SiP32401A, SiP32402A

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Vishay Siliconix

S15-1246-Rev. D, 01-Jun-15

9

Document Number: 63705

THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT

PCB LAYOUT

Fig. 27 - PCB Layout for TDFN4 1.2 mm x 1.6 mm (type: FR4, size: 1" x 1", thickness: 0.062", copper thickness: 2 oz.)

DETAILED DESCRIPTION

SiP32401A and SiP32402A are advanced slew rate

controlled high side load switch consisted of a n-channel

power switch. When the device is enable the gate of the

power switch is turned on at a controlled rate to avoid

excessive in-rush current. Once fully on the gate to source

voltage of the power switch is biased at a constant level. The

design gives a flat on resistance throughout the operating

voltages. When the device is off, the reverse blocking

circuitry prevents current from flowing back to input if output

is raised higher than input. The reverse blocking mechanism

also works in case of no input applied. The SiP32402A also

integrates an output discharge switch which allows fast

output discharge.

APPLICATION INFORMATION

Input Capacitor

The SiP32401A and SiP32402A do not require an input

capacitor. To limit the voltage drop on the input supply

caused by transient inrush currents, an input bypass

capacitor is recommended. A 2.2 μF ceramic capacitor

Higher values capacitor can help to further reduce the

voltage drop. Ceramic capacitors are recommended for

their ability to withstand input current surge from low

impedance sources such as batteries in portable devices.

Output Capacitor

While these devices works without an output capacitor,

recommended to accommodate load transient condition. It

GND when switching off. Output capacitor has minimal

affect on device’s turn on slew rate time. There is no

requirement on capacitor type and its ESR.

Enable

The EN pin is compatible with both TTL and CMOS logic

voltage levels.

Protection Against Reverse Voltage Condition

Both SiP32401A and SiP32402A contain 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. Reverse

blocking works for input voltage as low as 0 V.

Thermal Considerations

SiP32401A and SiP32402A 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 2.8 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 170 °C/W) the power pad of the device

should be connected to a heat sink on the printed circuit

board. Figure 23 shows a typical PCB layout. All copper

traces and vias for the IN and OUT pins should be sized

adequately to carry the maximum continuous current.

The maximum power dissipation in any application is

dependant

on

the

maximum

junction

temperature,

resistance for the TDFN4 1.2 mm x 1.6 mm package,

formulaically expressed as:

Top

Bottom

170

125

(max.)

(max.)

A

A

J

A

J

T

T

T

P

-

=

-

=

-

θ