DCM Buck Converter Loss Calculator

🔌 DCM Buck Converter Loss Calculator

Load Type:

Output Load Current (A):

Enable Burst Mode (Auto):

Input Voltage (V):

Output Voltage (V):

Switching Frequency (kHz):

Inductance (µH):

HS Rds(on) (Ω):

LS Rds(on) (Ω):

HS Coss (pF):

LS Coss (pF):

HS Tr+Tf (ns):

Inductor DCR (Ω):

Inductor Core Loss (mW):

Include Gate Drive Loss:

📝 Overview

This advanced calculator estimates the power losses in a Buck DC-DC Converter operating in Discontinuous Conduction Mode (DCM). It also supports burst mode simulation, which reduces switching losses under light or no-load conditions. This tool is especially useful for engineers and designers working on low-power, battery-sensitive, or space-constrained applications where efficiency across varying load conditions is critical.

⚙️ Key Features

Calculates total power loss in DCM operation.
Supports both normal load and no-load conditions.
Optional burst mode simulation for light-load efficiency modeling.
Provides detailed breakdown of:
- High-Side MOSFET conduction loss
- High-Side MOSFET switching loss
- High/Low-Side Coss (capacitive) switching loss
- Inductor copper loss
- Inductor core loss
Automatically adjusts duty cycle and switching frequency based on input.
Responsive UI with mobile and desktop compatibility.

📊 Inputs Explained

Input Field	Description
Load Type	Choose between “No Load” or “Load Current” mode.
Load Current (A)	Enter the actual output load current in Amps if “Load Current” is selected.
Enable Burst Mode	When checked, burst mode is automatically applied at ≤ 1.5 A.
Input Voltage (V)	DC input voltage to the converter.
Output Voltage (V)	Regulated output voltage of the buck converter.
Switching Frequency (kHz)	Converter’s nominal switching frequency under full load.
Inductance (µH)	Output inductor value.
HS Rds(on) (Ohm)	On-resistance of the high-side switching MOSFET.
HS/LS Coss (pF)	Output capacitance of the high-side and low-side MOSFETs.
HS Tr+Tf (ns)	Total rise and fall time of the HS MOSFET.
Inductor DCR (Ohm)	DC resistance of the output inductor.
Inductor Core Loss (mW)	Estimated magnetic loss in the inductor core.
Gate Drive Loss (Optional)	Gate charge × V_gs × f_sw for switching loss in gate driver stage.

📉 Burst Mode Behavior

When burst mode is enabled:

This significantly reduces switching and conduction losses, which is essential for idle power savings.

The switching frequency is automatically reduced at light loads (≤ 1.5 A), down to as low as 10% of the base frequency.

At no load, both duty cycle and switching frequency are minimized to simulate real-world behavior where the converter enters standby or pulse-skipping mode.

🧮 Core Equations Used

1. Duty Cycle

D=V_out/V_in (automatically calculated)

2. Peak Inductor Current in DCM

I_peak=2⋅I_load/D

Or, in no-load simulation:

I_peak=(V_in⋅D)/(L⋅f_sw)

3. Inductor RMS Current

I_rms=I_peak⋅sqrt(D/3)

4. MOSFET Conduction Loss

P_cond=(D⋅(I_peak)²⋅R_DS(on))/3

5. MOSFET Switching Loss

P_sw=1/2⋅V_in⋅I_peak⋅(t_r+t_f)⋅f_sw

6. Output Capacitance Loss (C_oss)

P_Coss=1/2⋅C_oss⋅V_in²⋅f_sw

7. Inductor Copper Loss

P_copper=I_rms²⋅R_DC

8. Total Loss

P_total=P_cond+P_sw+P_Coss(HS)+P_Coss(LS)+P_copper+P_core

📈 Use Cases for DCM Loss Analysis

Standby power supplies
Pulsed load applications
Low-duty satellite payload converters
Burst-mode switching converters
Low-load industrial IoT nodes
Buck converters with large load variation