SiP4280

Vishay Siliconix

www.vishay.com

8

Document Number: 73476

S–52468—Rev. B, 28-Nov-05

DETAILED DESCRIPTION

The SiP4280 is a P–channel MOSFET power switches

designed for high–side slew rate controlled load–switching

applications. During turn on, the current ramps linearly until it

reaches the level required for the output load condition. This is

achieved by first applying the threshold voltage on the gate of

the MOSFET. Once at this level, the current begins to slew and

the gate voltage is then linearly increased until the MOSFET

becomes fully enhanced. Once fully enhanced, the gate is

minimized.

The SiP4280–1 version has a moderate 1ms turn on slew rate

feature, which reduces in–rush current when the MOSFET is

turned on. This function allows the load switch to be

implemented with a small input capacitor, or no input capacitor

at all. The SIP4280–3 has in addition to the 100

ms minimized

slew rate limited turn on function, a shutdown output discharge

circuit to rapidly turn off a load when the load switch is disabled

through the ON/OFF pin.

Both versions of the SiP4280 operate with input voltages

ranging from 1.8 V to 5.5 V. Also, both versions of this device

have extremely low operating current, making them ideal for

battery–powered applications. In cases where the input

voltage drops below 1.8 V, the under voltage lockout function

will prevent the P–channel MOSFET device from entering into

the saturation region of operation by automatically shutting

down SiP4280. The ON/OFF control pin is TTL compatible and

will also function with 2.5 volt to 5 volt CMOS logic systems.

APPLICATION INFORMATION

Input Capacitor

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

mF

plications. The Bypass capacitor should be placed as phy–

sically close as possible to the SiP4280 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

A 0.1

increased without limit to accommodate any load transient

condition with only minimal affect on the SiP4280 turn on slew

rate time. There are no ESR or capacitor type requirement.

Enable

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

voltage levels.

Reverse Voltage Conditions and Protection

The P–channel MOSFET pass transistor has an intrinsic diode

that is reversed biased when the input voltage is greater than

diode will become forward biased and allow excessive current

IC device. Therefore extreme care should be taken to prevent

parallel with the internal intrinsic diode is recommended to

protect the SiP4280.

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 reliability data, see