SIP32454DB-T2-GE1 Vishay/Siliconix, SIP32454DB-T2-GE1 Datasheet - Page 9

• Manufacturer Part Number: SIP32454DB-T2-GE1
• Description: Power Switch ICs - Power Distribution Slew Rate Controled Loadswitch
• Manufacturer: Vishay/Siliconix

Specifications of SIP32454DB-T2-GE1

• Rohs: yes

DETAILED DESCRIPTION
SiP32454 and SiP32455 are n-channel power MOSFET
designed as high side load switch. Once enable the device
charge pumps the gate of the power MOSFET to a constant
gate to source voltage for fast turn on time. The mostly
constant gate to source voltage keeps the on resistance low
through out the input voltage range. SiP32454 and SiP32455
are designed with slow slew rate to minimize the inrush
current during turn on. Because the body of the output
n-channel is always connected to GND, it prevents the
current from going back to the input in case the output
voltage is higher than the output. The SiP32454 especially
incorporates an active output pulldown resistor to discharge
output capacitance when the device is off.
APPLICATION INFORMATION
Input Capacitor
While a bypass capacitor on the input is not required,
a 4.7 µF or larger capacitor for C
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
A 0.1 µF capacitor across V
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 the C
the higher the inrush current. There are no ESR or capacitor
type requirement.
Enable
The EN pin is compatible with CMOS logic voltage levels. It
requires at least 0.1 V or below to fully shut down the device
and 1.5 V or above to fully turn on the device.
Protection Against Reverse Voltage Condition
Both the SiP32454 and SiP32455 can block the output
current from going to the input in case where the output
voltage is higher than the input voltage when the main switch
is off.
Thermal Considerations
These devices are 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,
T
θ
may be formulaically expressed as:
Document Number: 62531
S12-0967-Rev. A, 07-May-12
THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT
J-A
J(max.)
= 280 °C/W, and the ambient temperature, T
= 125 °C, the junction-to-ambient thermal resistance,
OUT
For technical questions, contact:
IN
and GND is recommended
is recommended in almost
This document is subject to change without notice.
A
, which
OUT
[e-mail]
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 two
things: the package power dissipation and the R
ambient temperature.
As an example let us calculate the worst case maximum load
current at T
35 mΩ. The R
data using the following formula:
R
Where T
we have
R
= 42.2 mΩ
The maximum current limit is then determined by
which in this case is 2.1 A. Under the stated input voltage
condition, if the 2.1 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.
DS(ON)
DS(ON)
(at 70 °C) = R
(at 70 °C) = 35 mΩ x (1 + 0.0041 x (70 °C - 25 °C))
C
P
(max.)
is 4100 ppm/°C. Continuing with the calculation
A
= 70 °C. The worst case R
DS(ON
I
LOAD
=
) at 70 °C can be extrapolated from this
T
SiP32454, SiP32455
DS(ON)
(max.)
J
(max.)
θ
J
-
<
A
(at 25 °C) x (1 + T
-
T
R
A
P
Vishay Siliconix
DS
(max.)
www.vishay.com/doc?91000
(
=
ON
)
125
DS(ON)
280
www.vishay.com
-
T
DS(ON)
C
A
at 25 °C is
x ΔT)
at the
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