lm4550 National Semiconductor Corporation, lm4550 Datasheet - Page 12

• Manufacturer Part Number: lm4550
• Description: Ac ?97 Rev 2.1 Multi-channel Audio Codec With Stereo Headphone Amplifier, Sample Rate Conversion And National 3d Sound
• Manufacturer: National Semiconductor Corporation

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Pin Descriptions
Typical Performance Characteristics
3DP, 3DN
AFILT2
Name
33,34
Pin
30
ADC Noise Floor
Analog Loopthru
Noise Floor
I / O
O
O
(Continued)
This pin is not used and should be left open (NC). However, a capacitor to ground on this pin
is permitted - it will not affect performance.
These pins are used to complete the National 3D Sound circuit. Connect a 0.022µF capacitor
between pins 3DP and 3DN. The National 3D Sound can be turned on and off via bit D13 in
control register 20h. This is a fixed-depth type stereo enhance circuit, thus writing to register
22h has no effect. If National 3D Sound is not needed, then these pins should be left as no
connect (NC).
POWER SUPPLIES AND REFERENCES (Continued)
10097215
10097218
12
Functional Description
DAC Noise Floor
ADC Frequency
Response
10097216
10097219