Related Documentation From Texas Instruments - Texas Instruments ADS8481EVM User Manual

Table of Contents

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6.1

As a Reference Design

As a reference design, the ADS8481EVM contains the essential circuitry to showcase the analog-to-digital

converter. This essential circuitry includes the input amplifier, reference circuit, and buffers. The

ADS8481EVM analog input circuit is optimized for a wide bandwidth signal; therefore, the user may need

to adjust the input buffer circuitry to better suit your needs. In AC-type applications where signal distortion

is a concern, the user should use high quality capacitors such as Mica, polypropylene or COGs type

capacitors in the signal path. In applications where the input is multiplexed, the A/D input resistor and

capacitor may need to be adjusted further.

6.2

As a Prototype Board

As a prototype board, the ADS8481EVM features amplifiers in a standard 8-pin SOIC package and many

resistor pads scatter around allowing the user to experiment with a host of circuits, as needed. The

ADS8481EVM can be used to evaluate both dual- and single-supply amplifiers in both inverting and

non-inverting configurations. The ADS8481EVM comes installed with a dual-supply amplifier which allows

the user to take advantage of the full input voltage range of the converter. For applications that require

signal supply operation and smaller input voltage range, the THS4031 can be replaced with the

single-supply amplifier like the OPA300 or OPA350. Pad jumper SJP3 should be shorted between pads 1

and 2. This shorts the minus supply pin of the amplifier to ground. Positive supply voltage can be applied

at test point TP4 or at connector J5 pin 1.

6.3

As a Software Test Platform

As a software test platform, connectors P1, P2, and P3 plug into the parallel interface connectors of the

5-6K interface board. The 5-6K interface board sits on the C5000 and C6000 digital signal processor

starter kits (DSK). The ADS8481EVM is mapped then into the processor's memory space. The 5-6k

interface board also provides an area for signal conditioning. This area can be used to install application

circuit(s) for digitization by the ADS8481 analog-to-digital converter. For more information, see the 5-6K

Interface Board user's guide (SLAU104) .

For the software engineer, the ADS8481EVM provides a simple platform for interfacing to the converter.

The EVM provides standard 0.1-inch headers and sockets to wire into prototype boards. The user need

only provide three address lines (A2, A1, and A0) and address valid line (DC_CS) to connector P2. To

select which address combinations generate RD and CONVST, set jumpers as shown in

that the Chip Select (CS) signal is not memory-mapped or tied to P2; therefore, it must be controlled by a

general-purpose pin or shorted to ground at J3 pin 1. If address decoding is not required, the EVM

provides direct access to converter data bus by P3 and control by J3.

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