Datasheet

560 (0.1%)W
2
3
G
1
R
T
S
40.2 (1%)W
40.2 (1%)W
270 (0.1%)W
270 (0.1%)W
OPA1632DGN
AnalogInput
Full-Scale:11.76V Differential
PP
TypicalwithR =40W
S
1nF
1nF
560 (0.1%)W
Ground
LiftSwitch
2.7nF
10nF 100nF-
-15V
2
1
8
EN
V
OCM
VINL orVINR- -
VINL orVINR++
From
BufferedV
COM
7
6
3
4
5
10nF 100nF-
+15V
100nF
PCM4220
www.ti.com ............................................................................................................................................. SBAS407C – DECEMBER 2006 – REVISED AUGUST 2009
film or C0G ceramic capacitors; both types perform with equivalent results in this application. Surface-mount
devices are utilized throughout because they provide superior performance when combined with a wideband
amplifier such as the OPA1632 . The DGN package version of the OPA1632 is utilized; this package includes a
thermal pad on the bottom side. The thermal pad must be soldered to the PCB ground plane for heat sink and
mechanical support purposes.
Figure 45. Differential Input Buffer Circuit Utilizing the OPA1632
Figure 46 demonstrates the same circuit topology of Figure 45 , 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
PCM4220. 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 recommended that all circuit changes be simulated and then tested on the bench
using a working prototype to verify performance.
Figure 47 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 45 and Figure 46 . As with Figure 46 , 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 (Windows 2000 or newer).
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Product Folder Link(s): PCM4220