Datasheet
®
20
PCM3501
APPLICATIONS INFORMATION
BASIC CIRCUIT CONNECTIONS
The basic connection diagram for the PCM3501 is shown in
Figure 16. Included are the required power supply bypass and
reference decoupling capacitors. The DAC output, V
OUT
, and
the ADC input, V
IN
, should be AC-coupled to external cir-
cuitry.
Reference Pin Connections
The V
COM
voltage is used internally to bias the input and
output amplifier stages of the PCM3501. It is brought out
FIGURE 16. Basic Connection Diagram.
unbuffered on pin 1 for decoupling. A 1µF to 10µF alumi-
num electrolytic or tantalum capacitor is recommended for
decoupling purposes. This capacitor should be located as
close as possible to pin 1.
The V
COM
voltage is typically equal to V
CC
/2, and may be
used to bias external input and output circuitry. However,
since the V
COM
pin is not a buffered output, it must drive a
high impedance load to avoid excessive loading. Buffering
the V
COM
pin with an external op amp configured as a
voltage follower is recommended when driving multiple bias
nodes. Figure 17 shows an example of using V
COM
with
external circuitry.
FIGURE 17. Using V
COM
to Bias External Circuitry.
V
COM
V
REF
1
V
REF
2
V
IN+
V
IN–
M/S
TSC
BCK
FS
DIN
DOUT
FSO
V
CC
AGND
V
OUT+
V
OUT–
PDWN
LOOP
HPFD
XTI
XTO
SCKIO
DGND
V
DD
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
PCM3501
+
+
+
+
C
3
C
4
C
5
C
6
Serial
Interface
+
+
C
1
+3.3V
Power supply
External Reset
Power-Down Control
External Clock System
Analog Line Interface Circuit
Telecom Line
+
C
2
C
9
C
1
, C
2
: Power supply bypass capacitors. Parallel combination of 1µF to 10µF aluminum electrolytic capacitor and 0.1µF ceramic capacitor.
C
3
, C
4
, C
5
: V
REF
and V
COM
bypass capacitors. 1µF to 10µF aluminum electrolytic capacitor.
C
6
-C
9
: Input/output AC-coupling capacitors. 0.1µF to 10µF. If V
IN
+, V
IN
–, V
OUT
+, V
OUT
– are operated in reference
to V
COM
, these capacitors are not required.
+
C
7
+
C
8
PCM3501
OPA337
+
4.7µF
Use voltage follower
to buffer V
COM
To Bias
Nodes
V
COM