INA206 datasheet(11/23 Pages) TI

11 / 23 page

INA206

INA207

INA208

SBOS360 − JULY 2006

www.ti.com

APPLICATIONS INFORMATION

BASIC CONNECTION

Figure 2 shows the basic connection of the INA206,

INA207, and INA208. The input pins, VIN+ and VIN−, should

be connected as closely as possible to the shunt resistor

to minimize any resistance in series with the shunt

resistance.

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.

POWER SUPPLY

The input circuitry of the INA206, INA207, and INA208 can

accurately measure beyond the power-supply voltage, V+.

For example, the V+ power supply can be 5V, whereas the

load power-supply voltage is up to +80V. The output

voltage range of the OUT terminal, however, is limited by

the voltages on the power-supply pin.

ACCURACY VARIATIONS AS A RESULT OF

VSENSE AND COMMON-MODE VOLTAGE

The accuracy of the INA206, INA207, and INA208 current

shunt monitors is a function of two main variables: VSENSE

(VIN+ − VIN−) and common-mode voltage, VCM, relative to

the supply voltage, VS. VCM is expressed as (VIN+ + VIN−)/2;

however, in practice, VCM is seen as the voltage at VIN+

because the voltage drop across VSENSE is usually small.

This section addresses the accuracy of these specific

operating regions:

Normal Case 1: VSENSE

≥ 20mV, VCM ≥ VS

Normal Case 2: VSENSE

≥ 20mV, VCM < VS

Low VSENSE Case 1: VSENSE < 20mV, −16V

≤ VCM < 0

Low VSENSE Case 2: VSENSE < 20mV, 0V

≤ VCM ≤ VS

Low VSENSE Case 3: VSENSE < 20mV, VS < VCM

≤ 80V

Normal Case 1: VSENSE ≥ 20mV, VCM ≥ VS

This region of operation provides the highest accuracy.

Here, the input offset voltage is characterized and

measured using a two-step method. First, the gain is

determined by Equation (1).

OUT1 * VOUT2

100mV

* 20mV

where:

VOUT1 = Output Voltage with VSENSE = 100mV

VOUT2 = Output Voltage with VSENSE = 20mV

Then the offset voltage is measured at VSENSE = 100mV

and referred to the input (RTI) of the current shunt monitor,

as shown in Equation (2).

OSRTI (Referred−To−Input) +

OUT1

* 100mV

In the Typical Characteristics, the Output Error vs

Common-Mode

Voltage

curve

shows

the

highest

accuracy for the this region of operation. In this plot,

VS = 12V; for VCM

≥ 12V, the output error is at its minimum.

This case is also used to create the VSENSE

≥ 20mV output

specifications in the Electrical Characteristics table.

INA206

x20

SHUNT

Ω

Load Supply

−18V to +80V

Load

5V Supply

Optional Delay

Capacitor

0.2

µF/s

BYPASS

0.01

µF

OUT

CMP1 IN

−/0.6 REF

CMP1 IN+

CMP2 IN

−

CMP2 IN+/0.6 REF

GND

IN+

−

1.2V REF OUT

CMP1 OUT

CMP2 OUT

CMP2 DELAY

CMP1 RESET

Current Shunt

Monitor Output

1.2V REF

PULL−UP

4.7k

Ω

PULL−UP

4.7k

Ω

Transparent/Reset

Latch

Figure 2. INA20x Basic Connection

(1)

(2)

INA206 Datasheet(PDF) 11 Page - Texas Instruments

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