TIDT280 May   2022

 

  1.   Description
  2.   Features
  3.   Applications
  4. 1Test Prerequisites
    1. 1.1 Voltage and Current Requirements
    2. 1.2 Considerations
    3. 1.3 Dimensions
  5. 2Testing and Results
    1. 2.1 Efficiency
    2. 2.2 Loss
    3. 2.3 Load Regulation
    4. 2.4 Line Regulation
    5. 2.5 Thermal Images
    6. 2.6 Bode Plots
      1. 2.6.1 9-V Input Voltage
      2. 2.6.2 24-V Input Voltage
      3. 2.6.3 48-V Input Voltage
      4. 2.6.4 56-V Input Voltage
  6. 3Waveforms
    1. 3.1 Switching
      1. 3.1.1 Transistor Q5 (Low-Side FET)
        1. 3.1.1.1 Drain - Source
          1. 3.1.1.1.1 9-V Input Voltage
          2. 3.1.1.1.2 56-V Input Voltage
        2. 3.1.1.2 Gate - Source
          1. 3.1.1.2.1 9-V Input Voltage
          2. 3.1.1.2.2 56-V Input Voltage
      2. 3.1.2 Transistor Q1 (High-Side FET)
        1. 3.1.2.1 Source - Drain (Referenced to VIN)
          1. 3.1.2.1.1 9-V Input Voltage
          2. 3.1.2.1.2 56-V Input Voltage
        2. 3.1.2.2 Gate - Source
          1. 3.1.2.2.1 9-V Input Voltage
          2. 3.1.2.2.2 56-V Input Voltage
    2. 3.2 Output Voltage Ripple
    3. 3.3 Input Voltage Ripple
    4. 3.4 Load Transients
      1. 3.4.1 9-V Input Voltage
      2. 3.4.2 56-V Input Voltage
    5. 3.5 Start-Up Sequence
      1. 3.5.1 9-V Input Voltage
      2. 3.5.2 56-V Input Voltage
    6. 3.6 Shutdown Sequence
      1. 3.6.1 9-V Input Voltage
      2. 3.6.2 56-V Input Voltage

Description

The LM5146-Q1 is used in this design as inverting buck-boost topology, generating –8 V out of the telecom input of +9 V to +56 V. By topology the controller is negative referenced, so a level shifter was added to provide an ENABLE function. The switching frequency of 400 kHz is a trade-off between switching losses and a reasonable board size.