SiP32411

Vishay Siliconix

Document Number: 66710

S11-1694-Rev. E, 22-Aug-11

www.vishay.com

9

This document is subject to change without notice.

DETAILED DESCRIPTION

SiP32411 is an n-channel power MOSFET designed as high

side load switch with slew rate control to prevent in-rush

current. Once enable the device charge pumps the gate of

the power MOSFET to 5 V gate to source voltage while

controlling the slew rate of the turn on time. The mostly

constant gate to source voltage keeps the on resistance low

through out the input voltage range. When disable, the

output discharge circuit turns on to help pull the output

voltage to ground more quickly. Also in disable mode, the

reverse blocking circuit is activated to prevent current from

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

than the input voltage. Input voltage is needed for the reverse

APPLICATION INFORMATION

Input Capacitor

While a bypass capacitor on the input is not required,

all applications. The bypass capacitor should be placed as

physically close as possible to the SiP32411 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

increased without limit to accommodate any load transient

condition with only minimal affect on the SiP32411 turn on

slew rate time. There are no ESR or capacitor type

requirement.

Enable

The EN pin is compatible with both TTL and CMOS logic

voltage levels.

Protection Against Reverse Voltage Condition

The SiP32411 contains a reverse blocking circuitry to protect

the current from going to the input from the output in case

where the output voltage is higher than the input voltage

when the main switch is off. A supply voltage as low as the

minimum required input voltage is necessary for this circuitry

to work properly.

Thermal Considerations

The SiP32411 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 1.8 A

for SC70-6 package and 2.4 A for TDFN4 package, 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

240 °C/W for SC70-6 and 170 °C/W for TDFN4) the power

pad of 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,

for the TDFN4 1.2 mm x 1.6 mm package,



expressed as:

It then follows that, assuming an ambient temperature of

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

324 mW.

So long as the load current is below the 2.4 A limit, the

maximum continuous switch current becomes a function two

ambient temperature.

As an example let us calculate the worst case maximum load

occurs at an input voltage of 1.2 V and is equal to 75 m

. The

the following formula:

we have

= 86.5 m



The maximum current limit is then determined by

which in case is 1.94 A. Under the stated input voltage

condition, if the 1.94 A current limit is exceeded the internal

die temperature will rise and eventually, possibly damage the

device.

Vishay Siliconix maintains worldwide manufacturing capability. Products may be manufactured at one of several qualified locations. Reliability data for Silicon

Technology and Package Reliability represent a composite of all qualified locations. For related documents such as package/tape drawings, part marking, and

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