9 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification, and TI

does not warrant its accuracy or completeness. TI’s customers are responsible for determining

suitability of components for their purposes. Customers should validate and test their design

implementation to confirm system functionality.

9.1 Application Information

The TPS2559 current limited power switch uses N-channel MOSFETs in applications requiring up to 5.5 A of

continuous load current. The device enters constant-current mode when the load exceeds the current limit

threshold.

The TPS2559 power switch is used to protect the up-stream power supply when the output is overloaded.

9.2 Typical Application

IN

GND

FAULT

Control

Signal

5 V

0.1PF

150µF

Fault

Signal

Power

Pad

VOUT

EN

OUT

10kŸ

ILIM

RILIM

*

TPS2559

5

2/ 3/4

10

6

7/ 8/9

1

Figure 9-1. Typical TPS2559 Power Switch

Use the IOS in the Electrical Characteristics table or IOS in Equation 1 to select the RILIM.

9.2.1 Design Requirements

Table 9-1 lists the input parameters for this design example.

Table 9-1. Design Requirements

DESIGN PARAMETERS

EXAMPLE VALUE

Input operation voltage

5 V

Rating current

3 A or 4.5 A

Minimum current limit

3 A

Maximum current limit

5 A

When choosing a power switch, there are several general steps:

1. Determine what is the power rail, 3.3 V or 5 V, and then choose the operation range of the power switch that

can cover the power rail voltage range.

2. Determine what is the normal operation current. For example, the maximum allowable current drawn by

portable equipment for a USB 2.0 port is 500 mA, so the normal operation current is 500 mA and the

minimum current limit of power switch must exceed 500 mA to avoid false trigger during normal operation.

3. Determine what is the maximum allowable current provided by up-stream power, and then decide the

maximum current limit of the power switch that must lower it to ensure the power switch can protect the up-

stream power when an overload is encountered at the output of the power switch.

TPS2559

SLVSCL5A – JUNE 2014 – REVISED NOVEMBER 2020

www.ti.com

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