Power Management IC Selection Guide: LDOs, DC-DC, PMICs, GaN Drivers

Power Management IC Selection Guide: LDOs, DC-DC Converters, PMICs, and GaN Drivers

Every board runs on power management ICs. Get the choice wrong and you'll see it soon enough — an overheated corner, a battery that dies early, noise bleeding into your analog section. We've traced plenty of those symptoms back to the regulator itself.

PMIC Categories

Linear Regulators (LDOs)

When to use: Low current (<500mA), low dropout, noise-sensitive circuits

Key specs: Dropout voltage, PSRR (Power Supply Rejection Ratio)

Advanced: Some LDOs have a "power good" output flag

Popular parts:

• TI TPS7A47 (ultra-low noise, 36V input, 1A)
• AMS1117-3.3 (budget, 1A)
• LP2985 (micropower, 150mA)

Chinese alternatives: 3PEAK TP2111, SGMicro SGM2036

DC-DC Buck Converters

When to use: Step-down where efficiency matters (>85% target)

Key specs: Switching frequency, Iq (quiescent current), efficiency at light load

Popular parts:

• TI TPS54302 (4.5-28V, 3A, synchronous)
• MP1584 (4.5-28V, 3A, budget Switcher)
• AP63205 (2.3-5.5V, 2A)

Chinese alternatives: MPS (Monolithic Power, US-listed but China R&D), Silergy SY series

DC-DC Boost Converters

When to use: Step-up (battery → 5V/12V), LED backlight, USB OTG

Key specs: True output disconnect, start-up voltage

Popular parts:

• TI TPS61088 (2.7-12V → up to 12.6V, 10A switch)
• MT3608 (budget, 28V max)

PMICs (Power Management ICs)

Multi-rail chips that combine bucks, LDOs, and sequencing in one package. Once the design crosses three rails, we usually go straight to one of these instead of hand-stitching discrete converters.

When to use: Any design with 3+ voltage rails

Key advantage: Power sequencing is handled internally

Popular parts:

• TI TPS65217 (AM335x companion PMIC)
• NXP PF Series (i.MX companion PMICs)
• Rockchip RK805/RK808 (Rockchip companion PMICs)

GaN Gate Drivers

GaN FETs require specialized gate drivers:

• E-mode GaN: Similar to MOSFET drivers but with tighter voltage tolerance (4.5-6V typical)
• Cascode GaN: Can use standard MOSFET drivers
• Isolated drivers needed for high-side switches

Popular parts:

• TI LMG1020 (5V, 7A, sub-ns propagation delay)
• Navitas NV6117 (integrated GaN + driver)

PMIC Selection Checklist

1. Input voltage range (including transients, add 20% margin)
2. Output current per rail (peak, not average)
3. Sequencing requirements (who powers up/down first?)
4. Efficiency targets (battery vs wall-powered?)
5. EMI constraints (switching frequency placement)
6. Thermal budget (η = 90% means 10% of power becomes heat)
7. Package and footprint (QFN vs BGA vs module)

References

• TI Power Management Guides
• IEEE Power Electronics