Datasheet

EVAL-AD1940AZ Preliminary Technical Data
Rev. PrA | Page 8 of 30
F
s
= 48 kHz. In order to set up the AD1940 PLL in 256×F
s
mode,
switch SW1 must be set up as shown in .
1234
AD1940
MODE SELECTION
SW1
PLL-CTRL0
PLL-CTRL1
PLL-CTRL2
ADR-SEL
Figure 7. PLL Mode Selection for 12.288 MHz Master Clock
A description of all possible PLL settings is shown in , with 0
corresponding to setting the switch to the right, a 1
corresponding to setting the switch to the left, and “don’t care”
represented as an “X.”
Table 2. PLL Settings
PLL
Mode
PLL-CTRL0
SW1-1
PLL-CTRL1
SW1-2
PLL-CTRL2
SW1-3
64×f
s
0 0 0
256×f
s
0 1 0
384×f
s
X X 1
512×f
s
1 0 0
Bypass 1 1 0
The ADR-SEL switch (SW1-4) determines the SPI address of
the AD1940. The default is 0 (switch to the right).
INPUT ROUTING
Audio data is routed to the AD1940 via four jumpers: J4, J5, J6,
and J7. A description of these jumpers is in Table 3.
Table 3. SDATA_INx Routing
Component Function
J4 Select data to input to AD1940 – SDATA_IN0
J5 Select data to input to AD1940 – SDATA_IN1
J6 Select data to input to AD1940 – SDATA_IN2
J7 Select data to input to AD1940 – SDATA_IN3
Input clocks are configured via two jumpers: J8 and J9. A
description of these jumpers is in Table 4.
Table 4. LRCLK_IN/BCLK_IN Routing
Component Function
J8
Select frame clock source for AD1940 serial
input ports
J9
Select bit clock source for AD1940 serial input
ports
The AD1940 serial input ports are always configured as slaves,
so clocks must always be supplied from another source in order
for them to function.
ANALOG AUDIO INPUTS
The EVAL-AD1940AZ has three stereo 1/8’ input jacks,
allowing for a total of 6 channels of analog audio input. Input
channels 0-3 are routed to the AD1939 ADCs and input
channels 4-5 are routed to the AD1974 ADCs. In order to input
the converted audio data to the AD1940 DSP, it must be routed
appropriately using the audio data routing jumpers.
Proper configuration for inputting all analog audio to the DSP
is shown in Figure 8. Note that it is not necessary to use all
analog audio inputs simultaneously, and the jumpers can be set
in any desired configuration to allow for flexibility in routing a
combination of analog, digital, and S/PDIF inputs.
J4 J5 J6 J
7
SDATA_IN0 SDATA_IN1 SDATA_IN2 SDATA_IN3
1939_ DATA1 1939_DATA2 1974_ DATA1 DON’TCARE
Figure 8. Input Routing Jumpers - Analog Configuration
In an analog input configuration the AD1939 will most
commonly be used as the source for LRCLK and BCLK signals.
To route this signals to the AD1940’s LRCLK_IN and BCLK_IN
pins, configure the jumpers J8 and J9 as shown in Figure 9.
J9J8
BCLK_INLRCLK_IN
1939_BCLK1939_L RCLK
Figure 9. LRCLK_IN/BCLK_IN Routing Jumpers - Analog Configuration
With the jumpers configured as shown in Figure 8 and Figure 9,
the analog input signals will appear in SigmaStudio as input
channels 0-5, as shown in Figure 10.
ANALOGINPUT0
ANALOGINPUT1
ANALOGINPUT2
ANALOGINPUT3
ANALOGINPUT4
ANALOGINPUT5
Figure 10. Analog Inputs in SigmaStudio