3

dc934af

DEMO MANUAL DC934A

HarDware setup

CA0, CA1, CA2 pins. The demo software uses the global

the QuikEval™ software. They can be used in prototyping

ANALOg CONNECTIONS

terminals of the LTC2607 and LTC2422 ADC. When one of

theonboardreferencesisbeingused,thereferencevoltage

may be monitored at this point. An external reference may

also be applied to this turret after removing JP1.

grounding and Power Connections

the power supply on DC590 must be disabled! Refer to

DC590 Quick Start Guide for more details on this mode

of operation.

grounding: Separate power and signal grounds are pro-

vided. Any large currents drawn from the DAC outputs

should be returned to power ground. Also, if an external

power supply is connected, power ground should be

used. Signal ground is connected to the exposed ground

planes at the top and bottom edges of the board, and to

the two turrets labeled GND. Use signal ground as the

reference point for measurements and connections to

external circuits.

experiments

The following experiments are intended to demonstrate

some of the outstanding features of the LTC2607. All can

be performed using the onboard LTC2422 to monitor

the DAC output voltage. The indicated output voltage will

typically agree with an HP3458A voltmeter to 5 digits. If

a DAC will be sinking or sourcing a significant current,

then the output voltage should be measured as close to

the DAC as possible.

Most of the data sheet specifications use a 4.096V refer-

ence, so this is the preferred reference to use for these

which may affect the full-scale error. Selecting the 5V ref-

total current that the LTC2607 can source will be limited

to approximately 5mA.

Usinganexternalpowersupplyishighlyrecommendedfor

these experiments, especially those that draw significant

current. Refer to the DC590 quick start guide for details.

RESOLUTION

The onboard LTC2422 ADC has an input resolution of

Set the DAC output to a voltage close to mid-scale. Select

the FINE slider on the control panel with the mouse and

use the right and left arrow keys to step the output by

single LSBs. The change should be clearly visible in the

output graph. (It may be necessary to wait for the graph

to clear if a large step has just occurred.)

INTEgRAL NONLINEARITy

AroughmeasurementofINLcanbetakenusingtheonboard

ADC. Measure one of the LTC2607 outputs at code 256

and 65,535 and calculate the slope and intercept using a

spreadsheet. Next, take several readings at intermediate

points. The readings should not deviate from the calcu-

lated line by more than 64LSBs, and they will typically be

within 12LSBs.

LOAD REgULATION/DC OUTPUT IMPEDANCE

mid-scale (code 32768). Source or sink 15mA from one

with an appropriate value resistor. The voltage change