LT6106

9

6106fa

APPLICATIONS INFORMATION

Output Error Due to the Amplifier DC Offset

EV

R

R

OUT VOS

OS

OUT

IN

()

•

=

The DC offset voltage of the amplifier adds directly to the

error of the system and it limits the low end of the dynamic

range. The paragraph “Selection of External Current Sense

Resistor” provides details.

E

R

SENSE

R

IN

–I

B

–

⎛

⎝⎜

⎞

⎠⎟

It is convenient to refer the error to the input:

connected as shown in Figure 4. Under both conditions:

the 60μV error above is reduced to 6μV.

not necessary.

Output Error Due to Gain Error

The LT6106 exhibits a typical gain error of –0.25% at 1mA

output current. The primary source of gain error is due to

the finite gain to the PNP output transistor, which results in

Minimum Output Voltage

The curves of the Output Voltage vs Input Sense Voltage

show the behavior of the LT6106 with low input sense volt-

be slightly positive, the result of input offset voltages and

of a small amount of quiescent current (0.7μA to 1.2μA)

flowing through the output device. The minimum output

voltage in the Electrical Characteristics table include both

these effects.

Power Dissipation Considerations

The power dissipated by the LT6106 will cause a small

increase in the die temperature. This rise in junction tem-

perature can be calculated if the output current and the

supply current are known.

The power dissipated in the LT6106 due to the output

signal is:

The power dissipated due to the quiescent supply current is:

The total power dissipated is the output dissipation plus

the quiescent dissipation:

The junction temperature is given by:

At the maximum operating supply voltage of 36V and the

maximum guaranteed output current of 1mA, the total

Figure 4. Second Input R Minimizes Error Due to Input Bias Current

LT6106

6106 F04

–

+

LOAD

OUT

–IN

+IN