9 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification,

and TI does not warrant its accuracy or completeness. TI’s customers are responsible for

determining suitability of components for their purposes, as well as validating and testing their design

implementation to confirm system functionality.

9.1 Application Information

The PGA855 is a monolithic, high-voltage, high bandwidth, precision programmable gain instrumentation

amplifier with fully differential outputs. The PGA855 combines a high-speed current-feedback input stage with an

internally matched gain resistor network, followed by a four-resistor, fully differential amplifier output stage. The

PGA855 is equipped with 8 binary-gain settings, from 0.125 V/V to 16 V/V, using three digital gain-selection pins:

A0, A1, and A2.

The PGA855 is designed to work with applications such as factory automation and control, analog input

modules, data acquisition, test and measurement, and semiconductor test.

9.2 Typical Applications

9.2.1 ADS127L11, 24-Bit, Delta-Sigma ADC Driver Circuit

The application circuit in Figure 9-1 shows a schematic for a 24-bit wide-bandwidth, delta-sigma ADC. The

ADS127L11 ADC offers two digital filters to optimize ac applications (wideband filter) or dc applications (sinc4

filter). Table 9-2 and Table 9-3 show measurement results in both filter settings. For a detailed design procedure

to operate the ADS127L11 ADC, see the ADS127L11EVM-PDK evaluation module user's guide.

+

–

OUT+

IN

IN+

OUT

VOCM

5 k

5 k

5 k

5 k

ADS127L11

1x Input Range

INP

INN

FDA_IN

FDA_IN+

PGA855

+

–

VIN+

VIN

VO = G × (VIN+

VIN )

+

VO

Gain Network

A0

A1

A2

A0

A1

A2

DGND

DGND

VREF

AVDD

CFB

25 pF

CFB

25 pF

RFIL

47.4

RFIL

47.4

CDIFF

560 pF

CCM

51 pF

CCM

51 pF

1 k

1000 pF

ADS127L11

VCM Pin

VS+

VS

15 V

100 nF

5 V

5 V

15 V

100 nF

LVDD

LVSS

AVSS

4.096 V

RFIL_Optional

RFIL_Optional

CIN_DIFF

10 ×

CIN_CM

1 ×

CIN_CM

1 ×

100 nF

Figure 9-1. Driving the Delta-Sigma ADC ADS127L11

PGA855

SBOSAE0 – APRIL 2023

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