LM4546A Datasheet, PDF (12/28 Pages) National Semiconductor (TI) – AC 97 Rev 2 Multi-Channel Audio Codec with Sample Rate Conversion and National 3D Sound

Name
RESET#
ID0#
ID1#
Pin
I/O
Functional Description
Cold Reset
This active low signal causes a hardware reset which returns the control registers and all internal
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I
circuits to their default conditions. RESET# MUST be used to initialize the LM4546A after Power
On when the supplies have stabilized. Cold Reset also clears the codec from both ATE and Vendor
test modes. In addition, while active, it switches the PC_BEEP mono input directly to both channels
of the LINE_OUT stereo output.
Codec Identity
ID1# and ID0# determine the Codec Identity for multiple codec use. The Codec Identity configures
the codec in either Primary or one of three Secondary Codec modes. These Identity pins have the
45
I same polarity as the Codec Identity bits ID1, ID0 (bits D15, D14) in the read-only Extended Audio
ID register, 28h. If the ID0# pin (pin 45) is connected to ground then the ID0 bit (D14, reg 28h) will
be set to “1”. Similarly, connection to DV_DD will set the ID0 bit to “0”. If left open (NC), ID0# is pulled
high by an internal pull-up resistor.
Codec Identity
ID1# and ID0# determine the codec address for multiple codec use. The Codec Identity configures
the codec in either Primary or one of three Secondary Codec modes. These Identity pins have the
46
I same polarity as the Codec Identity bits ID1, ID0 (bits D15, D14) in the read-only Extended Audio
ID register, 28h. If the ID1# pin (pin 46) is connected to ground then the ID1 bit (D15, reg 28h) will
be set to “1”. Similarly, connection to DV_DD will set the ID1 bit to “0”. If left open (NC), ID1# is pulled
high by an internal pull-up resistor.
Name
AV_DD
AV_SS
DV_DD1
DV_DD2
DV_SS1
DV_SS2
V_REF
V_{REF_OUT}
POWER SUPPLIES AND REFERENCES
Pin
I/O
Functional Description
25
I Analog supply
26
I Analog ground
1
I Digital supply
9
I Digital supply
4
I Digital ground
7
I Digital ground
Nominal 2.2 V internal reference
27
O Not intended to sink or source current. Use short traces to bypass (3.3 µF, 0.1 µF) this pin to
maximize codec performance. This pin must be tied to AV_DD with a 10 kΩ pull-up resistor.
28
O
Nominal 2.2 V reference output
Can source up to 5 mA of current and can be used to bias a microphone.
Name
3DP, 3DN
NC
Pin
33,34
14–17
29–32
38–44
47, 48
3D SOUND AND NO-CONNECTS (NC)
I/O
Functional Description
These pins are used to complete the National 3D Sound stereo enhancement circuit. Connect a
0.022 µF capacitor between pins 3DP and 3DN. National 3D Sound can be turned on and off via
O the 3D bit (D13) in the General Purpose register, 20h. National 3D Sound uses a fixed-depth type
stereo enhancement circuit hence the 3D Control register, 22h is read-only and is not
programmable. If National 3D Sound is not needed, these pins should be left open (NC).
These pins are not used and should be left open (NC).
NC For second source applications these pins may be connected to a noise-free supply or ground
(e.g. AV_DD or AV_SS), either directly or through a capacitor.
Typical Performance Characteristics
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200308 Version 5 Revision 1 Print Date/Time: 2009/07/15 15:26:52