AD1984

Rev. 0

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Page 11 of 20

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January 2007

FILTER/REFERENCE

MIC_BIAS-B

MIC_BIAS-C

27

28

29

O

O

O

Voltage Reference Filter.

Switchable Microphone Bias. For use with Port B (Pins 21, 22).

Switchable Microphone Bias. For use with Port C (Pins 23, 24).

Both MIC bias pins are capable of Hi-Z, 0 V, 1.65 V, 3.7 V, and 3.9 V (with 5.0 V on

Pin 33), Hi-Z, 0 V, 1.65 V, 2.86 V, and 3.0 V (with 3.3 V on Pin 33).

1

O

CAUTION: DO NOT APPLY 3.3 V TO THIS PIN!

Filter connection for internal core voltage regulator. This pin must be connected to

filter caps: 10

μF, 1.0 μF, and 0.1μF connected in parallel between Pin 1 and

POWER AND GROUND

3

I

Link Digital I/O Voltage Reference. 3.3 V

7

I

Digital supply return (ground).

9

I

internal digital core internal to the AD1984.

25, 38

I

CAUTION: DO NOT APPLY 5 V TO THESE PINS!

Analog supply voltage 3.3 V ONLY.

audio performance.

MIC_BIAS_IN

5.0 V or 3.3 V

33

I

Source power for microphone bias boost circuitry.

Connect this pin to 5.0 V via a low-pass filter. When connected this way the AD1984 is

capable of providing +3.9 V as a mic bias to all of the mic bias pins (except on

Pin 31).

26, 42

I

trace under, or close to, the AD1984.

Table 3. AD1984 Pin Descriptions (Continued)

Mnemonic

Pin No.

I/O

Description

The symbols used in this table are defined as: I = Input, O = Output, LI = Line Level Input, LO = Line Level Output, HP = Output capable of

driving headphone load, MIC = Input supports microphones with MIC bias and boost amplifier.