S39421 View Datasheet(PDF) - Summit Microelectronics

Part Name

Description

Manufacturer

S39421

Hot Swap Voltage Controller

Summit Microelectronics 

S39421

Card Power-Down

The S39421 provides a turn-on slew-rate of 250V/s and a

fast turn-off performed by internally shorting the VGATE3

and VGATE5 outputs to ground. If the card circuitry or

host power supply cannot accept a fast shutdown then a

CR time constant may be added as shown below. The

resistors in series with the 47nF(X7R) capacitors increase

the discharge time of the MOSFET gates. The values

shown provide a shutdown slew of ~5V/ms. Decreasing

the resistor values increases the shutdown slew-rate, and

vice-versa. The capacitor values may also be increased

but this will decrease the 250V/s turn-on slew-rate.

VGATE3

VGATE5

56kΩ

56kΩ

47nF

to 3V MOSFET

to 5V MOSFET

47nF

GND

2024 ILL25.0

FIGURE 20. POWER-DOWN RAMP RATE CONTROL

2024 9.0 8/8/00

17

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