Similar to transformers but for direct current, DC-DC converters adjust voltage levels while maintaining impedance. These devices don't generate power but transform input energy, with modern units achieving up to 90% efficiency. They accommodate various voltages, from small batteries to power transmission systems.

Key Concepts in DC-DC Power Supplies

Modern integrated circuits allow higher switching frequencies, enabling smaller magnetic components and faster response times. Wide bandgap semiconductors like SiC and GaN further enhance performance with lower losses.

Common converter types include:

• Buck converters (step-down)
• Boost converters (step-up)
• Buck-boost converters (adjustable output)
• Flyback converters (isolated designs)

Selection depends on application requirements balancing performance, size, and cost.

Coil Selection Guidelines

Refer to inductance charts based on frequency and load current. Lower DC resistance improves performance, while proper current ratings prevent overheating and saturation.

Inductance Value Selection Load 50kHz 100kHz 180kHz 300kHz 500kHz Light Load 330μH 220μH 100μH 47μH 22μH Medium Load 220μH 100μH 47μH 22μH 10μH Heavy Load 100μH 47μH 22μH 10μH 6.8μH

Diode Selection

Choose diodes with low forward voltage (under 0.6V) and minimal capacitance to reduce losses and noise. Current ratings should exceed peak coil currents.

Load Capacitance

Consider temperature effects on ceramic capacitors. Tantalum capacitors (10-100µF) with proper ESR (0.1-0.5Ω) ensure stable operation.

Input Capacitors

Place input capacitors close to ICs for effective ripple reduction. Low ESR types are recommended for step-down converters.

External Transistors

MOSFETs with low ON resistance are preferred, except for sub