SiP32472

www.vishay.com

Vishay Siliconix

S13-1349-Rev. B, 03-Jun-13

9

Document Number: 62512

THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT

DETAILED DESCRIPTION

SiP32472 has a P-channel power MOSFET designed as a

high side load switch. It incorporates a negative charge

pump at the gate to keep the gate to source voltage high

when turned on therefore keep the on resistance low at

lower input voltage range. SiP32472 is designed with slow

slew rate to minimize the inrush current during turn on. This

device has a reverse blocking circuit to prevent the current

from going back to the input in case the output voltage is

higher than the input voltage. The SiP32472 has an output

pulldown resistor to discharge the output capacitance when

the device is off.

APPLICATION INFORMATION

Input Capacitor

While a bypass capacitor on the input is not required, a

all applications. The bypass capacitor should be placed as

physically close as possible to the input pin to be effective

in minimizing transients on the input. Ceramic capacitors are

recommended over tantalum because of their ability to

withstand input current surges from low impedance sources

such as batteries in portable devices.

Output Capacitor

to insure proper slew operation. There is inrush current

through the output MOSFET and the magnitude of the

inrush current depends on the output capacitor, the bigger

capacitor type requirement.

Enable

The EN pin is compatible with CMOS logic voltage levels. It

requires at least 0.4 V or below to fully shut down the device

and 1 V or above to fully turn on the device. There is a

2.8 M

 resistor connected between EN pin and GND pin.

Protection Against Reverse Voltage Condition

This device contains a reverse blocking circuit to keep the

output current from flowing back to the input in case the

output voltage is higher than the input voltage.

Thermal Considerations

This device is designed to maintain a constant output load

current. Due to physical limitations of the layout and

assembly of the device the maximum switch current is 1.2 A

as stated in the Absolute Maximum Ratings table. However,

another limiting characteristic for the safe operating load

current is the thermal power dissipation of the package. To

obtain the highest power dissipation (and a thermal

resistance of 280 °C/W) the device should be connected to

a heat sink on the printed circuit board.

The maximum power dissipation in any application

is dependant on the maximum junction temperature,

resistance,



It then follows that, assuming an ambient temperature of

70 °C, the maximum power dissipation will be limited to

about 196 mW.

So long as the load current is below the 1.2 A limit, the

maximum continuous switch current becomes a function

at the ambient temperature.

As an example let us calculate the worst case maximum

is 65 m

 at V

extrapolated from this data using the following formula:

we have

= 73.2 m



The maximum current limit is then determined by

which in this case is 1.6 A. Under the stated input voltage

condition, if the 1.6 A current limit is exceeded the internal

die temperature will rise and eventually, possibly damage

the device.

To avoid possible permanent damage to the device and

keep a reasonable design margin, it is recommended to

operate the device maximum up to 1.2 A only as listed in the

Absolute Maximum Ratings table.

280

125

(max.)

(max.)

A

A

J

A

J

T

T

T

P

-

=

-

=

-

θ

)

(

(max.)

(max.)

ON

DS

LOAD

R

P

I

<