Documentation sections

Boost Converter Design Calculator

POSThttps://rftools.io/api/py/v1/calculate

Slug boost-converter. Calculate duty cycle, inductor value, and output capacitor for boost (step-up) DC-DC converter design

Inputs

Send every one of these in inputs, in the units shown. Most are required: a call without one is refused (400) and costs nothing; one the calculator can do without takes the default shown. An input outside its range is still computed and flagged in the provenance.

Inputs of boost-converter
Name	Unit	Range	Default	Description
inputVoltagenumber	V	at least 0.5	5	Input Voltage
outputVoltagenumber	V	at least 1	12	Output Voltage
outputCurrentnumber	A	at least 0.01	0.5	Output Current
switchFreqnumber	kHz	at least 1	100	Switching Frequency
ripplePctnumber	%	5 … 80	30	Inductor current ripple as % of average inductor current
efficiencynumber	%	50 … 99	88	Estimated Efficiency
inputVoltageMinnumber	V	at least 0	0	The lowest input the converter must work from; 0 for the nominal. The parts are sized and the stresses taken over the range.
inputVoltageMaxnumber	V	at least 0	0	The highest input the converter must work from; 0 for the nominal. It must stay below the output.
coutEachnumber	μF	0.1 … 10000	10	One output capacitor; the bank is as many in parallel as the 5 % ripple target needs at the worst corner.
rdsOnnumber	mΩ	0.1 … 10000	25	The switch FET's on-resistance at its operating temperature.
tSwitchnumber	ns	0 … 10000	20	The switch's rise and fall times added: the switching loss is ½·V_out·I_L·(t_r + t_f)·f_sw.
qgnumber	nC	0 … 10000	10	The switch's gate charge at the drive voltage: the gate drive takes Q_g·V_g·f_sw.
vGatenumber	V	1 … 20	5	Gate Drive Voltage
vDiodenumber	V	0 … 3	0.45	The rectifier diode's forward voltage at the load current: it dissipates V_F·I_out.
qrrnumber	nC	0 … 10000	0	The rectifier's reverse-recovery charge (a Schottky's is its capacitive charge, near 0): the switch takes Q_rr·V_out at each turn-on, Q_rr·V_out·f_sw in all.
dcrnumber	mΩ	0 … 100000	50	The inductor's winding resistance.
coreLossnumber	mW	0 … 100000	20	From the inductor's datasheet at this ripple and frequency.
esrOutnumber	mΩ	0 … 100000	5	Output Capacitor ESR (each)

Outputs

Returned in values, by key. A value that is unbounded or undefined is null.

Outputs of boost-converter
Field	Unit	Description
dutyCycle	%	Duty Cycle
inductorCurrent	A	Average Inductor Current
inductorValueheadline	μH	Inductor Value
outputCapacitor	μF	Output Capacitor
peakCurrent	A	Peak Inductor Current
dutyMin	%	At the maximum input voltage
dutyMax	%	At the minimum input voltage
inductorMinWorstUH	μH	For the ripple target where it needs the most inductance: at ⅔·V_out/η when the range spans it, otherwise at an end
inductorChosenUH	μH	The E12 value at or above the minimum inductance; every current below is the chosen part's
rippleNomA	A	Peak to peak, at the nominal input, with the chosen inductor
rippleWorstA	A	The largest at the corners of the input range; the ripple itself peaks at V_out/(2·η), and a warning gives it when the range spans that
rippleWorstVin	V	Input at the Worst Ripple
ilPeakWorst	A	The peak the inductor, the switch and the rectifier carry; the inductor's saturation current must be at least this
ilPeakWorstVin	V	Input at the Worst Peak
inputCurrentWorst	A	The average inductor (input) current, largest at the minimum input
inputCurrentWorstVin	V	Input at the Worst Input Current
q1RmsA	A	Switch RMS Current, Worst Case
q1RmsVin	V	Input at the Worst Switch Current
coutMinWorstUF	μF	For today's 5 % ripple target at the worst corner, the minimum input
coutCount	none	How many of the chosen output capacitor, in parallel
coutTotalUF	μF	Output Capacitance (bank)
coutRmsA	A	The AC part of the rectifier current, shared by the bank
coutRmsVin	V	Input at the Worst Output Capacitor Current
outputRippleMV	mV	Peak to peak: the bank's charge ripple plus its ESR step at the peak current, added (an upper bound)
outputRippleVin	V	Input at the Worst Output Ripple
outputRipplePct	%	Output Ripple, % of Vout
vdsRating	V	The rating sold at or above 1.5 times the output, which the switch blocks when off and the rectifier when the switch is on
coutVoltageRating	V	The rating sold at or above 1.5 times the output
lossSwConduction	W	Switch Conduction Loss
lossSwSwitching	W	Switch Switching Loss
lossGateDrive	W	Gate Drive Loss
lossDiode	W	Rectifier Conduction Loss
lossRecovery	W	Rectifier Recovery Loss
lossDcr	W	Inductor DCR Loss
lossCore	W	Inductor Core Loss
lossCapEsr	W	Output Capacitor ESR Loss
lossTotal	W	Total Loss
outputPower	W	Output Power
efficiencyLossModel	%	At the nominal input and load, from the loss model. The currents are sized with the estimated efficiency input; set it to this value and they follow the loss model

