TSC2012IDT datasheet(23/50 Pages) STMICROELECTRONICS

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Application information

5.1

Overview

The TSC2011 is especially designed to accurately measure the current by amplifying the voltage across a shunt

resistor connected to its input. This voltage drop Vsense is then amplified by an instrumentation amplifier providing

a max. input offset voltage of 500 µV (25°C) for an input common voltage of 12 V.

The TSC2011 is a fixed gain current sensing amplifier of 60 V/V. Thanks to a thin film resistor, the TSC2011 offers

an extremely precise gain and a very high CMRR performance even in a high frequency range. Moreover, by

fixing the output common mode voltage, the TSC2011 can be either used as unidirectional or bidirectional current

sensing amplifier.

The TSC2011 provides an extended input common range from - 20 V below the negative supply voltage, and up

to 70 V allowing either low-side or high-side current sensing, while the TSC2011 device can operate from 2.7 to

5.5 V.

The parameters are very stable in the full Vcc range and characterization curves show the TSC2011

characteristics at 2.7 V and 5.0 V. Moreover, the main specifications are guaranteed in an extended temperature

range from -40 to 125 °C.

5.2

Theory of operation

The main feature of the TSC2011 is the ability to work with an input common mode voltage largely beyond the

power supply Vcc range (2.7 V to 5.5 V). It is ideal, for example for automotive applications where a reverse

battery can be supported by the TSC2011 without any damage. It also works with 48 V battery applications as the

TSC2011 can support and measure the current on line at voltage up to 70 V. No additional protective components

are needed in that range.

•

Vcc < Vicm < 70 V

In this case, the power supply of the TSC2011 is issued by the input and not only by the Vcc power supply. More

precisely, a current is drawn by the common mode rail as depicted in the Figure 54. Power supply when Vicm >

Vcc to power it.

Figure 54. Power supply when Vicm > Vcc

In Figure 55. Input bias current vs. common mode voltage Vcc = 5 V, the current used to power the TSC2011

increases together with the Vicm voltage. The slope represents the internal common mode resistances. The most

part of the current is drawn by the pin In+ as we can see on the iibp curve of Figure 9. Input bias current vs.

temperature with VCC = 5 V the current is around 450 µA. Some of it being Vicm / (R4+R1) and some supplies the

input stage of the circuit, roughly 250 µA. On the In- pin 250 µA is drawn only.

TSC2010, TSC2011, TSC2012

Application information

DS13057 - Rev 7

page 23/50

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