SiP4282

Vishay Siliconix

Document Number: 73851

S-70069–Rev. C, 22-Jan-07

www.vishay.com

7

New Product

BLOCK DIAGRAM

DETAILED DESCRIPTION

The SiP4282 is a P-Channel MOSFET power switches

designed for high-side slew rate controlled load-switching

applications. Once turned on, the slew-rate control circuitry

is activated and current is ramped in a linear fashion until it

reaches the level required for the output load condition. This

is accomplished by first elevating the gate voltage of the

MOSFET up to its threshold voltage and then by linearly

increasing the gate voltage until the MOSFET becomes fully

enhanced. At this point, the gate voltage is then quickly

MOSFET switch and minimize any associated power losses.

The SiP4282-1 version has a modest 1 ms turn on slew rate

feature, which significantly reduces in-rush current at turned

on time and permits the load switch to be implemented with

a small input capacitor, or no input capacitor at all, saving

cost and space. In addition to a 100 µs minimized slew rate,

the SIP4282-3 features a shutdown output discharge circuit

which is activated at shutdown (when the part is disabled

through the ON/OFF pin) and discharges the output pin

through a small internal resistor hence, turning off the load.

In instances where the input voltage falls below 1.4 V (typi-

cally) the under voltage lock-out circuitry protects the MOS-

FET switch from entering the saturation region or operation

by shutting down the chip.

APPLICATION INFORMATION

Input Capacitor

While a bypass capacitor on the input is not required, a 1 µF

applications. The Bypass capacitor should be placed as

physically close as possible to the SiP4282 to be effective in

minimizing transients on the input. Ceramic capacitors are

recommended over tantalum because of their ability to with-

stand 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 SiP4282 turn on

slew rate time. There are no ESR or capacitor type require-

ment.

Enable

The ON/OFF pin is compatible with both TTL and CMOS

logic voltage levels.

Level

Shift

Under

Voltage

Lockout

Turn-On

Slew Rate

Control

SiP4282-3 version only

GND

ON/OFF

OUT

SiP4282 Functional Block Diagram