Linco (Linko Semiconductor) Gate Drivers

Gate drive current selection depends on MOSFET characteristics: (1) Gate charge (Qg) - total gate charge from datasheet, typically 10-200nC

(2) Switching time - desired rise/fall time, typically 50-200ns

(3) Calculation - Igate = Qg / trise

example: 100nC / 100ns = 1A drive current

(4) Margin - select driver with 20-50% more current than calculated

(5) Frequency - higher PWM frequencies need faster switching. For small MOSFETs (Qg < 50nC), 0.5A drivers suffice. For large MOSFETs (Qg > 100nC), 1A+ drivers are needed. Linco offers 0.5A, 1A, and 2A drive options to match different MOSFET requirements.

Calculate required current from Qg and desired switching time. Add 20-50% margin.

Shoot-through protection prevents destructive current flow: (1) Problem - in half-bridge, both high and low side MOSFETs conducting simultaneously creates short circuit

(2) Cause - timing overlap during switching, insufficient dead-time, or noise

(3) Solution - hardware shoot-through protection prevents simultaneous conduction

(4) Implementation - driver monitors both outputs and forces dead-time

(5) Importance - shoot-through can destroy MOSFETs in microseconds, causes EMI, reduces efficiency. Linco drivers include hardware shoot-through protection independent of external control. This is essential for reliable motor drive operation. The protection adds inherent dead-time between high and low side switching.

Always use drivers with shoot-through protection. Essential for reliable half-bridge operation.

Bootstrap operation powers high-side gate drive: (1) Challenge - high-side MOSFET source floats with motor voltage, needs gate drive above source

(2) Solution - bootstrap capacitor charged from low-side supply when low-side is on

(3) Operation - capacitor provides floating supply for high-side driver

(4) Requirements - sufficient capacitor value, refresh time, voltage rating

(5) Limitations - duty cycle limited (typically <95%), initial charging needed. Bootstrap is cost-effective for motor drives where 100% duty cycle isn't required. For continuous high-side conduction, isolated supplies are needed. Linco drivers include integrated bootstrap diodes for simplified design.

Bootstrap suitable for most motor drives. Use isolated supply if >95% duty cycle needed.

Undervoltage Lockout (UVLO) protection in Linco drivers: (1) Purpose - prevents MOSFET operation with insufficient gate voltage

(2) Thresholds - typically 8-10V for turn-on, 7-9V for turn-off with hysteresis

(3) Behavior - driver outputs held low when VCC below threshold

(4) Importance - insufficient gate voltage causes high RDS(on), excessive heating, MOSFET damage

(5) Hysteresis - prevents oscillation near threshold. UVLO is essential for reliable operation during power-up, brown-out conditions, and transient events. Linco drivers have both VCC UVLO and bootstrap UVLO (for high-side). UVLO ensures MOSFETs are fully enhanced before operation begins.

UVLO essential for reliable operation. Ensure supply voltage stays above UVLO threshold.

Integrated vs standalone driver selection: (1) Integrated drivers (in MCU) - advantages: reduced BOM, smaller PCB, simpler design

disadvantages: limited drive current, MCU heat, less flexibility

(2) Standalone drivers - advantages: higher drive current, better thermal management, more protection features, design flexibility

disadvantages: additional component cost, PCB space

(3) Decision factors - motor power (<50W integrated OK, >100W standalone), MOSFET size (large Qg needs standalone), thermal constraints, cost sensitivity. Linco offers both options - LKS08 has integrated drivers for small motors, standalone drivers available for high-power applications. Many designs use integrated drivers for prototyping, standalone for production high-power.

Use integrated for small motors <50W. Use standalone for high power or large MOSFETs.