lm4546a National Semiconductor Corporation, lm4546a Datasheet - Page 12

• Manufacturer Part Number: lm4546a
• Description: Ac ?97 Rev 2 Multi-channel Audio Codec With Sample Rate Conversion And National 3d Sound
• Manufacturer: National Semiconductor Corporation

www.national.com
Pin Descriptions
V
3DP, 3DN
RESET#
DV
DV
DV
DV
REF_OUT
SYNC
Name
Name
Name
AV
AV
V
ID0#
ID1#
REF
DD1
DD2
SS1
SS2
DD
SS
33,34
Pin
Pin
Pin
10
11
45
46
25
26
27
28
1
9
4
7
I / O
I / O
I / O
O
O
O
I
I
I
I
I
I
I
I
I
I
(Continued)
AC Link frame marker and Warm Reset
This input defines the boundaries of AC Link frames. Each frame lasts 256 periods of
BIT_CLK. In normal operation SYNC is a 48 kHz positive pulse with a duty cycle of 6.25%
(16/256). SYNC is sampled on the rising edge of BIT_CLK and the codec takes the first
positive sample of SYNC as defining the start of a new AC Link frame. If a subsequent SYNC
pulse occurs within 255 BIT_CLK periods of the frame start it will be ignored.
SYNC is also used as an active high input to perform an (asynchronous) Warm Reset. Warm
Reset is used to clear a power down state on the codec AC Link interface.
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 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 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
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 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
bit to “0”. If left open (NC), ID1# is pulled high by an internal pull-up resistor.
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 (3.3 µF, 0.1 µF) this pin to
maximize codec performance. This pin must be tied to AV
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)
12
Functional Description
Functional Description
Functional Description
DD
with a 10 kΩ pull-up resistor.
DD
DD
will set the ID0
will set the ID1