TSV792IST datasheet(25/36 Pages) STMICROELECTRONICS

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Typical applications

6.1

Low-side current sensing

Power management mechanisms are found in most electronic systems. Current sensing is useful for protecting

applications. The low-side current sensing method consists of placing a sense resistor between the load and the

circuit ground. The resulting voltage drop is amplified using the TSV79x (see Figure 48).

Figure 49. Low-side current sensing schematic

Vout can be expressed as follows:

VOut=Rsℎunt.I1− Rg2

Rg2+Rf2 . 1+Rf1Rg1 +Ip. Rg2.Rf2

Rg2+Rf2. 1+Rf1Rg1 −In.Rf1

−Vio. 1+Rf1Rg1

(10)

Assuming that Rf2 = Rf1 = Rf and Rg2 = Rg1 = Rg, Equation 10 can be simplified as follows:

VOut=Rsℎunt.I.RfRg−Vio. 1+RfRg +Rf.Iio

(11)

The main advantage of using the TSV79x for a low-side current sensing relies on its low Vio, compared to general

purpose operational amplifiers. For the same current and targeted accuracy, the shunt resistor can be chosen

with a lower value, resulting in lower power dissipation, lower drop in the ground path, and lower cost. Particular

attention must be paid to the matching and precision of Rg1, Rg2, Rf1, and Rf2, to maximize the accuracy of the

measurement.

6.2

Photodiode transimpedance amplification

The TSV79x, with high bandwidth and slew rate, is well suited for photodiode signal conditioning in a

transimpedance amplifier circuit. This application is useful in high performance UV sensors, smoke detectors

or particle sensors.

TSV791, TSV792

Typical applications

DS13480 - Rev 1

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