Calling it

Calculate: one call, the request and response in full, and its errors.
Batch: this calculator with others, or a sweep, in one request.
Solve for a target: the value of one input that brings an output to a target.

curl -X POST https://rftools.io/api/py/v1/calculate \
  -H "X-API-Key: $RFTOOLS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "slug": "boost-converter",
    "inputs": {
      "inputVoltage": 5,
      "outputVoltage": 12,
      "outputCurrent": 0.5,
      "switchFreq": 100,
      "ripplePct": 30,
      "efficiency": 88,
      "inputVoltageMin": 0,
      "inputVoltageMax": 0,
      "coutEach": 10,
      "rdsOn": 25,
      "tSwitch": 20,
      "qg": 10,
      "vGate": 5,
      "vDiode": 0.45,
      "qrr": 0,
      "dcr": 50,
      "coreLoss": 20,
      "esrOut": 5
    }
  }'

import rftools

client = rftools.Client()  # reads RFTOOLS_API_KEY, or the key `rftools login` saved

result = client.calculate("boost-converter", {
    "inputVoltage": 5,
    "outputVoltage": 12,
    "outputCurrent": 0.5,
    "switchFreq": 100,
    "ripplePct": 30,
    "efficiency": 88,
    "inputVoltageMin": 0,
    "inputVoltageMax": 0,
    "coutEach": 10,
    "rdsOn": 25,
    "tSwitch": 20,
    "qg": 10,
    "vGate": 5,
    "vDiode": 0.45,
    "qrr": 0,
    "dcr": 50,
    "coreLoss": 20,
    "esrOut": 5,
})
print(result.values)
print(result.warnings, result.provenance.formula_ref)

const response = await fetch("https://rftools.io/api/py/v1/calculate", {
  method: "POST",
  headers: {
    "X-API-Key": process.env.RFTOOLS_API_KEY,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "slug": "boost-converter",
    "inputs": {
      "inputVoltage": 5,
      "outputVoltage": 12,
      "outputCurrent": 0.5,
      "switchFreq": 100,
      "ripplePct": 30,
      "efficiency": 88,
      "inputVoltageMin": 0,
      "inputVoltageMax": 0,
      "coutEach": 10,
      "rdsOn": 25,
      "tSwitch": 20,
      "qg": 10,
      "vGate": 5,
      "vDiode": 0.45,
      "qrr": 0,
      "dcr": 50,
      "coreLoss": 20,
      "esrOut": 5
    }
  }),
});
console.log(response.status, await response.json());

package main

import (
	"bytes"
	"fmt"
	"io"
	"net/http"
	"os"
)

func main() {
	body := []byte(`{
	  "slug": "boost-converter",
	  "inputs": {
	    "inputVoltage": 5,
	    "outputVoltage": 12,
	    "outputCurrent": 0.5,
	    "switchFreq": 100,
	    "ripplePct": 30,
	    "efficiency": 88,
	    "inputVoltageMin": 0,
	    "inputVoltageMax": 0,
	    "coutEach": 10,
	    "rdsOn": 25,
	    "tSwitch": 20,
	    "qg": 10,
	    "vGate": 5,
	    "vDiode": 0.45,
	    "qrr": 0,
	    "dcr": 50,
	    "coreLoss": 20,
	    "esrOut": 5
	  }
	}`)
	req, err := http.NewRequest("POST", "https://rftools.io/api/py/v1/calculate", bytes.NewReader(body))
	if err != nil {
		panic(err)
	}
	req.Header.Set("X-API-Key", os.Getenv("RFTOOLS_API_KEY"))
	req.Header.Set("Content-Type", "application/json")
	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()
	out, _ := io.ReadAll(res.Body)
	fmt.Println(res.Status, string(out))
}

