CS5126 Cirrus Logic, CS5126 Datasheet - Page 22

• Manufacturer Part Number: CS5126
• Description: 16-Bit Stereo A/D Converter for Digital Audio
• Manufacturer: Cirrus Logic

Power Supplies
Figure 1 shows the power supply arrangements.
The analog section of the board is powered by
the ADC. A separate +5 V digital supply is re-
quired to power the discrete logic. Be sure to
switch on the
fore, the + 5 V logic supply. This will make sure
that the CLK and other logic signal are not driv-
ing the part before it is powered.
Analog Input
The analog input range is either
polar mode or 0 V to +V
The voltage reference is factory set to the recom-
mended value of +4.5 volts, so the typical input
signal ranges become
V.
22
15 volts, which is regulated down to
15 V at the same time as, or be-
Analog
Digital
+15V
Logic
0V
-15V
0V
+5V
4.5 volts or 0 V to +4.5
ref
in the unipolar mode.
D1
D2
D3
TP16
+15V
-15V
V
+ C20
+
+ C27
ref
47 F
C21
47 F
47 F
in the bi-
Figure 1. Power Supplies
5 V for
C26
0.1 F
C22
0.22 F
C24
0.22 F
IN
IN
+5VL
78L05
79L05
The source driving the analog inputs should have
a low (< 200
ance. Be careful not to overdrive the inputs
outside the power supplies of the ADC ( 5 V).
Figure 2 shows the buffer circuit used at the
Crystal factory to drive the ADC when perform-
ing FFT testing. See the CS5126 data sheet for
example FFT test results.
Voltage Reference
As shown in Figure 3, an LT1019-5 voltage ref-
erence provides a stable 4.5 V reference for the
ADC. An optional OP27 buffer filters out excess
reference noise and provides a very low output
impedance. To try the unbuffered LT1019-5 di-
rectly, solder in J2 and cut the VREF trace.
Alternatively the shunt reference based reference
schematic given in the CS5126 data sheet can be
evaluated by adding it to the analog patch area.
COM
COM
U4
U5
OUT
OUT
C23
0.47 F
C25
0.47 F
at high frequency) output imped-
J1
+5VA
-5VA
CDB5126
DS32DB5