CS3310_05 Datasheet, PDF (10/17 Pages) Cirrus Logic – Stereo Digital Volume Control

CS3310
PCB Layout, Grounding and Power Supply Decoupling
As with any high performance device which contains both analog and digital circuitry, careful at-
tention to power supply and grounding arrangements must be observed to optimize performance.
Figure 2 shows the recommended power arrangements with VA+ connected to a clean +5 volt
supply and VA- connected to a clean -5 volt supply. VD+ powers the digital interface circuitry and
should be powered from VA+, as shown in Figure 2, to avoid potentially destructive SCR latch-
up. Decoupling capacitors should be located as near to the CS3310 as possible, see Figure 5.
Figure 5. Recommended 2-Layer PCB Layout
Analog Ground Plane
+
10 µ F
10 Ω
10 µ F
+
VA+
0.1 µ F
VA-
10 µ F
+
0.1 µ F
0.1 µ F
The printed circuit board layout should have separate analog and digital regions with individual
ground planes. The CS3310 should reside in the analog region as shown in Figure 5. Care
should be taken to ensure that there is minimal resistance in the analog ground leads to the de-
vice to prevent any change in the defined attenuation settings. Extensive use of ground plane fill
on both the analog and digital sections of the circuit board will yield large reductions in radiated
noise effects.
Performance Plots
Figure 8 displays the CS3310 frequency response with a 3.75 Vp output.
Figure 9 shows the frequency response with a 0.375 Vp output.
Figure 6 is the Total Harmonic Distortion + Noise vs. amplitude at 1 kHz. The upper trace is the
THD+N vs. amplitude of the CS3310 The lower trace is the THD+N of the Audio Precision Sys-
tem One generator output connected directly to the analyzer input. The System One panel set-
tings are identical to the previous test. This indicates that the THD+N contribution of the Audio
Precision actually degrades the measured performance of the CS3310 below 2.7 Vrms signal
levels.
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DS82F1