CS4328 Datasheet, PDF (22/31 Pages) Cirrus Logic – 18-Bit, Stereo D/A Converter for Digital Audio

CDB4328
Power Supply Circuitry
Offset Calibration & Reset Circuitry
Figure 1 shows the evaluation board power sup-
ply circuitry. Power is supplied to the evaluation
board by five binding posts. The +5 V analog
power supply inputs of the converter are derived
from + 15 V using the voltage regulators U5 and
U6. The +5 V digital supply for the converter
and the discrete logic on the board is provided
by the +5 V and DGND binding posts. D1, D2,
and D3 are transient suppressors which also pro-
vide protection from incorrectly connected
power supply leads. C1-C8 provide general
power supply filtering for the analog supplies.
As shown in Figure 2, C20-C24 provide local-
ized decoupling for the converter VA+ and VA-
pins. Note that C22 is connected between VA-
and VA+ and not VA- and AGND. The evalu-
ation board uses both an analog and a digital
ground plane which are connected at J1. This
ground plane arrangement isolates the board’s
digital logic from the analog circuitry.
Figure 1, shows the offset calibration circuit pro-
vided on the evaluation board. Upon power-up,
this circuit provides a pulse on the Digital to
Analog Converter’s RST pin initiating an offset
calibration cycle. Pressing and releasing S2 also
initiates an offset calibration cycle.
Serial Data Interface
Figure 1 shows that there are two options for in-
puting serial data into the CS4328. Serial data
can be provided via the SDATA BNC connector
on the evaluation board. BNC connectors for
SCLK, the serial data input clock, and L/R, the
clock that defines the channel and delineates the
data, are also provided on the evaluation board.
This information can also be provided by the on-
board CS8412. JP3 selects the source of
SDATA, SCLK, and L/R that will be provided to
the converter. JP3 selections are shown in Ta-
ble 1.
+15V
AGND
-15V
+5V
DGND
D2 ^{+ C3}
47 uF
U5
IN 78L05 OUT
COM
C6
0.22 uF
+ C4
D3 _{47 uF}
C5
0.22 uF
IN
COM
79L05 OUT
U6
D2 = D3 = 1N6276A 1.5KE
D1 = P6KE-6V8P from Thomson
D1 ^{+ C1}
47 uF
VD+
C2
0.1 uF
D13
1N148
S2
CAL
C7
0.47 uF
VA+
J1
C8
AGND DGND
0.47 uF
VA-
VD+
5
U7C
6 _RST
CS4328
0.1uF
C15
R4
10kΩ
3
4
U7B
74HC14
Figure 1. Power Supply and Reset Circuitry
22
DS62DB2