How is an op amp used for high side current sensing?

How is an op amp used for high side current sensing?

Using An Op Amp for High-Side Current Sensing Tim Claycomb, Marc Liu High-side current sensing is used in a wide range of applications such as battery chargers or overcurrent protection. Figure 1 displays a typical high-side current sensing schematic. The shunt resistor, Rshunt, is placed between the bus voltage and the system load creates

How is the common mode voltage of an op amp determined?

Current Sensing The common mode voltage of the operational amplifier (op amp) must be considered when designing a high- side current sensing circuit. The common mode voltage is set by the bus voltage and the resistor divider formed by resistor R1 and R2, in Figure 1, and is calculated using Equation 1.

Which is the best low power op amp?

TSZ12 series: ultra… ST’s low-power op amp portfolio includes several series covering different voltage ranges, as well as many possible combinations of power consumption and gain bandwidth, providing the optimal performance for the appropriate power budget.

Why is it important to measure op amps?

They are often used in high precision analog circuits, so it is important to measure their performance accurately.

Is the op amp connected to the ground?

A simple High-Side Current Sense A simple Low-Side Current Sense No, the circuit will not function properly unless the psu ground and 12V ground are connected together. If they are not, the voltages on the inputs of the op amp are indeterminate.

How does a low side current sensing circuit work?

As shown in Figure 1, low-side current sensing connects the sensing resistor between the load and ground. Normally, the sensed voltage signal (VSEN =ISEN × RSEN) is so small that it needs to be amplified by subsequent op amp circuits (e.g., non- inverting amplifier) to get the measurable output voltage (VOUT).

How are op amps used in an IC?

Same as like LM358, many op-amp ICs have two op-amps in a single package. If the input voltage is too low, the second unused op-amp can be used to amplify the input voltage as required. For the improvement of the thermal and efficiency issues, low on-resistance MOSFETs can be used along with proper heat sink.

How does an op amp work in a circuit?

Basically I pass the output through a 1Ohm power resistor and feed the voltage on both sides of the sense resistor into an op amp in differential configuration. After that the output of op amp 1 goes into the non-inverting input of a second op amp that is configured as a comparator against a reference voltage adjusted by a pot .

What kind of amplifier is used for current sensing?

This article introduces the four differential amplifiers that typically are used in direct current sensing solutions: operational amplifiers (op amps), difference amplifiers (DA), instrumentation amplifiers (IA), and current shunt monitors (CSM). The use of an op amp for current sensing is limited by input common-mode voltage.

Can a difference amplifier be used for low side sensing?

Difference amplifiers, however, can be used for high-side current sensing in the presence of high common-mode voltages at the expense of drawing current from the system bus supply. They can also be used for low-side sensing and negate the effects of parasitic resistances to ground.

Why is the use of an op amp limited?

The use of an op amp for current sensing is limited by input common-mode voltage. Due to the design of the input stage, input common-mode voltage of such a device is limited by the supply voltage (Voa).

How does an over-top current sense circuit work?

Over-The-Top Current Sense. This circuit takes advantage of the microampere supply current and rail-to-rail input of the LT1494. The circuit is simple because the supply draw is essentially equal to the load current developed through R A. This supply current is simply passed through R B to form an output voltage that is appropriately amplified.

How does high side current sensing circuit work?

High-Side Current Sensing. As shown in Figure 2, high-side current sensing connects the sensing resistor between the power supply and load. The sensed voltage signal is amplified by subsequent op amp circuits to get the measurable VOUT.

What is the DC range of a current sense amplifier?

This specification defines the DC voltage range at the input of an amplifier with respect to ground. Current sense amplifiers are typically designed to support common-mode voltages well beyond the chip supply voltage.