CS5334 CS5335
3. running the high pass filter with a fast settling
time constant,
4. freezing the dc offset register, and
5. reconnecting the internal ADC inputs to the
input pins.
This procedure takes 4,160 cycles of LRCK.
Unlike the system calibration procedure de-
scribed in the High Pass Filter section, a dc
calibration performed during start-up will only
eliminate offsets internal to the CS5334/5, and
should result in output codes which accurately
reflect the differential dc signal at the pins.
Power-Down
The CS5334 and CS5335 have a power-down
mode wherein typical consumption drops to 1.0
mW. This is initiated when a loss of clock is de-
tected (either LRCK or MCLK in Slave Mode or
MCLK in Master Mode), RST is enabled or
DIF0 / DIF1 are at a logic 1. The initialization
sequence will begin whenever valid clocks are
restored, RST is disabled and DIF0 / DIF1 are
restored. If the MCLK / LRCK frequency ratio
changes during power-down, the CS5334/5 will
adapt to these new operating conditions. How-
ever, only the RST method of power-down will
include the Master/Slave decision in the initiali-
zation sequence.
Grounding and Power Supply Decoupling
As with any high resolution converter, the
CS5334 and CS5335 require careful attention to
power supply and grounding arrangements to op-
timize performance. Figure 1 shows the
recommended power arrangements with VA+
connected to a clean +5 volt supply. VD+ should
be derived from VA+ through a 2 ohm resistor.
VD+ should not be used to power additional
digital circuitry. All mode pins which require
VD+ should be connected to pin 6 of the
CS5334/5. All mode pins which require DGND
should be connected to pin 5 of the CS5334/5.
AGND and DGND, Pins 4 and 5, should be con-
nected together at the CS5334/5. DGND for the
CS5334/5 should not be confused with the
ground for the digital section of the system. The
CS5334/5 should be positioned over the analog
ground plane near the digital / analog ground
plane split. The analog and digital ground planes
must be connected elsewhere in the system. The
CS5334/5 evaluation board, CDB5334/5, demon-
strates this layout technique. This technique
minimizes digital noise and insures proper power
supply matching and sequencing. Decoupling ca-
pacitors should be located as near to the
CS5334/5 as possible.
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DS237PP2