9.2.1 Design Requirements

Table 9-1. Recommended External Components

COMPONENT

TYPICAL VALUE

PURPOSE

RPROT

5-10 kΩ

Protect microcontroller and device I/O pins

RST

4.7 kΩ

Open-drain pull-up resistor

RILIMx

13.3 kΩ to 110 kΩ

Discrete value outlined in Table 8-1

CVin1

100 nF to System GND

Stabilize the input supply and filter out low frequency noise

CVin2

4.7 nF to IC GND

Filtering of voltage transients (for example, ESD, IEC 61000-4-5) and improved

emissions

CVDD

2.2 uF to Module GND

Stabilize the input supply and limit supply excursions.

COUT

22 nF

Filtering of voltage transients (for example, ESD, RF transients)

ZTVS

36-V TVS

Clamp surge voltages at the supply input

DGND

Diode with < 0.7-V forward

voltage drop

Optional for reverse polarity protection - if needed

RGND

4.7 kΩ

Stabilize IC GND in the event of negative output swings when GND network is

used

9.2.2 Detailed Design Procedure

In an example application with maximum load current of 500 mA, the current limit must be set to an acceptable

level. With the current limit variation and tolerance allowed for this specific application, the current limit setting

of 1 A is chosen. Referring back to the Table 8-1, 44.2-kΩ resistor with 1% tolerance needs to be placed at the

ILIMCFG pin.

Depending on the tolerance on the maximum current for the application, the current limit resistor can be chosen

to leave the overhead needed before the current limit engages.

9.2.2.1 IEC 61000-4-5 Surge

The TPS274C65 is designed to survive against IEC 61000-4-5 surge using external TVS clamps. The device

is rated to 48 V ensuring that external TVS diodes can clamp below the rated maximum voltage of the

TPS274C65. Above 48 V, the device includes VDS clamps to help shunt current and ensure that the device

survives the transient pulses. Depending on the class of the output,TI recommends that the system has a

SMBJ36A or SMCJ36A between VS and module GND.

9.2.2.2 Loss of GND

The ground connection can be lost either on the device level or on the module level. If the ground connection is

lost, both the channel outputs are disabled irrespective of the EN input level. If the switch was already disabled

when the ground connection was lost, the outputs remain disabled even when the channels are enabled. The

steady state current from the output to the load that remains connected to the system ground is below the

level specified in the Specifications section of this document. When the ground is reconnected, normal operation

resumes.

9.2.2.3 Paralleling Channels

If an application requires lower power dissipation than is possible with a 65-mΩ switch. Since the retry timer

for each channel is not synchronized in TPS274C65CP, TI recommends to have the current limit for a single

channel set higher than the total current for the paralleled channel. For example, if two of the channel are

paralleled to drive 2A total current through the two channels, then the individual channel current limit needs to be

set higher than 2A.

If the current limit cannot be set higher, a manual toggle of ENx (enable signals for the channels being

paralleled) is needed after a thermal fault event happened.

TPS274C65CP

SLVSH35A – OCTOBER 2023 – REVISED FEBRUARY 2024

www.ti.com

26

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