.4 Feature Description
      1. 8.4.1 Bridge Control
      2. 8.4.2 Current Regulation
      3. 8.4.3 Protection Circuits
        1. 8.4.3.1 Overcurrent Protection (OCP)
        2. 8.4.3.2 Thermal Shutdown (TSD)
        3. 8.4.3.3 VM Undervoltage Lockout (UVLO)
    5. 8.5 Device Functional Modes
      1. 8.5.1 Active Mode
      2. 8.5.2 Low-Power Sleep Mode
      3. 8.5.3 Fault Mode
    6. 8.6 Pin Diagrams
      1. 8.6.1 Logic-Level Inputs
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Brush DC Motor
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Motor Voltage
          2. 9.2.1.2.2 Motor Current
          3. 9.2.1.2.3 Sense Resistor
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Stall Detection
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
          1. 9.2.2.2.1 Stall Detection Timing
          2. 9.2.2.2.2 Stall Threshold Selection
        3. 9.2.2.3 Application Curves
      3. 9.2.3 Relay Driving
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
          1. 9.2.3.2.1 Control Interface for Single-Coil Relays
          2. 9.2.3.2.2 Control Interface for Dual-Coil Relays
        3. 9.2.3.3 Application Curves
      4. 9.2.4 Multi-Sourcing with Standard Motor Driver Pinout
    3. 9.3 Current Capability and Thermal Performance
      1. 9.3.1 Power Dissipation and Output Current Capability
      2. 9.3.2 Thermal Performance
        1. 9.3.2.1 Steady-State Thermal Performance
        2. 9.3.2.2 Transient Thermal Performance
  10. 10Power Supply Recommendations
    1. 10.1 Bulk Capacitance
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information
9.2.3.2.2 Control Interface for Dual-Coil Relays

A dual coil relay only require two low-side drivers if the center tap is connected to VM. The body diodes of the unused FETs act as freewheeling diodes, so additional freewheeling diodes are not needed when driving a dual-coil relay with the DRV8251. The PWM interface can be used to control the dual-coil relay. The following figures show the schematic and timing diagram for driving dual-coil relays.

Figure 9-11 Schematic of dual-coil relay driven by the OUTx H-bridge
Figure 9-12 Timing diagram for driving a dual-coil relay with PWM interface

Table 9-4 shows the logic table for the PWM interface. The descriptions in this table reflect how the input and output states drive the dual coil relay. When Coil1 is driven (OUT1 voltage is at GND), The voltage at OUT2 will go to VM. Because the center tap of the relay is also at VM, no current flows through Coil2. The same is true when Coil2 is driven; Coil1 shorts to VM. The body diodes of the high-side FETs act as freewheeling diodes, so extra external diodes are not needed. Figure 9-15 shows oscilloscope traces for this application.

Table 9-4 PWM control table for dual-coil relay driving
IN1 IN2 OUT1 OUT2 DESCRIPTION
0 0 Hi-Z Hi-Z Outputs disabled (H-Bridge Hi-Z)
0 1 L H Drive Coil1
1 0 H L Drive Coil2
1 1 L L Drive Coil1 and Coil2 (invalid state for a dual-coil latching relay)