lm4549b National Semiconductor Corporation, lm4549b Datasheet - Page 13

• Manufacturer Part Number: lm4549b
• Description: Ac ?97 Rev 2.1 Multi-channel Audio Codec With Sample Rate Conversion And National 3d Sound
• Manufacturer: National Semiconductor Corporation

Pin Descriptions
V
3DP, 3DN
RESET#
DV
DV
REF_OUT
DV
DV
Name
EAPD
Name
Name
AV
AV
ID0#
ID1#
V
REF
DD1
DD2
SS1
SS2
DD
SS
33,34
Pin
Pin
Pin
11
45
46
47
25
26
27
28
1
9
4
7
I / O
I / O
I / O
O
O
O
O
I
I
I
I
I
I
I
I
I
(Continued)
Cold Reset
This active low signal causes a hardware reset which returns the control registers and all
internal circuits to their default conditions. RESET# MUST be used to initialize the LM4549B
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 are of inverted polarity relative to 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
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 are of inverted polarity relative to 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
the ID1 bit to “0”. If left open (NC), ID1# is pulled high by an internal pull-up resistor.
External Amplifier Power Down control signal
This output is set by the EAPD bit (bit D15) in the Powerdown Control/ Status register, 26h.
As with the other logic outputs, the output voltage is set by DV
connected to the shutdown pin on an external power amplifier. For normal operation the
default value of EAPD = 0 will enable the external amplifier allowing an input on PC_BEEP to
be heard during Cold Reset.
Analog supply
Analog ground
Digital supply
Digital supply
Digital ground
Digital ground
Nominal 2.2 V internal reference
Not intended to sink or source current. Use short traces to bypass (3.3µF, 0.1µF) this pin to
maximize codec performance. See text.
Nominal 2.2 V reference output
Can source up to 5 mA of current and can be used to bias a microphone.
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 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).
DIGITAL I/O AND CLOCKING (Continued)
POWER SUPPLIES AND REFERENCES
3D SOUND AND NO-CONNECTS (NC)
13
Functional Description
Functional Description
Functional Description
DD
. This pin is intended to be
www.national.com
DD
DD
will set
will set