Texas Instruments ADS8688EVM-PDK, Руководство пользователя

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EVM Analog Interface
2.2 Using Onboard, Second-Order, Butterworth, Low-Pass Filters
The ADS8688EVM includes second-order, Butterworth, low-pass filters with a cutoff frequency of 22 kHz
for channels AIN0, AIN1, AIN2, and AIN3. There is also a provision to bypass these filters. See
Figure 1
for an analog input circuit for channels AIN0, AIN1, AIN2, and AIN3. Table 4 lists the jumper settings for
using onboard, second-order, Butterworth, low-pass filters and Table 5 lists the jumper settings for
bypassing these filters.
Table 4. Using Onboard, Second-Order, Butterworth, Low-Pass Filters
Channel Jumper Position Jumper Position
AIN0 J25 Closed J8 Closed between pins 1 and 2
AIN1 J31 Closed J10 Closed between pins 1 and 2
AIN2 J30 Closed J11 Closed between pins 2 and 3
AIN3 J15 Closed J9 Closed between pins 2 and 3
Table 5. Bypassing the Onboard, Second-Order, Butterworth, Low-Pass Filters
Channel Jumper Position Jumper Position
AIN0 J25 Open J8 Closed between pins 2 and 3
AIN1 J31 Open J10 Closed between pins 2 and 3
AIN2 J30 Open J11 Closed between pins 1 and 2
AIN3 J15 Open J9 Closed between pins 1 and 2
2.3 Selecting the Reference Mode for the ADS8688EVM
The ADS8688EVM can either operate on an internal or external reference. Table 6 lists the jumper
settings for selecting the reference. Table 7 describes the connections for the external reference.
Table 6. Selecting the Reference for the ADS8688EVM
Position for Using Internal
Jumper Reference Position for Using External Reference
J2 Closed Open
Table 7. External Reference Connections
Pin
Number Signal Description
J5.1 REFIN Input for external reference
J5.2 GND Analog ground connection
7 SBAU230A – August 2014 – Revised December 2014 ADS8688EVM-PDK Evaluation Module
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