SLVSBA2E July   2012  – July 2025 DRV8844

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Switching Characteristics
    7. 5.7 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Output Stage
      2. 6.3.2 Logic Inputs
      3. 6.3.3 Bridge Control
      4. 6.3.4 Charge Pump
      5. 6.3.5 Protection Circuits
        1. 6.3.5.1 Overcurrent Protection (OCP)
        2. 6.3.5.2 Thermal Shutdown (TSD)
        3. 6.3.5.3 Undervoltage Lockout (UVLO)
    4. 6.4 Device Functional Modes
      1. 6.4.1 nRESET and nSLEEP Operation
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Motor Voltage
      3. 7.2.3 Application Curves
    3.     Power Supply Recommendations
      1. 7.3.1 Bulk Capacitance
    4. 7.3 Layout
      1. 7.3.1 Layout Guidelines
      2. 7.3.2 Layout Example
      3. 7.3.3 Thermal Considerations
        1. 7.3.3.1 Heatsinking
      4. 7.3.4 Power Dissipation
  9. 8 Device and Documentation Support
    1. 8.1 Documentation Support
      1. 8.1.1 Related Documentation
    2. 8.2 Community Resources
    3. 8.3 Trademarks
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

6.3.3 Bridge Control

The INx input pins directly control the state (high or low) of the OUTx outputs; the ENx input pins enable or disable the OUTx driver. Table 6-1 shows the logic.

Table 6-1 H-Bridge Logic
INxENxOUTx
X0Z
01L
11H

The inputs can also be used for PWM control of, for example, the speed of a DC motor. When controlling a winding with PWM, when the drive current is interrupted, the inductive nature of the motor requires that the current must continue to flow. This is called recirculation current. To handle this recirculation current, the H-bridge can operate in two different states, fast decay or slow decay. In fast decay mode, the H-bridge is disabled and recirculation current flows through the body diodes; in slow decay, the motor winding is shorted.

To PWM using fast decay, the PWM signal is applied to the ENx pin; to use slow decay, the PWM signal is applied to the INx pin. Table 6-2 is an example of driving a DC motor using OUT1 and OUT2 as an H-bridge:

Table 6-2 PWM Function
IN1EN1IN2EN2FUNCTION
PWM101Forward PWM, slow decay
01PWM1Reverse PWM, slow decay
1PWM0PWMForward PWM, fast decay
0PWM1PWMReverse PWM, fast decay

Figure 6-2 shows the current paths in different drive and decay modes:

DRV8844 Current PathsFigure 6-2 Current Paths