I/O Input

Ethernet

8 Port

IO-Link

Master

Remote I/O

Link

Control

ADC

Microcontroller

24 V

INA253

Power

Management

25

INA253

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SLOS954A – JULY 2018 – REVISED DECEMBER 2018

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9.2.3 Current Sensing for Remote I/Os in PLC

In industrial remote IOs, there is often one power supply for several ports, as shown in Figure 45. For example,

an IO-Link master has one power supply of 24 V 5 A, but eight IO-Link ports, where each port can deliver up to 1

A. The IO-Link master must measure the total current to make sure in order to not overload the power supply. To

prevent from overloading the system, each port is only turned on if sufficient headroom in the total system

current is available. Figure 45 shows the block diagram of such a system. This is example is implemented on TI

reference design TIDA-010016. The INA253 is an excellent choice for this design because this device is simple

to use, and delivers high accuracy over a wide temperature range. The integrated 2-mΩ shunt has a low voltage

drop .and therefore low power dissipation.

Figure 45. Current Sensing in Remote I/O

9.2.3.1 Design Requirements

Table 4. Design Parameters

DESIGN PARAMETER

EXAMPLE VALUE

Common-mode voltage

24 V

Maximum current

9 A

ADC input voltage

1.8 V

Supply voltage

3.3 V

In this design, the current flow is unidirectional; therfore, the REF inputs must be tied to GND. Because of the

given ADC input range and current, the 200-mV/A version is chosen.