Datasheet

www.ti.com

560 (0.1%)W

40.2 (1%)W

270 (0.1%)W

OPA1632DGN

AnalogInput

Full-Scale:11.76V Differential

typicalwithR =40W

1nF

560 (0.1%)W

Ground

LiftSwitch

2.7nF

10nF 100nF-

-15V

OCM

VINL orVINR- -

VINL orVINR++

From

BufferedV

COM

10nF 100nF-

+15V

100nF

PCM4222

SBAS399A – OCTOBER 2006 – REVISED MARCH 2007

Figure 50. Differential Input Buffer Circuit Utilizing the OPA1632

Figure 51 demonstrates the same circuit topology of Figure 50 , while using standard single or dual op amps.

The noise level of this circuit is adequate for obtaining the typical A-weighted dynamic range performance for the

PCM4222. However, unweighted performance may suffer, depending upon the op amp noise specifications.

Near-typical THD+N can be achieved with this configuration, although this performance also depends on the op

amps used for the application. The NE5534A and OPA227 (the lower cost 'A' version) are good candidates from

a noise and distortion perspective, and are reasonably priced. More expensive lower-noise models, such as the

OPA211 , should also work well for this configuration. Feedback and input resistor values may be changed to

alter circuit gain. However, it is recommmended that all circuit changes be simulated and then tested on the

bench using a working prototype to verify performance.

Figure 52 illustrates a differential input circuit that employs a noninverting architecture. The total noise and

distortion is expected to be higher than that measured for Figure 50 and Figure 51 . As with Figure 51 , the

NE5534A and OPA227 are good candidates for this circuit, although similar op amps should yield equivalent

results.

A useful tool for simulating the circuits shown here is TINA-TI , a free schematic capture and SPICE-based

simulator program available from the Texas Instruments web site . This tool includes macro models for many TI

and Burr-Brown branded amplifiers and analog integrated circuits. TINA-TI runs on personal computers using

Microsoft Windows

operating systems.

Submit Documentation Feedback