application/json

{
  "slug": "boost-converter",
  "values": {
    "dutyCycle": 63.33333333333333,
    "inductorCurrent": 1.3636363636363635,
    "inductorValue": 77.4074074074074,
    "outputCapacitor": 5.277777777777777,
    "peakCurrent": 1.5681818181818181,
    "dutyMin": 63.33333333333333,
    "dutyMax": 63.33333333333333,
    "inductorMinWorstUH": 77.4074074074074,
    "inductorChosenUH": 82,
    "rippleNomA": 0.3861788617886179,
    "rippleWorstA": 0.3861788617886179,
    "rippleWorstVin": 5,
    "ilPeakWorst": 1.5567257945306725,
    "ilPeakWorstVin": 5,
    "inputCurrentWorst": 1.3636363636363635,
    "inputCurrentWorstVin": 5,
    "q1RmsA": 1.08883282348745,
    "q1RmsVin": 5,
    "coutMinWorstUF": 5.277777777777777,
    "coutCount": 1,
    "coutTotalUF": 10,
    "coutRmsA": 0.6605869038227407,
    "coutRmsVin": 5,
    "outputRippleMV": 324.4502956393201,
    "outputRippleVin": 5,
    "outputRipplePct": 2.703752463661001,
    "vdsRating": 20,
    "coutVoltageRating": 25,
    "lossSwConduction": 0.02963892293759132,
    "lossSwSwitching": 0.016363636363636365,
    "lossGateDrive": 0.005,
    "lossDiode": 0.225,
    "lossRecovery": 0,
    "lossDcr": 0.09359659875028838,
    "lossCore": 0.02,
    "lossCapEsr": 0.0021818752875105737,
    "lossTotal": 0.39178103333902664,
    "outputPower": 6,
    "efficiencyLossModel": 93.87054983117339
  },
  "warnings": [],
  "errors": [],
  "provenance": {
    "method": "calculator:boost-converter",
    "version": "api@3f2c1a9b04de",
    "formulaRef": "TI SLVA372D, Basic Calculation of a Boost Converter's Power Stage, eq. 1; Erickson & Maksimovic, \"Fundamentals of Power Electronics\" 3rd ed.",
    "assumptions": [],
    "validRange": {
      "status": "inside",
      "bounds": {
        "inputVoltage": {
          "min": 0.5,
          "max": null,
          "unit": "V"
        },
        "outputVoltage": {
          "min": 1,
          "max": null,
          "unit": "V"
        },
        "outputCurrent": {
          "min": 0.01,
          "max": null,
          "unit": "A"
        },
        "switchFreq": {
          "min": 1,
          "max": null,
          "unit": "kHz"
        },
        "ripplePct": {
          "min": 5,
          "max": 80,
          "unit": "%"
        },
        "efficiency": {
          "min": 50,
          "max": 99,
          "unit": "%"
        },
        "inputVoltageMin": {
          "min": 0,
          "max": null,
          "unit": "V"
        },
        "inputVoltageMax": {
          "min": 0,
          "max": null,
          "unit": "V"
        },
        "coutEach": {
          "min": 0.1,
          "max": 10000,
          "unit": "μF"
        },
        "rdsOn": {
          "min": 0.1,
          "max": 10000,
          "unit": "mΩ"
        },
        "tSwitch": {
          "min": 0,
          "max": 10000,
          "unit": "ns"
        },
        "qg": {
          "min": 0,
          "max": 10000,
          "unit": "nC"
        },
        "vGate": {
          "min": 1,
          "max": 20,
          "unit": "V"
        },
        "vDiode": {
          "min": 0,
          "max": 3,
          "unit": "V"
        },
        "qrr": {
          "min": 0,
          "max": 10000,
          "unit": "nC"
        },
        "dcr": {
          "min": 0,
          "max": 100000,
          "unit": "mΩ"
        },
        "coreLoss": {
          "min": 0,
          "max": 100000,
          "unit": "mW"
        },
        "esrOut": {
          "min": 0,
          "max": 100000,
          "unit": "mΩ"
        }
      },
      "outside": [],
      "model": null
    },
    "computedAt": "2026-09-24T14:05:11.003Z",
    "inputs": {
      "inputVoltage": 5,
      "outputVoltage": 12,
      "outputCurrent": 0.5,
      "switchFreq": 100,
      "ripplePct": 30,
      "efficiency": 88,
      "inputVoltageMin": 0,
      "inputVoltageMax": 0,
      "coutEach": 10,
      "rdsOn": 25,
      "tSwitch": 20,
      "qg": 10,
      "vGate": 5,
      "vDiode": 0.45,
      "qrr": 0,
      "dcr": 50,
      "coreLoss": 20,
      "esrOut": 5
    },
    "seed": null,
    "elapsedSeconds": 0.003
  }
}

{
  "detail": [
    {
      "type": "float_parsing",
      "loc": [
        "body",
        "inputs",
        "inputVoltage"
      ],
      "msg": "Input should be a valid number, unable to parse string as a number",
      "input": "abc"
    }
  ]
}

An input sent as text. Nothing was counted.

{
  "detail": "More than 120 requests in 60 seconds from this address.",
  "errorKind": "rate_limited",
  "limit": 120,
  "windowSeconds": 60,
  "upgradeUrl": "https://rftools.io/pricing/"
}

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Same inputs on the calculator pageBoost Converter Design Calculator, at these values