What Is the Buck-Boost Inverting DC-DC Converter Calculator?
The Buck-Boost Inverting DC-DC Converter Calculator designs negative rail power supplies for analog instrumentation and audio circuits.
How Does the Buck-Boost Inverting DC-DC Converter Calculator Work?
It computes the required duty cycle accounting for conversion losses and sizes magnetic inductors and output filter capacitors for continuous conduction.
Buck-Boost Inverting DC-DC Converter Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
D = \frac{|V_{out}|}{|V_{out}| + V_{in}\eta}, \quad I_{L,avg} = \frac{I_{out}}{1 - D}, \quad L = \frac{V_{in} D}{\Delta I_L f_{sw}}
Steady-state volt-second balance and capacitor charge balance for inverting topology.
How to Use the Buck-Boost Inverting DC-DC Converter Calculator
- Enter input voltage and target negative output voltage magnitude.
- Specify maximum load current and switcher frequency.
- Set inductor current ripple ratio (30% is standard).
Step-by-Step Example Calculation
+12V to -15V at 2A Industrial Inverting Converter
Input Values:
inputVoltageVin:12
outputVoltageVoutMag:15
loadCurrentIout:2
switchingFrequencyKhz:150
targetCurrentRipplePercent:30
efficiencyEstimatePercent:85
Worked Steps: Requires a 59.5% duty cycle, 4.94 A average inductor current, 27.2 µH power inductor, and 39.7 µF output capacitor.
Understanding Your Result
Power Inductor (L): Recommended inductance in µH.
Duty Cycle (D): Operational PWM duty ratio.
Peak Switch Current: Maximum current rating for MOSFET switch.
Factors That Affect the Result
- Higher switching frequencies enable proportionally smaller inductors and capacitors at the expense of higher switching losses.
When Should You Use This Calculator?
- Dual ±12V or ±15V op-amp supplies, RF power amplifier negative gate bias, and battery-powered portable instrumentation.
Assumptions & Limitations
- Assumes steady-state continuous conduction mode (CCM) operation.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Standard power electronics design principles per Erickson & Maksimovic.