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2.2.4

Analog Inputs

2.2.5

Digital Outputs

Circuit Description

The EVM provides eight analog inputs, using an SMA connector for each of the eight channels of the

ADC. SMA channel inputs are J9, J10, J13, J14, J17, J18, J21, and J22. By default, the ADC accepts a

single-ended input and translates it to a differential signal using a Mini Circuits TC1-1T transformer. The

ADC inputs are dc-biased by feeding the ADC VCM voltage to the transformer center tap on the

secondary windings. Provisions have also been made on the EVM to allow for differential inputs using two

SMAs per input channel.

The serial LVDS digital outputs can be accessed through the J8 output connector. The EVM is designed

to be interfaced to the TI TSW1200 Rev B deserializer card, which plugs into J8. In addition, the EVM can

be interfaced to the ADSDeSer-50EVM using a translation card, the ADS5281DeSerAdapter. Both the

TSW1200 Rev B and the ADSDeSer-50EVM contain the required parallel 100-

Ω termination resistor that

must be placed at the receiver to terminate each LVDS data pair properly.

Note:

TSW1200 Rev B: Users wishing to use the TSW1200 for deserialization should note that the

minimium ADC sampling frequency this can be operated at is 32 MHz. The TSW1200 uses a

digital clock manager (DCM) with a minimium operational frequency of 32 MHz.

Full documentation on the TI ADSDeSer-50EVM deserializer is found in the ADSDeSer-50EVM Evaluation

Module User's Guide (SBAU091) and Connecting Xilinx FPGAs to Texas Instruments ADS527x Series

ADCs, Xilinx™ application report XAPP774. The VHDL deserializer source code can be found on the

Xilinx Web site.

SLAU205 – January 2008

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