Datasheet

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APPLICATION INFORMATION
Connection Diagrams
Power Supplies and Grounding
Short-Circuit Protection
PCM1770 , PCM1771
SLES011E – SEPTEMBER 2001 – REVISED MARCH 2007
Figure 29 shows the basic connection diagram with the necessary power supply bypassing and decoupling
components. It is recommended that the component values shown in Figure 29 be used for all designs.
The use of series resistors (22 Ω to 100 Ω ) is recommended for the SCKI, LRCK, BCK, and DATA inputs. The
series resistor combines with the stray PCB and device input capacitance to form a low-pass filter that reduces
high-frequency noise emissions and helps to dampen glitches and ringing present on the clock and data lines.
The PCM1770 and PCM1771 devices require a 2.4-V typical analog supply for V
CC
and V
HP
. These 2.4-V
supplies power the DAC, analog output filter, and other circuits. For best performance, these 2.4-V supplies
must be derived from the analog supply using a linear regulator, as shown in Figure 29 .
Figure 29 shows the proper power supply bypassing. The 10-µF capacitors must be tantalum or aluminum
electrolytic, while the 0.1-µF capacitors are ceramic (X7R type is recommended for surface-mount applications).
Continuous shorting of H
OUT
L and H
OUT
R to GND, to a power supply, or to each other is not permitted, as
protection circuitry for an output short is not implemented in the device. If the possibility of shorting cannot be
eliminated in an application, an 8- Ω or higher series resistor must be added between the phase compensation
circuits of the H
OUT
x pins and the application circuitry (headphone jack in Figure 29 ).
29
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