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AN268 PWM Amplifier Output Power Calculator

The PWM amplifier output power calculator is used to determine the effective root mean square (rms) power for a given speaker load. The spreadsheet is configured to calculate the actual power delivered to the speaker load for three typical speaker-load configurations, half-bridge tied, full-bridge tied and parallel full-bridge tied. For more details, please view the Application Note.

Assumptions

Voltage Rail Vp (volts)
Modulation Index
PWM Output Rds_on (ohms)
Capacitor ESR (ohms)
Inductor Resistance (ohms)

Calculations
Speaker Load (ohms)
Power Out (Wrms)
Total Current (lrms)
Total Current (lpeak)
Power at the Load (Wrms)
0.1% THD+N
1% THD+N(x1.15)
10% THD+N(x1.75)
Efficiency
Power Dissipation (Wrms) per channel
Speaker Load (ohms)
Power Out (Wrms)
Total Current (lrms)
Total Current (lpeak)
Power at the Load (Wrms)
0.1% THD+N
1% THD+N(x1.15)
10% THD+N(x1.75)
Efficiency
Power Dissipation (Wrms) per channel
Speaker Load (ohms)
Power Out (Wrms)
Total Current (lrms)
Total Current (lpeak)
Power at the Load (Wrms)
0.1% THD+N
1% THD+N(x1.15)
10% THD+N(x1.75)
Efficiency
Power Dissipation (Wrms) per channel