Real world efficiency of a LM3150 Webench DC power supply design?
Using a National Semiconductor LM3150 evaluation board the real world measured apparent power (S in VA) efficiency is:

Sη = 97.71% @8.00A load

The TI evaluation PCB might be designed as generic board for different voltages and not be as efficient as possible. That is why an optimised 5x5cm LM3150 PCB was designed for only a 12VDC to 5VDC conversion. The active power (P in Watts) efficiency measured using different measuring instruments, see measurement setup #2.

Pη = 97.65% @8.00A load

Using an optimized PCB layout, efficiency results improved:

Pη = 98.25% @8.00A load


More load versus active power efficiency results [PCB rev.1; rev.2]:


0.800A = 95,73%; 96,00%
1.000A = 96,12%; 96,38%
1.600A = 96,13%; n/a
3.200A = 97,51%; n/a
4.800A = 98,17%; 98,31%
8.000A = 97,65%; 98,25%
10.00A = 97,21%; 98,08%
12.00A = n/a; 97,89%
13.00A = n/a; 97,80%




Measurement setup #1


Iout: 8.00A (8A load)
Vout: 5.04V
Pout: 40.32W
Iin: 3.50A
Vin: 11.79V
Pin: 41.265W


Device specifications


Electronic load: Maynuo M9812 constant current mode; resolution 1 mA; accuracy 0.03% + 0.05% FS
Power supply: Troniq PSU303DX2
Multimeter (M1 current): Fluke 87 resolution 1mA; accuracy ±(0.2% + 2)
Multimeter (M2 voltage): Fluke 17B resolution 0.01 V; accuracy ±(0.5% + 3)


Power after measurement faults


Pin max: 41.55W
Pin min: 40.98W
Pout max: 40.53W
Pout min: 40.11W


Efficiency after measurement faults


Minimum efficiency: 96.52%
Maximum efficiency: 98.92%


Measurement setup #2

Device specifications for alternative PCB measurement:


Electronic load: Itech 8512+ a.k.a. IT8512A+ constant current mode
Power supply: Owon ODP 3032 parallel setup; constant voltage mode
Power meter: Zes Zimmer LMG95 measure cycle: 50ms; filter: off; S-Cpl: AC+DC; internal shunt; accuracy 0.03% + 0.03% of measuring range
Temperature: 21~25ºC
Cable length from PCB to load and PCB to power supply: 0,4 meter each
Cable type: stranded copper wire, diameter 1,66 mm




To see whether components matter we also compared a Webench LM2743 electronics reference design for a 12 to 5VDC power supply (including an inefficient LM2937 linear voltage regulator). The LM2743 was build in two versions of ceramic capacitors for CIN, COUTREG:


Murata GRM32ER61E226KE15L each € 1.51 => 90.90% efficient
TDK C3225X5R1E226K250AC each € 0.83 => 91.89% efficient


Conclusion: capacitors from different brands behave different.



Component specification for the LM3150 PCB:


Cff = GRM2165C1H202JA01D
Css = GRM21BR72A153KA01L
M1, M2 = CSD16321Q5
Rilim = CRCW0805332RFKEA
Ron = ERJ-6ENF4643V
Cvcc = EMK212B7225KG-T
Cbst = EMK212B7474KD-T
Rfb1 = ERJ-6ENF1002V
Cbyp = 08053C104KAT2A
Rrb2 = ERJ-6ENF7322V
Cin = GRM32ER61E226KE15L
Cout = 16SVP330M
U1 = LM3150MHX/NOPB
L1 = SER2915L-103KL
PCB = 551600142-002/NOPB