Buck Converter

Characterization

Load Regulation & Efficiency

Objective

  1. Evaluate buck’s Vout stability across all load conditions

  2. Measure efficiency across all load conditions

Conditions

  1. Vin = 55V, 44.4V, 36V, 25.2V, 22.2V, 18V

  2. Iout from 0A to 4A with 50 data points (0.08A step)

  3. Set power supply slew rate to minimum

  4. Temperature: room

  5. Use 4-wire sensing on power supply

  6. Don’t use the same wire that goes to eload to measure Vout

Procedure

(scripting)

  1. Solder 1 pair of wires to eload, 1 wire at Vout

  2. Connect DMM to Vout

  3. Connect Power supply to Vin

  4. Turn on power supply

Load Transient

Line Regulation

Output Noise

Common Mode Noise

Inject noise on vbat+ and vbat- using a functional generator, observe buck vin waveform

Start-up behavior

Shut-down behavior

Safety Tests

Over Current

Short Circuit

Over voltage

input voltage surge

Turn on power supply and probe buck vin waveform using oscope, expecting some overshoot on the capture plot

Efuse

Characterization

Start-up

Shut-down

OCP

Short Circuit

PWM Buffer

Characterization

No buffer test

Inject PWM signal at 50% duty cycle at 50Hz

Buffer test

Inject Triangle signal range from 0V to 5V at 50Hz

Inject PWM signal at 50% duty cycle at 50Hz