Synchronous or diode buck power stage: duty cycle, inductor and capacitor sizing, output ripple, full loss breakdown, junction temperatures and efficiency
Operating Point
V
V
V
A
kHz
ns
°C
Inductor
µH
mΩ
A
Capacitors
µF
mΩ
mV
A
%
µF
High-Side FET
mΩ
nC
nC
pF
Low-Side FET
mΩ
nC
Thermal
°C
°C/W
°C/W
Design looks good
Safe
94.7
Efficiency (%)
65.1
Hottest Tj, HS @ Vin,max (°C)
4.61
Worst-Case Ripple (mVpp)
Results
Duty & Timing
Duty Cycle28.31%
On-Time566ns
On-Time at Vin,max?515ns
Pulse-Skip fsw Limit?2.57MHz
HS Turn-On Transition?4.55ns
HS Turn-Off Transition?3.57ns
Input Current1.45A
Inductor
Inductance4.70µH
Ripple Current1.03A
Ripple Ratio20.7%
Peak Current5.52A
Valley Current4.48A
RMS Current5.01A
Ripple Current at Vin,max?1.07A
Peak Current at Vin,max?5.54A
DCM Boundary Load?517mA
Output Capacitor
Output Ripple?4.37mV
Ripple, Linear Sum?6.96mV
Ripple at Vin,max4.61mV
Min Cout, Load Step?60.6µF
Min Cout, Unload Overshoot?78.9µF
Min Cout, Ripple?8.93µF
Max ESR for Ripple?28.0mΩ
Cout RMS Current at Vin?298mA
Cout RMS Current at Vin,max?309mA
Thermal
HS Junction Temperature64.2°C
LS Junction Temperature57.4°C
HS Dissipation354mW
LS Dissipation184mW
HS Rds(on) at Tj12.0mΩ
LS Rds(on) at Tj5.81mΩ
HS Junction at Vin,max?65.1°C
LS Junction at Vin,max?57.5°C
HS Dissipation at Vin,max377mW
LS Dissipation at Vin,max?188mW
Input Capacitor & Power
Cin RMS Current?2.26A
Input Ripple118mV
Output Power16.5W
Total Loss930mW
Efficiency vs Load
At Vin
At Vin,max
Loss Breakdown
Conduction (FET / diode drop)
Switching & gate drive
Inductor DCR
Capacitor ESR
At Io = 5.00 Atotal 930 mW
Inductor DCR301 mW32%
HS switching (V·I)120 mW13%
Reverse recovery120 mW13%
LS conduction104 mW11%
HS conduction84.9 mW9%
Dead-time diode80.0 mW9%
Gate drive75.0 mW8%
Coss28.8 mW3%
Cin ESR15.3 mW2%
Cout ESR267 µW0%
Switching Waveforms
iL at Vin
iL at Vin,max
ΔIL 1.03 Apk 5.52 Avalley 4.48 Apk at Vin,max 5.54 A