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Configuring the Board

Each output buffer can be selected as LVDS, HCSL or a pair of LVCMOS outputs. One of the signal types

can be selected for each output or can be disabled by clicking on the output buffer box. If LVCMOS signal

type is selected, Enable boxes need to be checked to enable the outputs individually.

7 Configuring the Board

The CDCUN1208LP is a programmable clock buffer with many options. The EVM was designed with the

maximum flexibility so that the user can configure the EVM to operate in its desired mode.

Selecting the Interface Connection

The CDCUN1208LP can be configured via serial interface or through control pins. Switch SW17 should be

turned on to enable communication through USB to the SPI interface. This switch must be turned off for

Pin control mode. Switch SW18 must also be turned off.

Header JMP6 and JP_3_17 can also be used to connect external host to SPI/I

Configuring the Power Supply

The device can be powered up with external power supply or on-board regulators powered by USB cable

attached. The EVM has options for 1.8V, 2.5V and 3.3V power supplies. These supply voltages can be

external or internal from the regulators. It has also five different rails – four for output power supplies and

one for VDD.

The banana jacks P9, P10 and P11 are external 3.3V, 2.5V and 1.8V respectively. The banana jacks P8

and P12 are for GND. The LDOs U14, U15 and U16 generate 3.3V, 2.5V and 1.8V respectively. The

jumper on Header JP_3_24 selects between external or internal 3.3V, the jumper on Header JP_3_25

selects between external or internal 2.5V and the Jumper on Header JP_3_26 selects between external or

internal 1.8V.

The Jumpers on the Header JMP5 selects for VDD power rail, JMP1 selects for VDDOUT1, JMP2 selects

for VDDOUT2, JMP3 selects for VDDOUT3 and JMP4 selects for VDDOUT4 from 3.3V, 2.5V and 1.8V

power supplies. Using these Headers, the power supplies can be mixed for the device operation.

The figure below is an example of the configuration of the power supplies – all supplies are chosen from

3.3V internal regulators.

SCAU050–May 2012 CDCUN1208LP Evaluation Board

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