192 kHz Stereo Asynchronous
Sample Rate Converter
a
AD1896*
FUNCTIONAL BLOCK DIAGRAM
FEATURES
Automatically Senses Sample Frequencies
No Programming Required
GRPDLYS RESET VDD_IO VDD_CORE
Attenuates Sample Clock Jitter
3.3 V–5 V Input and 3.3 V Core Supply Voltages
Accepts 16-/18-/20-/24-Bit Data
Up to 192 kHz Sample Rate
Input/Output Sample Ratios from 7.75:1 to 1:8
Bypass Mode
Multiple AD1896 TDM Daisy-Chain Mode
Multiple AD1896 Matched-Phase Mode
142 dB Signal-to-Noise and Dynamic Range
(A-Weighted, 20 Hz–20 kHz BW)
Up to –133 dB THD + N
AD1896
MUTE_I
FS
OUT
SDATA_I
SCLK_I
LRCLK_I
FIFO
SDATA_O
SCLK_O
LRCLK_O
FS
IN
SERIAL
INPUT
SMODE_IN_0
SMODE_IN_1
SMODE_IN_2
TDM_IN
SERIAL
OUTPUT
FIR
FILTER
SMODE_O_0
SMODE_O_1
DIGITAL
PLL
BYPASS
MUTE_O
WLNGTH_O_0
WLNGTH_O_1
CLOCK DIVIDER
MSMODE_0
ROM
Linear Phase FIR Filter
Hardware Controllable Soft Mute
Supports 256 ꢀ fS, 512 ꢀ fS, or 768 ꢀ fS Master
Mode Clock
MCLK_I
MSMODE_2
MCLK_O
MSMODE_1
Flexible 3-Wire Serial Data Port with Left-Justified,
I2S, Right-Justified (16-,18-, 20-, 24-Bits), and
TDM Serial Port Modes
Master/Slave Input and Output Modes
28-Lead SSOP Plastic Package
port supports TDM mode for daisy-chaining multiple AD1896s to
a digital signal processor. The serial output data is dithered down
to 20, 18, or 16 bits when 20-, 18-, or 16-bit output data is se-
lected. The AD1896 sample rate converts the data from the
serial input port to the sample rate of the serial output port. The
sample rate at the serial input port can be asynchronous with
respect to the output sample rate of the output serial port. The
master clock to the AD1896, MCLK, can be asynchronous to
both the serial input and output ports.
APPLICATIONS
Home Theater Systems, Studio Digital Mixers,
Automotive Audio Systems, DVD, Set-Top Boxes,
Digital Audio Effects Processors, Studio-to-Transmitter
Links, Digital Audio Broadcast Equipment,
DigitalTape Varispeed Applications
MCLK can be generated either off-chip or on-chip by the AD1896
master clock oscillator. Since MCLK can be asynchronous to the
input or output serial ports, a crystal can be used to generate
MCLK internally to reduce noise and EMI emissions on the
board. When MCLK is synchronous to either the output or input
serial port, the AD1896 can be configured in a master mode where
MCLK is divided down and used to generate the left/right
and bit clocks for the serial port that is synchronous to MCLK.
The AD1896 supports master modes of 256 ¥ fS, 512 ¥ fS,
and 768 ¥ fS for both input and output serial ports.
PRODUCT OVERVIEW
The AD1896 is a 24-bit, high performance, single-chip, second-
generation asynchronous sample rate converter. Based on Analog
Devices experience with its first asynchronous sample rate
converter, the AD1890, the AD1896 offers improved performance
and additional features. This improved performance includes a
THD + N range of –117 dB to –133 dB depending on the sample
rate and input frequency, 142 dB (A-Weighted) dynamic range,
192 kHz sampling frequencies for both input and output sample
rates, improved jitter rejection, and 1:8 upsampling and 7.75:1
downsampling ratios. Additional features include more serial
formats, a bypass mode, better interfacing to digital signal pro-
cessors, and a matched-phase mode.
Conceptually, the AD1896 interpolates the serial input data by
a rate of 220 and samples the interpolated data stream by the
output sample rate. In practice, a 64-tap FIR filter with 220
polyphases, a FIFO, a digital servo loop that measures the time
difference between the input and output samples within 5 ps,
and a digital circuit to track the sample rate ratio are used to
perform the interpolation and output sampling. Refer to the
Theory of Operation section. The digital servo loop and sample
rate ratio circuit automatically track the input and output
sample rates.
The AD1896 has a 3-wire interface for the serial input and
output ports that supports left-justified, I2S, and right-justified
(16-, 18-, 20-, 24-bit) modes. Additionally, the serial output
*Patents pending.
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REV. A
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