MAX5876/MAX5877/MAX5878 Evaluation Kits

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The MAX5876/MAX5877/MAX5878 EV kits provide head-

er connectors J1 and J2 to interface with a pattern gen-

erator, circuitry that converts the differential current

outputs to single-ended voltage signals, and circuitry to

convert a user-supplied single-ended clock signal to a

differential clock signal. The EV kit circuit also includes

an external 1.25V reference source U2 (MAX6161) and

a test point connector that can be used to overdrive the

MAX5876/MAX5877/MAX5878 internal 1.2V bandgap

reference. The EV kit board layout separates the circuit

power into digital, analog, and clock planes to improve

dynamic performance. The input data PC traces are

100

Ω differential controlled impedance and the analog

output PC traces are 50

Ω controlled impedance.

Power Supplies

The MAX5876/MAX5877/MAX5878 EV kits operate from

a single 1.8V power supply connected to the DVDD1

and AVDD1 input power pads, and a single 3.3V power

supply connected to the DVDD2, AVDD2, and VDD_CK

input power pads for simple operation. However, five

separate power supplies are recommended to optimize

dynamic performance. The EV kit PCB layout is divided

into three sections: digital, analog, and clock. Using sep-

arate power supplies for each section reduces noise and

improves the integrity of the analog output signal. When

using separate power supplies, connect a 1.8V power

supply across the DVDD1 and DGND pads and a 3.3V

power supply across DVDD2 and DGND pads (digital).

Connect a 1.8V power supply across the AVDD1 and

AGND pads and a 3.3V power supply across AVDD2

and AGND pads (analog). Connect a 3.3V power supply

across VDD_CK and GND_CK pads (clock).

LVDS Digital Input Data

The MAX5876/MAX5877/MAX5878 EV kits provide two

0.1in, 2 x 20 headers (J1, J2) to interface an LVDS pat-

tern generator to the EV kit. The header data pins are

labeled on the PCB with their appropriate LVDS data bit

designator. Use the labels on the EV kit board to match

the data bits from the pattern generator to the corre-

sponding data pins on headers J1 and J2. The input

data is latched on the rising edge of the clock signal.

The MAX5876/MAX5877/MAX5878 SELIQ and XOR func-

tions can also be controlled by applying an LVDS logic

signal to the J1 header pins labeled SELIQP, SELIQN,

XORP, and XORN. Refer to the LVDS-Compatible Digital

Inputs section in the MAX5876/MAX5877/MAX5878 IC

data sheets for detailed information on the SELIQ and

XOR functions. When using the XOR function, install a

100

Ω resistor at the EV kit R14 PCB pad.

Clock Signal

The MAX5876/MAX5877/MAX5878 operate with a differ-

ential clock input signal. However, the EV kit boards only

require an external single-ended clock signal connected

to the CLK SMA connector. The EV kits feature circuitry

that converts the single-ended clock signal to a differen-

tial clock signal. The clock signal can be either a sine or

a square wave. A minimum signal power amplitude of

+8dBm is recommended to drive the clock input. The

MAX5876/MAX5877/MAX5878 accept a clock input fre-

quency in the 2MHz to 500MHz range.

Two’s-Complement/Offset-Binary

Input Format

The two’s-complement or offset-binary input modes of

the MAX5876/MAX5877/MAX5878 are configured with

jumper JU2. Apply either a two’s-complement or offset-

binary formatted input pattern to connectors J1 and J2.

See Table 1 for the jumper JU2 configuration.

Reference Voltage

The MAX5876/MAX5877/MAX5878 require a reference

voltage to set the full-scale output current of the DAC.

The MAX5876/MAX5877/MAX5878 integrate a stable on-

chip bandgap reference of 1.2V that is selected by

default during initial power-up. An external voltage ref-

erence must be connected to test point TP1 when the

internal voltage reference is overdriven. The EV kits cir-

cuit also features an on-board, external 1.25V voltage

reference (U2, MAX6161) that can be used to overdrive

the internal bandgap reference. U2 has a tighter volt-

age-output tolerance and is less susceptible to temper-

ature variations. See Table 2 to select the voltage refer-

ence source.

Full-Scale Output Current

The MAX5876/MAX5877/MAX5878 require an external

resistor to set the full-scale output current. The

MAX5876/MAX5877/MAX5878 EV kits full-scale current

are set to 20mA with resistor R7 (2k

Ω). Replace resistor

R7 to adjust the full-scale output current. Refer to the

Reference Architecture and Operation section in the

MAX5876/MAX5877/MAX5878 IC data sheets to select

different values for resistor R7.