AnalogySemi Power Management

AnalogySemi offers comprehensive power management solutions including: DC-DC converters (buck, boost, buck-boost) with synchronous rectification for high efficiency, Low-dropout regulators (LDOs) for low-noise applications, Voltage references for precision analog circuits, and Power supervisors for system reset and monitoring. The product range covers input voltages from 2.5V to 60V and output currents from 50mA to 5A, serving applications from battery-powered IoT devices to industrial power supplies.

Choose DC-DC converters for efficiency-critical applications. Choose LDOs for low-noise analog supplies. Choose voltage references for precision measurement circuits.

Choose switching regulators (DC-DC) when: 1) Input-output voltage difference is large (efficiency advantage), 2) Battery life is critical, 3) Heat dissipation is a concern. Choose LDO when: 1) Input-output voltage difference is small (<1V dropout), 2) Low output noise is required (RF, analog circuits), 3) Simple, low-cost solution is preferred, 4) Fast transient response is needed. AnalogySemi offers both options with the ANP series for DC-DC and ANL series for LDOs. Some applications use both: switching regulator for efficient voltage step-down, followed by LDO for clean analog supply.

Use DC-DC for large voltage drops and efficiency. Use LDO for small drops and low noise. Consider cascaded approach for best of both.

Synchronous rectification replaces the Schottky diode in buck converters with a low-RDS(on) MOSFET, significantly reducing conduction losses. Efficiency improvement: 5-15% at heavy loads, especially at low output voltages. For example, a 3.3V output from 12V input: Schottky diode drop (0.4V) is 12% loss, while synchronous MOSFET (50mΩ at 3A = 0.15V drop) is only 4.5% loss. AnalogySemi ANP series buck converters use synchronous rectification to achieve efficiencies up to 95%. The trade-off is slightly higher cost and more complex control, but the efficiency gain is usually worth it for applications above 1W output power.

Use synchronous rectification for applications >1W or when efficiency is critical. Use non-synchronous for lowest cost applications <1W.

LDO power dissipation is calculated as: P_diss = (V_in - V_out) × I_out + V_in × I_quiescent. The first term dominates at moderate to high loads. For example: V_in = 5V, V_out = 3.3V, I_out = 200mA, I_q = 50μA. P_diss = (5 - 3.3) × 0.2 + 5 × 0.00005 = 0.34W + 0.00025W ≈ 0.34W. Junction temperature: T_j = T_a + P_diss × θ_ja. With T_a = 50°C and θ_ja = 50°C/W: T_j = 50 + 0.34 × 50 = 67°C. For reliable operation, keep T_j below 125°C. High input-output differential with high current can cause excessive heating - consider switching regulators for these cases.

Calculate dissipation before selecting LDO. Ensure T_j stays below 125°C. Use switching regulator for large voltage drops with high current.

PSRR (Power Supply Rejection Ratio) measures how well an LDO rejects input voltage variations from appearing at the output. It's expressed in dB - higher is better. For example, 60dB PSRR means input ripple is attenuated by 1000x. PSRR varies with frequency, typically highest at low frequencies (50-80dB at 100Hz) and decreasing at higher frequencies (20-40dB at 100kHz). High PSRR is critical for: 1) Analog circuits (ADCs, amplifiers) sensitive to supply noise, 2) RF circuits where supply noise can modulate the carrier, 3) Precision measurement systems. AnalogySemi ANL series LDOs offer PSRR up to 80dB at 1kHz, making them suitable for sensitive analog applications.

Select LDOs with PSRR >60dB at frequencies present in your system. Check PSRR curve, not just single point specification.