REV. 0

AD5532

–15–

APPLICATION CIRCUITS

AD5532 in a Typical ATE System

The AD5532 is ideally suited for use in Automatic Test Equipment.

Several DACs are required to control pin drivers, comparators,

active loads and signal timing. Traditionally, sample-and-hold

devices were used in this application.

The AD5532 has several advantages: no refreshing is required,

there is no droop, pedestal error is eliminated and there is no

need for extra filtering to remove glitches. Overall a higher level

of integration is achieved in a smaller area (see Figure 24).

DACs

ACTIVE

LOAD

DRIVER

COMPARATOR

FORMATTER

COMPARE

REGISTER

STORED

DATA

AND INHIBIT

PATTERN

PERIOD

GENERATION

AND

DELAY

TIMING

SYSTEM BUS

DAC

PARAMETRIC

MEASUREMENT

UNIT

SYSTEM BUS

DUT

DAC

DAC

DAC

DAC

DAC

DAC

Figure 24. AD5532 in an ATE System

Typical Application Circuit (SHA Mode)

The AD5532 can be used to set up voltage levels on 32 channels

as shown in the circuit below. An AD780 provides the 3 V refer-

ence for the AD5532, and for the AD5541 16-bit DAC. A simple

3-wire interface is used to write to the AD5541. The DAC output

and REFIN when laying out this circuit.

AD5532*

OFFS_IN

OFFS_OUT

REFIN

SCLK

DIN

SYNC

AD820

CS

DIN

SCLK

*ADDITIONAL PINS OMITTED FOR CLARITY

AD780*

AD5541*

REF

Figure 25. Typical Application Circuit

POWER SUPPLY DECOUPLING

In any circuit where accuracy is important, careful consideration

of the power supply and ground return layout helps to ensure

the rated performance. The printed circuit board on which the

AD5532 is mounted should be designed so that the analog and

digital sections are separated, and confined to certain areas of

the board. If the AD5532 is in a system where multiple devices

require an AGND-to-DGND connection, the connection should

be made at one point only. The star ground point should be

established as close as possible to the device. For supplies with

together. The AD5532 should have ample supply bypassing of

10

µF in parallel with 0.1 µF on each supply located as close to

the package as possible, ideally right up against the device. The

10

µF capacitors are the tantalum bead type. The 0.1 µF capacitor

should have low Effective Series Resistance (ESR) and Effective

Series Inductance (ESI), like the common ceramic types that

provide a low impedance path to ground at high frequencies, to

handle transient currents due to internal logic switching.

The power supply lines of the AD5532 should use as large a trace

as possible to provide low impedance paths and reduce the

effects of glitches on the power supply line. Fast switching signals

such as clocks should be shielded with digital ground to avoid

radiating noise to other parts of the board, and should never be

run near the reference inputs. A ground line routed between

(not required on a multilayer board as there will be a separate

ground plane, but separating the lines will help). It is essential

Avoid crossover of digital and analog signals. Traces on opposite

sides of the board should run at right angles to each other. This

reduces the effects of feedthrough through the board. A microstrip

technique is by far the best, but not always possible with a double-

sided board. In this technique, the component side of the board

is dedicated to ground plane while signal traces are placed on

the solder side.