8.2 Typical Applications

8.2.1 High-Side Current Sensing

+

–

+ 24 V –

+

24 V

–

R1

R2

R3

R4

OPA2186

Load Current

R1 = R3, R2 = R4

Figure 8-2. High-Side Current Monitor

8.2.1.1 Design Requirements

A common systems requirement is to monitor the current being delivered to a load. Monitoring makes sure that

normal current levels are being maintained, and also provides an alert if an overcurrent condition occurs.

Fortunately, a relatively simple current monitor solution can be achieved using a precision rail-to-rail input/output

200 mV beyond each power supply rail allowing for operation at the supply rail.

The OPA2186 is configured as a difference amplifier with a predetermined gain. The difference amplifier inputs

are connected across a sense resistor through which the load current flows. The sense resistor may be

connected to the high side or low side of the circuit through which the load current flows. Commonly, high-side

current sensing is applied. Figure 8-2 shows an applicable OPA2186 configuration. Low-side current sensing

may be applied as well if the sense resistor can be placed between the load and ground.

Use the following parameters for this design example:

• Single supply: 24 V

• Linear output voltage range: 0.3 V to 3.3 V

The design details and equations below can be used to reconfigure this design for different output voltage

ranges and current loads.

OPA2186

SBOS968 – JUNE 2022

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