SLVU735A June   2012  – February 2022 TPS51225

 

  1.   Trademarks
  2. 1 Description
    1. 1.1 Typical Applications
    2. 1.2 Features
  3. 2 Electrical Performance Specifications
  4. 3 Schematic
  5. 4 Test Setup
    1. 4.1 Test Equipment
    2. 4.2 Recommended Test Setup
  6. 5 Configurations
  7. 6 Test Procedure
    1. 6.1 Line/Load Regulation and Efficiency Measurement Procedure
    2. 6.2 List of Test Points
    3. 6.3 Equipment Shutdown
  8. 7 Performance Data and Typical Characteristic Curves
    1. 7.1  5-V Efficiency
    2. 7.2  5-V Load Regulation
    3. 7.3  3.3-V Efficiency
    4. 7.4  3.3-V Load Regulation
    5. 7.5  Enable Turn-On/Turn-Off
    6. 7.6  Output Ripple
    7. 7.7  Switching Node
    8. 7.8  5-V Output Transient with Auto-skip Mode
    9. 7.9  3.3-V Output Transient with Auto-skip Mode
    10. 7.10 Output Prebias Turn-On
    11. 7.11 Thermal Image
  9. 8 EVM Assembly Drawing and PCB Layout
  10. 9 Bill of Materials
  11. 10Revision History

4.1 Test Equipment

Voltage Source: The input voltage, VIN, should be a 0-V to 20-V variable DC source capable of supplying 10 ADC. Connect VIN to J1 as shown in Figure 4-2.

Multimeters:

  • V1: VIN at TP1 (VIN) and TP6 (GND)
  • V2: Vout1 at TP2 (Vout1) and TP7 (GND)
  • V3: Vout2 at TP3 (Vout2) and TP8 (GND)
  • A1: VIN input current

Output Load: The output load should be an electronic constant resistance mode load capable of 0 ADC to 15 ADC.

Oscilloscope: A digital or analog oscilloscope can measure the output ripple. Set the oscilloscope for the following:

  • 1-MΩ impedance
  • 20-MHz bandwidth
  • AC coupling
  • 4-µs/division horizontal resolution
  • 50-mV/division vertical resolution

Use test points TP2 (Vout1), TP3 (Vout2), TP7 (GND), and TP8 (GND) for measuring the output ripple voltage by placing the oscilloscope probe tip through TP2/TP3 and holding the ground barrel on TP7/TP8 as shown in Figure 4-1. Using a leaded ground connection can induce additional noise due to the large ground loop.

GUID-908B7957-D859-4C22-A801-96D76E25DCCD-low.gifFigure 4-1 Tip and Barrel Measurement for VOUT Ripple

Fan: Some of the components in this EVM can approach temperatures of 60°C during operation. A small fan capable of 200–400 linear feet per minute (LFM) is recommended to reduce component temperatures while the EVM is operating. Do not probe the EVM while the fan is not running.

Recommended Wire Gauge:

  1. VIN to J1(12-V input):
    The recommended wire size is 1× American wire gauge (AWG) #14 per input connection, with the total length of wire less than four feet (2-feet input, 2-feet return).
  2. J2, J3 to Load1, Load2:
    The minimum recommended wire size is AWG #14, with the total length of wire less than four feet (2-feet output, 2-feet return).