SLVSI75 May   2026 DRV8218

ADVANCE INFORMATION  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  6. 5 Pin Configuration and Functions
  7. 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 Transient Current Capability
    7. 6.7 Timing Diagrams
    8. 6.8 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 External Components
    4. 7.4 Feature Description
      1. 7.4.1 Control Modes
        1. 7.4.1.1 PWM Control Mode (MODE = 0)
        2. 7.4.1.2 PH/EN Control Mode (MODE = 1)
        3. 7.4.1.3 Independent Half-Bridge Control Mode (MODE = Hi-Z)
      2. 7.4.2 Pin Diagrams
        1. 7.4.2.1 Logic-Level Inputs
        2. 7.4.2.2 Tri-Level Input
      3. 7.4.3 Protection Circuits
        1. 7.4.3.1 Supply Undervoltage Lockout (UVLO)
        2. 7.4.3.2 OUTx Overcurrent Protection (OCP)
        3. 7.4.3.3 Thermal Shutdown (TSD)
    5. 7.5 Device Functional Modes
      1. 7.5.1 Active Mode
      2. 7.5.2 Low-Power Sleep Mode
      3. 7.5.3 Fault Mode
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Full-Bridge Driving
        1. 8.2.1.1 Supply Voltage
        2. 8.2.1.2 Control Interface - Full Bridge
        3. 8.2.1.3 Low-Power Operation
        4. 8.2.1.4 Application Curves
      2. 8.2.2 Half-Bridge Driving
        1. 8.2.2.1 Control Interface
        2. 8.2.2.2 Low-Power Operation
        3. 8.2.2.3 Application Curves
      3. 8.2.3 Parallel Multiple Drivers
      4. 8.2.4 Dual-Coil Relay Driving
        1. 8.2.4.1 Control Interface
        2. 8.2.4.2 Low-Power Operation
        3. 8.2.4.3 Application Curves
      5. 8.2.5 Current Sense
        1. 8.2.5.1 Design Requirements
        2. 8.2.5.2 Detailed Design Procedure
          1. 8.2.5.2.1 Shunt Resistor Sizing
          2. 8.2.5.2.2 RC Filter
    3. 8.3 Current Capability and Thermal Performance
      1. 8.3.1 Power Dissipation and Output Current Capability
    4. 8.4 Power Supply Recommendations
      1. 8.4.1 Bulk Capacitance
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
      2. 8.5.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Mechanical, Packaging, and Orderable Information

8.3.1 Power Dissipation and Output Current Capability

Total power dissipation for the device consists of three main components: quiescent supply current dissipation (PVM and PVCC), the power MOSFET switching losses (PSW), and the power MOSFET RDS(on) (conduction) losses (PRDS). While other factors can contribute additional power losses, these other losses are typically insignificant compared to the three main items.

Equation 2. PTOT = PVM + PVCC + PSW + PRDS

PVM can be calculated from the nominal motor supply voltage (VVM) and the IVM active mode current specification. PVCC can be calculated from the nominal logic supply voltage (VVCC) and the IVCC active mode current specification. When VVCC < VVM, the DRV8218 draws active current from the VM pin rather than the VCC pin. During this operating condition, IVCC is typically less than 500nA.

Equation 3. PVM = VVM x IVM
Equation 4. PVM = 7.5mW = 5V x 1.5mA
Equation 5. PVCC = VVCC x IVCC
Equation 6. PVCC = 1.0mW = 3.3V x 0.3mA

PSW can be calculated from the nominal motor supply voltage (VVM), average output current (IRMS), switching frequency (fPWM) and the device output rise (tRISE) and fall (tFALL) time specifications.

Equation 7. PSW = PSW_RISE + PSW_FALL
Equation 8. PSW_RISE = 0.5 x VM x IRMS x tRISE x fPWM
Equation 9. PSW_FALL = 0.5 x VM x IRMS x tFALL x fPWM
Equation 10. PSW_RISE = 15mW = 0.5 x 5V x 2.0A x 150ns x 20kHz
Equation 11. PSW_FALL = 15mW = 0.5 x 5V x 2.0A x 150ns x 20kHz
Equation 12. PSW = 30mW = 15mW + 15mW

PRDS can be calculated from the device RDS(on) and average output current (IRMS).

Equation 13. PRDS = IRMS2 x (RDS(ON)_HS + RDS(ON)_LS)

RDS(ON) has a strong correlation with the device temperature. Assuming a device junction temperature of 85°C, RDS(on) can increase approximately 1.5x based on the normalized temperature data. The calculation below shows this derating factor. Alternatively, the Section 6.8 section shows curves that plot how RDS(on) changes with temperature.

Equation 14. PRDS = 480mW = (2.0A)2 x (40mΩ x 1.5 + 40mΩ x 1.5)

Based on the example calculations above, the expressions below calculate the total expected power dissipation for the device.

Equation 15. PTOT = PVM + PVCC + PSW + PRDS
Equation 16. PTOT = 518mW = 7.5mW + 1.0mW + 30mW + 480mW

The driver junction temperature can be estimated using PTOT, device ambient temperature (TA), and package thermal resistance (RθJA). The value for RθJA depends heavily on the PCB design and copper heat sinking around the device.

Equation 17. TJ = (PTOT x RθJA) + TA
Equation 18. TJ = 117°C = (0.518W × 60.9°C/W) + 85°C

The device junction temperature must remain below the absolute maximum rating for all system operating conditions. The calculations in this section provide reasonable estimates for junction temperature. However, other methods based on temperature measurements taken during system operation are more realistic and reliable. Additional information on motor driver current ratings and power dissipation can be found in Section 9.1.1.

The motor driver can experience different transient driving conditions that cause large currents to flow for a short duration of time. These can include

  • Motor start-up when the rotor is initially stationary.
  • Fault conditions when there is a supply or ground short to one of the motor outputs, and the overcurrent protection triggers.
  • Briefly energizing a motor or solenoid for a limited time, then de-energizing.

See Understanding Motor Driver Current Ratings Application Report for a deeper explanation of the meaning of different current ratings on TI motor drivers and PCB layout techniques.