Datasheet

Analog Interface

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2 Analog Interface

For maximum flexibility, the ADS8638EVM is designed for easy interfacing to multiple analog sources.

Samtec part numbers SSW-110-22-F-D-VS-K and TSM-110-01-T-DV-P provide a convenient 10-pin, dual

row header/socket combination at J1. This header/socket provides access to the analog input pins of the

ADC. Consult Samtec at www.samtec.com or call 1-800-SAMTEC-9 for a variety of mating connector

options. Table 1 shows the pinout of the analog input connector, J1.

Table 1. J1: Analog Interface Header

Pin Number Signal Description

J1.2 AIN7 / NC ADC analog input (AIN7: ADS8x38, NC: ADS8x34)

J1.4 AIN6 / NC ADC analog input (AIN6: ADS8x38, NC: ADS8x34)

J1.6 AIN5 / AIN3 ADC analog input (AIN5: ADS8x38, AIN3:

ADS8x34)

J1.8 AIN4 / AIN2 ADC analog input (AIN4: ADS8x38, AIN2:

ADS8x34)

J1.10 AIN3 / AIN1 ADC analog input (AIN3: ADS8x38, AIN1:

ADS8x34)

J1.12 AIN2 / AIN0 ADC analog input (AIN2: ADS8x38, AIN0:

ADS8x34)

J1.14 AIN1 / NC ADC analog input (AIN1: ADS8x38, NC: ADS8x34)

J1.16 AIN0 / NC ADC analog input (AIN0: ADS8x38, NC: ADS8x34)

J1.1-19 (odd) GND Analog ground connections (except J1.15)

J1.15 V

REFOUT

Buffered reference output

J1.18 NC —

J1.20 Ext V

REF

External reference voltage input

The eight ADC analog inputs (four inputs for ADS8x34 devices) are available at the J1 header. All of these

inputs, with the exception of one, are routed directly from the J1 header to the ADC. The AIN2/AIN0

channel includes an OPA140 to help drive one of the analog input channels to show the proper way to

drive the ADC. The op amp is in unity gain, and includes a RC low-pass filter component before reaching

the ADC.

An external reference can be applied to the ADC via an external source using pin J1.20. This signal is

routed directly to JP2 where it can be jumped in to the VREFP line.

An OPA379 is located on the EVM to buffer the reference signal and output it on J1.15.

ADS8638EVM-PDK SBAU192–July 2011

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