V+

OUT

GND

IN-

IN+

C

BYPASS

0.01 F

m

to

0.1 F

m

+2.7V to +26V

REF

Reference

Voltage

Supply

Load

R

SHUNT

Output

R

1

R

3

R

2

R

4

INA199A1, INA199B1

INA199A2, INA199B2

INA199A3, INA199B3

www.ti.com

SBOS469D – MAY 2009 – REVISED NOVEMBER 2012

APPLICATION INFORMATION

BASIC CONNECTIONS

Figure 20 shows the basic connections for the INA199. The input pins, IN+ and IN–, should be connected as

closely as possible to the shunt resistor to minimize any resistance in series with the shunt resistance.

Figure 20. Typical Application

Power-supply bypass capacitors are required for stability. Applications with noisy or high-impedance power

supplies may require additional decoupling capacitors to reject power-supply noise. Connect bypass capacitors

close to the device pins.

On the RSW package, two pins are provided for each input. These pins should be tied together (that is, tie IN+ to

IN+ and tie IN– to IN–).

POWER SUPPLY

The input circuitry of the INA199 can accurately measure beyond its power-supply voltage, V+. For example, the

V+ power supply can be 5V, whereas the load power-supply voltage can be as high as +26V. However, the

output voltage range of the OUT terminal is limited by the voltages on the power-supply pin. Note also that the

INA199 can withstand the full –0.3V to +26V range in the input pins, regardless of whether the device has power

applied or not.

The zero-drift offset performance of the INA199 offers several benefits. Most often, the primary advantage of the

low offset characteristic enables lower full-scale drops across the shunt. For example, non-zero-drift current

shunt monitors typically require a full-scale range of 100mV.

The INA199 series of current-shunt monitors give equivalent accuracy at a full-scale range on the order of 10mV.

This accuracy reduces shunt dissipation by an order of magnitude with many additional benefits.

Alternatively, there are applications that must measure current over a wide dynamic range that can take

advantage of the low offset on the low end of the measurement. Most often, these applications can use the lower

gain of 50 or 100 to accommodate larger shunt drops on the upper end of the scale. For instance, an INA199A1

operating on a 3.3V supply could easily handle a full-scale shunt drop of 60mV, with only 150

μV of offset.

Copyright © 2009–2012, Texas Instruments Incorporated

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