We use the ADI LTC4210 as an example to demonstrate a typical single-channel 5V hot-swappable connector.
The LTC4210 utilizes a charge pump to drive the N-channel MOSFET (Q1):
Driving Logic:The internal charge pump within the controller boosts VCC (5V) to a high voltage (>10V) at the GATE pin. This fully turns on the Si4410DY (low on-resistance MOSFET).
Control Method:The GATE pin implements gate frequency compensation (corresponding to the “Gate Frequency Compensation” principle) via an RC network (100Ω in series + 100Ω in parallel + 0.01μF to ground):
- 100Ω Series Resistor: Suppresses high-frequency parasitic oscillations (>1MHz) and limits gate sink current.
- 0.01μF Shunt Capacitor: Increases total gate capacitance to control the rate of voltage rise (core of soft-start).
- 100Ω Pull-down Resistor: Quickly pulls down the GATE voltage to shut off the MOSFET in case of a fault.
Waveform Verification:During power-up, VOUT rises slowly from 0V, which is a direct result of the slowly rising GATE voltage, corresponding to the soft-start voltage ramp.
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