S39421 View Datasheet(PDF) - Summit Microelectronics
Part Name
Description
MFG CO.
'S39421' PDF : 28 Pages View PDF
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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