AD8426

Preliminary Technical Data

Rev. PrD | Page 16 of 20

PRECISION STRAIN GAGE

make it an excellent candidate for bridge measurements. The

bridge can be connected directly to the inputs of the amplifier

(see Figure 15).

5V

2.5V

10µF

0.1µF

AD8426

+IN

–IN

350Ω

350Ω

350Ω

350Ω

+

–

Figure 15. Precision Strain Gage

DRIVING AN ADC

Figure 16 shows several different methods of driving an ADC.

example because it has an unbuffered, charge sampling

architecture that is typical of most modern ADCs. This type of

architecture typically requires an RC buffer stage between the

ADC and the amplifier to work correctly.

Option 1 shows the minimum configuration required to drive

a charge sampling ADC. The capacitor provides charge to the

constant of the resistor and capacitor needs to stay above 5 μs.

This circuit is mainly useful for lower frequency signals.

Option 2 shows a circuit for driving higher frequency signals.

width and output drive. This amplifier can drive a resistor and

capacitor with a much higher time constant and is, therefore,

suited for higher frequency applications.

run off a large voltage supply, but drives a single supply ADC.

this circuit, because the 10 kΩ resistor between the two

AD8426

REF

100nF

100Ω

10kΩ

10Ω

10nF

ADC0

ADC1

ADC2

AGND

3.3V

3.3V

3.3V

OPTION 1: DRIVING LOW FREQUENCY SIGNALS

OPTION 2: DRIVING HIGH FREQUENCY SIGNALS

OPTION 3: PROTECTING ADC FROM LARGE VOLTAGES

3.3V

AD8426

AD8616

ADuC7026

REF

3.3V

10Ω

10nF

AD8426

AD8616

REF

+15V

–15V

Figure 16. Driving an ADC