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Configuring the Board

Configuring the Reference Inputs

The CDCUN1208LP offers two inputs (IN1 and IN2). SMA J4 and J5 are dedicated for IN1 (IN1p and

IN1n) and SMA J7 and J8 are dedicated for IN2 (IN2p and IN2n). Both inputs in the EVM are ac-coupled

as default by using coupling capacitors (C231 and C232 for IN1 and C235 and C236 for IN2). JMP7 and

JMP8 are used to set the input biasing and termination and should be configured according to the Input

Reference section of the EVM schematic.

All inputs have options for 50 Ω to GND. This 50 Ω to GND can be required if the signal generator is used

as input clock source.

Configuring the Control Pins

The device has multiple dedicated pins to control and configure the operation. Setting of these pins is

critical to operate the device correctly.

Mode Selection Pins (MODE): This pin will select the mode of device configuration. The Jumper on the

Header MODE (JP_3_20) is required to set based on Table 1.

Table 1. Mode Selection Jumper Settings

Jumper on MODE Header Mode of Configuration

GND SPI Mode

VDD I2C Mode

OPEN Pin Mode

Output Control Pin (OE): This pin can used to enable (HIGH) or disable (LOW) all outputs. For normal

operation, Header CLK_OE (JP_3_23) should be connected to VDD. Connect the Jumper to GND to

disable the outputs. This functionality is only available in pin mode.

Output Signaling Level Selection Pin (OTTP): This pin will select the signaling level of all outputs. The

header OTTP (JP_3_18) is dedicated for this pin. This pin is only available in pin mode.

Table 2. Mode Selection Jumper Settings

Jumper on OTTP Header Output Type

GND LVDS

VDD I2C Mode

OPEN LVCMOS

Output Edge Rate Control Pin (ERC): This pin will select the edge rate for all outputs. The Header

ADD_CS (JP_3_17) is dedicated for this pin. This pin is only available in pin mode.

Table 3. Edge Rate Control Jumper Settings

Jumper on OTTP Header Output Type

GND SLOW

VDD Medium

OPEN FAST

In I

C mode, this pin is used to set the host interface address.

IN2 Divider Setting Pin (DIVIDE): This pin will select the divider value of the IN2 input. The Header

DATA_DIV (JP_3_19) is dedicated for this pin. This pin is only available in pin mode.

Table 4. Edge Rate Control Jumper Settings

Jumper on DATA_DIV Header Output Type

GND /2

VDD /4

OPEN /1

SCAU050–May 2012 CDCUN1208LP Evaluation Board

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