TIDT330 june   2023

 

  1.   1
  2.   Description
  3.   Features
  4.   Applications
  5. 1Test Prerequisites
    1. 1.1 Voltage and Current Requirements
    2. 1.2 Considerations
    3. 1.3 Dimensions
  6. 2Testing and Results
    1. 2.1 Efficiency Graphs
      1. 2.1.1 One Low-Side FET , 680-nH Coil , 1.0 VIN – 1.5 VIN
      2. 2.1.2 One Low-Side FET , 680-nH Coil , 2.0 VIN – 3.0 VIN
    2. 2.2 Load Regulation
      1. 2.2.1 One Low-Side FET, 680-nH Coil, 1.0 VIN – 1.5 VIN
      2. 2.2.2 One Low-Side FET, 680-nH Coil, 2.0 VIN – 3.0 VIN
    3. 2.3 Thermal Images
      1. 2.3.1 1.0-V Input Voltage – Full Load 3.0 A
        1. 2.3.1.1 Two Low-Side FETs, 330-nH Coil
        2. 2.3.1.2 One Low-Side FET, 680-nH Coil
      2. 2.3.2 2.0-V Input Voltage, Full Load 3.0 A
        1. 2.3.2.1 Two Low-Side FETs, 330-nH Coil
      3. 2.3.3 3.0-V Input Voltage, Full Load 3.0 A
        1. 2.3.3.1 Two Low-Side FETs, 330-nH Coil
    4. 2.4 Bode Plots
      1. 2.4.1 1.0-V Input Voltage
      2. 2.4.2 2.0-V Input Voltage
      3. 2.4.3 3.0-V Input Voltage
  7. 3Waveforms
    1. 3.1 Switching Q2 FET (Drain to Source)
      1. 3.1.1 1.0-V Input Voltage
      2. 3.1.2 3.0-V Input Voltage
    2. 3.2 Output Voltage Ripple
      1. 3.2.1 1.0-V Input Voltage
      2. 3.2.2 3.0-V Input Voltage
    3. 3.3 Input Voltage Ripple
      1. 3.3.1 1.0-V Input Voltage
      2. 3.3.2 3.0-V Input Voltage
    4. 3.4 Load Transients
      1. 3.4.1 Load Steps of 1.5 A to 3 A
        1. 3.4.1.1 1.0-V Input Voltage
        2. 3.4.1.2 3.0-V Input Voltage
      2. 3.4.2 Load Steps of 0.2 A to 3 A
        1. 3.4.2.1 1.0-V Input Voltage
        2. 3.4.2.2 3.0-V Input Voltage
    5. 3.5 Start-Up Sequence
      1. 3.5.1 1.0-V Input Voltage
      2. 3.5.2 3.0-V Input Voltage
    6. 3.6 Shutdown Sequence
      1. 3.6.1 1.0-V Input Voltage
      2. 3.6.2 3.0-V Input Voltage

1.2 Considerations

The lab power supply must be connected to the printed-circuit board (PCB). Make this connection with very short cables (≤ 30 cm) to avoid resonances between the output of the lab power supply and the input circuit on the PCB, which can influence the look and results of the frequency analysis.

The copper thickness on the PCB must be a minimum of 70 µm. The tested PCB had 105 µm for the top and bottom layer. Measurements, including efficiency, were taken at room temperature without forced-air cooling.

Unless otherwise indicated:

  • The board was assembled with two low-side FETs (Q2, Q3) and a 330-nH inductor L2
  • The output current was adjusted to 3.0 A

The circuit switches on at 1.10 V and off at about 0.45 V (VEN-Falling level). This individual circuit switches around 200 kHz.

The converter works in continuous conduction mode (CCM) at low input voltage and in discontinuous conduction mode (DCM) at higher input voltage. Under light load conditions the converter was operating in skip mode.

The transfer region DCM to CCM can be seen around:

  • 1 VIN        ⇒ 0.57 AOUT
  • 2 VIN        ⇒ 2.1 AOUT
  • > 2.48 VIN ⇒ 3 AOUT