SIP4282A Vishay, SIP4282A Datasheet - Page 7

• Manufacturer Part Number: SIP4282A
• Description: Vishay Power Ics 1.2 A Slew Rate Controlled Load Switch In Ppak Sc75
• Manufacturer: Vishay

BLOCK DIAGRAM
DETAILED DESCRIPTION
The SiP4282A 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
increased to the full input voltage to reduce R
MOSFET switch and minimize any associated power losses.
The SiP4282A-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 SIP4282A-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
(typically) the under voltage lock-out circuitry protects the
MOSFET switch from entering the saturation region or
operation by shutting down the chip.
Document Number: 74480
S-71378–Rev. B, 23-Jul-07
ON/OFF
V
IN
Voltage
Lockout
Under
DS(ON)
SiP4282A Functional Block Diagram
of the
New Product
Level
Shift
GND
APPLICATION INFORMATION
Input Capacitor
While a bypass capacitor on the input is not required, a 1 µF
or larger capacitor for C
applications. The Bypass capacitor should be placed as
physically close as possible to the SiP4282A 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 µF capacitor or larger across V
recommended to insure proper slew operation. C
increased without limit to accommodate any load transient
condition with only minimal affect on the SiP4282A 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.
Slew Rate
Turn-On
Control
SiP4282A-3 version only
IN
is recommended in almost all
OUT
Vishay Siliconix
SiP4282A
OUT
www.vishay.com
and GND is
OUT
may be
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