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https://docs.espressif.com/projects/esp-hardware-design-guidelines/en/latest/esp32c3/pcb-layout-design.html#pcb-layout-design

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Bring-up & Validation

It’s been a while since the design of this board was completed.

Theoretical Efficiency CalculationTheoretical Efficiency Calculation

Calculating Efficiency (Rev. A)

There are multiple significant sources of loss in a buck converter:

• Inductor losses from ESR

• MOSFET losses from R_{DS_ON} (the “ESR” or DCR from drain to source)

• MOSFET switching losses (relevant in SMPS due to rapid switching)

Inductor Loss

This board uses a 1.8uH powder-core inductor from Bourns called the SRP7028A, with an ESR of 17mOhm. Using the root-mean-square load current value flowing from the switch node on the IC to the inductor, we can use P_LOSS = (I_RMS²) x (R_DCR)_{to calculate power loss. Under full load:}

P_LOSS = (4 Amps)² x (17 mOhm) = 27.2 mW

MOSFET Conduction Loss

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For the high-side MOSFET (controlling the input path during a rise in current) and the low-side MOSFET (the equivalent of the diode in an asynchronous buck converter, conducting when the high-side input switch is off), the TPS564247 gives R_DS(ON) values.

P_LOSS =