Linco (Linko Semiconductor) Power Management ICs

LDO vs DC-DC selection criteria: (1) Voltage difference - small dropout (<2V) use LDO, large difference use DC-DC

(2) Efficiency - LDO efficiency = Vout/Vin, DC-DC typically 85-95%

(3) Noise sensitivity - LDO has lower noise, better for analog/RF

(4) Current - high current (>500mA) favors DC-DC efficiency

(5) Cost - LDO simpler and cheaper

(6) EMI - LDO generates no EMI, DC-DC requires filtering. For motor control: use LDO for MCU supply (low current, needs clean power), use DC-DC for power stage (high current, efficiency critical). Many designs use both - DC-DC for main conversion, LDO post-regulation for sensitive circuits.

Use LDO for low current, low noise, small dropout. Use DC-DC for high current, large voltage difference.

LDO dropout voltage explained: (1) Definition - minimum voltage difference between input and output for regulation, typically 200mV-1V

(2) Importance - determines minimum input voltage for desired output

example: 3.3V output with 500mV dropout requires 3.8V minimum input

(3) Factors - dropout depends on load current and LDO design, PMOS LDOs have lower dropout than NMOS

(4) Headroom - always maintain margin above dropout for line transient response

(5) Battery applications - low dropout critical for maximizing battery life. Linco LDOs feature low dropout (200-500mV) for efficient operation. Check dropout vs load current curves in datasheet.

Ensure Vin > Vout + dropout + margin. Select low dropout for battery or tight voltage applications.

LDO power dissipation calculation: (1) Formula - Pd = (Vin - Vout) × Iout

(2) Example - 12V to 5V at 100mA: (12-5) × 0.1 = 0.7W

(3) Thermal - Tj = Ta + Pd × Theta-JA, must keep Tj < maximum rating

(4) Efficiency - Pout/Pin = Vout/Vin, 5V/12V = 42% in example

(5) Heat sinking - may need copper area or heatsink for high dissipation. LDOs are inefficient when Vin >> Vout. For high current or large voltage differences, use DC-DC converter instead. Calculate worst-case dissipation at maximum Vin and Iout. If Tj exceeds rating, reduce load, lower Vin, add heat sinking, or switch to DC-DC.

Calculate Pd = (Vin-Vout)×Iout. Ensure Tj < Tmax. Use DC-DC if dissipation too high.

Linco PMIC protection features: (1) Overcurrent Protection (OCP) - limits output current during short circuit or overload

(2) Overvoltage Protection (OVP) - prevents output voltage exceeding safe levels

(3) Undervoltage Lockout (UVLO) - disables output when input too low

(4) Thermal Shutdown - turns off at overtemperature, auto-restarts when cooled

(5) Soft-start - gradual output ramp prevents inrush current

(6) Reverse Current Protection - prevents damage from reverse polarity. These protections ensure reliable operation and prevent damage during fault conditions. Automotive-grade PMICs have enhanced protection and diagnostics.

All Linco PMICs include comprehensive protection. Select automotive grade for enhanced reliability.

Output capacitor selection guidelines: (1) Capacitance - larger value improves transient response and stability, typical 10-100uF

(2) ESR - low ESR ceramic preferred for LDOs, critical for stability

(3) Type - X5R/X7R ceramic for low ESR, tantalum or electrolytic for bulk capacitance

(4) Voltage rating - 2× output voltage minimum

(5) Placement - close to output pins with short traces

(6) Temperature - X7R better than X5R for high temperature. Output capacitor affects stability, transient response, and noise. Insufficient capacitance causes oscillation and poor load transient response. Follow datasheet recommendations for minimum capacitance and ESR.

Use 22uF X7R ceramic minimum. Place close to output pins. Check datasheet for specific requirements.