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DOUT PIN

FMT PIN

SYSTEM CLOCK

TYPICAL CIRCUIT CONNECTION DIAGRAM

S0013-01

1

2

3

4

5

6

7

14

13

12

11

10

9

8

Format

Latch Enable

Data Out

+

Pin Program

or Control

Audio

Data

Processor

Lch In

+5 V

C4(2)

VREF1

VREF2

AGND

VCC

FMT

BYPAS

DOUT

VINL

VINR

DGND

VDD

SCKI

BCK

LRCK

0 V

Bypass

+

C6(3)

+

C5(3)

Data Clock

System Clock

C3(2)

+

Rch In

C1(1)

C2(1)

PCM1801

SBAS131C – OCTOBER 2000 – REVISED JULY 2007

APPLICATION INFORMATION (continued)

The DOUT pin has a large load-drive capability, but locating a buffer near the PCM1801 and minimizing load

capacitance is recommended in order to minimize the digital-analog crosstalk and maximize the dynamic

performance of the ADC.

In general, the FMT pin is used for audio data format selection by tying up DGND or VDD in accordance with

interface requirements. If the application system cannot ensure an effective system clock prior to power up of

the PCM1801 when I2S format is required, then the FMT pin must be set HIGH after the power-on reset

sequence. This input control can be accomplished easily by connecting a C-R delay circuit with a delay time

greater than 1 ms to the FMT pin.

The quality of the system clock can influence dynamic performance in the PCM1801. The duty cycle, jitter, and

threshold voltage at the system clock input pin must be carefully managed. When power is supplied to the part,

the system clock, bit clock (BCK), and word clock (LRCK) should also be supplied simultaneously. Failure to

supply the audio clocks results in a power dissipation increase of up to three times normal dissipation and may

degrade long-term reliability if the maximum power dissipation limit is exceeded.

Figure 28 is a typical connection diagram illustrating a circuit for which the input HPF cutoff frequency is about

5 Hz.

(1)

C1 and C2: A 1-

μF capacitor gives a 5.3-Hz (τ = 1 μF * 30 k

Ω) cutoff frequency for the input HPF in normal operation

and requires a power-on setting time of 30 ms at power up.

(2)

C3 and C4: Bypass capacitors, 0.1-

μF ceramic and 10-μF tantalum or aluminum electrolytic, depending on layout

and power supply

(3)

C5 and C6: 4.7-

μF tantalum or aluminum electrolytic capacitors

Figure 28. Typical Circuit Connection

17

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