SiP32448, SiP32449

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Vishay Siliconix

S15-1920-Rev. C, 24-Aug-15

4

Document Number: 62959

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

BLOCK DIAGRAM

Fig. 3 - Functional Block Diagram

DETAILED DESCRIPTION

SiP32448 and SiP32449 are advanced slew rate controlled

high side load switches with an integrated N-channel power

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

switch is turned on at a controlled rate to avoid excessive

inrush 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.

A special reverse blocking circuitry prevents current flowing

pin can tolerate -2 V voltage without drawing excessive

current.

APPLICATION INFORMATION

Input Capacitor

In general, under steady state conditions the SiP32448 and

SiP32449 do not require an input capacitor. Nevertheless,

an input bypass capacitor is recommended in order to

reduce the input voltage drop caused by transient inrush

currents. Commonly, a 2.2 μF ceramic capacitor is sufficient

pins. A higher value input capacitor can help to further

reduce

the

voltage

drop.

Ceramic

capacitors

are

recommended for their low ESR characteristic.

Output Capacitor

While these devices work without an output capacitor, a

recommended in order to handle potential load transient

conditions. In the event that the switch is turning of while

running high current, circuit stray inductances might force

the output to some negative voltage in order to mitigate this

phenomenon a proper output capacitor is required.

Enable

The device is logic high active. Enable pin voltage can

rating range. The EN pin is compatible with both TTL and

CMOS logic voltage levels. The part features a constant

control logic threshold over the operation voltage range.



When enable pin is left open, a built-in voltage divider sets

exceeds the UVLO trip point.

Reverse Voltage Protection

The SiP32448 and SiP32449 contain a reverse blocking

circuitry to protect the current from going to the input from

the output when the switch is off. Reverse blocking works

for input voltage as low as 0 V.



In case the EN pin is left open, the reverse blocking circuitry

will prevents current flow from output pin to input pin if the

output voltage is higher by at least 1 V than the input

voltage.

THERMAL CONSIDERATIONS

The maximum allowed DC Current depends on the thermal

condition in which the device operates. In order to calculate

max allowed DC current, first the max power dissipation

should be considered.

The SiP32448 and SiP32449 are packaged in a TDFN4

1.2 mm x 1.6 mm package which has a thermal resistance of



J-A

Note

a. Device mounted with all leads and power pad soldered or

welded to PC board, see PCB layout. For any other layout

configuration the actual junction to ambient thermal impedance

should be considered

The following formula shows the maximum allowed power

when the maximum junction temperature is limited to



For example at ambient temperature of 70 °C, the maximum

power dissipation will be limited to about 324 mW.

Control

Logic

Charge

Pump

Turn-on

Slew Rate

Control

Output

Discharge

Negative

Voltage

Detect / Clamp

GND

EN

V

IN

SiP32448, SiP32449

SiP32449 only

=

A

170

T