SNOSB30Q October   2008  – March 2026 LMH6554

PRODUCTION DATA  

  1.   1
  2. 1Features
  3. 2Applications
  4. 3Description
  5. 4Pin Configuration and Functions
    1.     Pin Functions
  6. 5Specifications
    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: +5 V
    6. 5.6 Typical Performance Characteristics VS = ±2.5 V
  7. 6Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
    4. 6.4 Device Functional Modes
  8. 7Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Single-Ended Input to Differential Output Operation
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
          1. 7.2.1.2.1 Enable / Disable Operation
          2. 7.2.1.2.2 Single-Ended Input to Differential Output Operation
          3. 7.2.1.2.3 Driving Capacitive Loads
        3. 7.2.1.3 Application Curves
      2. 7.2.2 Fully Differential Operation
      3. 7.2.3 Single Supply Operation
      4. 7.2.4 Driving Analog-to-Digital Converters
      5. 7.2.5 Output Noise Performance and Measurement
      6. 7.2.6 Balanced Cable Driver
    3. 7.3 Power Supply Recommendations
      1. 7.3.1 Power Supply Bypassing
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
      3. 7.4.3 Power Dissipation
      4. 7.4.4 ESD Protection
  9. 8Device and Documentation Support
    1. 8.1 Device Support
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Trademarks
  10. 9Revision History
  11.   Mechanical, Packaging, and Orderable Information

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7.4.3 Power Dissipation

The LMH6554 is optimized for maximum speed and performance in a small form factor 14 lead UQFN package. To ensure maximum output drive and highest performance, thermal shutdown is not provided. Therefore, it is of utmost importance to make sure that the TJMAX is never exceeded due to the overall power dissipation.

Follow these steps to determine the maximum power dissipation for the LMH6554:

  1. Calculate the quiescent (no-load) power:
    Equation 1. PAMP = ICC * (VS)

    where

    • VS = V+ − V-. (Be sure to include any current through the feedback network if VCM is not mid-rail)
  2. Calculate the RMS power dissipated in each of the output stages:
    Equation 2. PD (rms) = rms ((VS − V+OUT) * I+OUT) + rms ((VS − V-OUT) * I-OUT)

    where

    • VOUT and IOUT are the voltage
    • the current measured at the output pins of the differential amplifier as if they were single ended amplifiers
    • VS is the total supply voltage
  3. Calculate the total RMS power:
    Equation 3. PT = PAMP + PD

The maximum power that the LMH6554 package can dissipate at a given temperature can be derived with the following equation:

Equation 4. PMAX = (150° − TAMB)/ θJA

where

  • TAMB = Ambient temperature (°C)
  • θJA = Thermal resistance, from junction to ambient, for a given package (°C/W)
  • For the 14 lead UQFN package, θJA is 60°C/W
Note:

If VCM is not 0V then there will be quiescent current flowing in the feedback network. This current should be included in the thermal calculations and added into the quiescent power dissipation of the amplifier.