RT9728

8

DS9728-05

October 2014

www.richtek.com

©

Copyright

2014 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

Application Information

The RT9728 is a single P-MOSFET high side power switch

with active high enable input, optimized for self powered

and bus powered Universal Serial Bus (USB) applications.

requirements and a flag output is available to indicate fault

conditions to the local USB controller.

Current Limiting and Short Circuit Protection

When a heavy load or short circuit situation occurs while

the switch is enabled, large transient current may flow

through the device. The RT9728 includes a current limit

circuitry to prevent these large currents from damaging

RT9728 provides an adjustable current limit threshold

between 120mA and 1.3A (typ.) via an external resistor,

Ω and 232kΩ. However, if the ILIM

75mA (typ.). Once the current limit threshold is exceeded,

Ω

0

200

400

600

800

1000

1200

1400

1600

20

50

80

110

140

170

200

230

Actual Limits (Include R Tolerance)

Desired Nominal

Current Limit (mA)

Ideal Resistor

(k

)

Closet 1%

Resistor (k

)

IOS Min (mA)

IOS Nom (mA)

IOS Max (mA)

75

Short Ilim to VIN

50.0

75.0

100.0

120

226.1

226.0

101.3

120.0

142.1

200

134.0

133.0

173.7

201.5

233.9

300

88.5

88.7

262.1

299.4

342.3

400

65.9

66.5

351.1

396.7

448.7

500

52.5

52.3

443.9

501.6

562.4

600

43.5

43.2

535.1

604.6

674.1

700

37.2

37.4

616.0

696.0

776.0

800

32.4

32.4

708.7

800.8

892.9

900

28.7

28.7

797.8

901.5

1005.2

1000

25.8

26.1

875.4

989.1

1102.8

1100

23.4

23.2

982.1

1109.7

1237.3

1200

21.4

21.5

1057.9

1195.4

1332.9

1300

19.7

19.6

1158.0

1308.5

1459.0

thermal shutdown occurs or the fault is removed. The table1