LTC2204 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC2204' PDF : 36 Pages View PDF
LTC2205/LTC2204
APPLICATIONS INFORMATION
Output Clock
The ADC has a delayed version of the encode input available
as a digital output. Both a noninverted version, CLKOUT+
and an inverted version CLKOUT– are provided. The
CLKOUT+/CLKOUT– can be used to synchronize the
converter data to the digital system. This is necessary
when using a sinusoidal encode. Data can be latched
on the rising edge of CLKOUT+ or the falling edge of
CLKOUT–. CLKOUT+ falls and CLKOUT– rises as the data
outputs are updated.
Digital Output Randomizer
Interference from the ADC digital outputs is sometimes
unavoidable. Interference from the digital outputs may be
from capacitive or inductive coupling or coupling through
the ground plane. Even a tiny coupling factor can result in
discernible unwanted tones in the ADC output spectrum.
By randomizing the digital output before it is transmitted
off chip, these unwanted tones can be randomized, trading
a slight increase in the noise floor for a large reduction in
unwanted tone amplitude.
The digital output is “Randomized” by applying an
exclusive-OR logic operation between the LSB and all
other data output bits. To decode, the reverse operation
is applied; that is, an exclusive-OR operation is applied
between the LSB and all other bits. The LSB, OF and
CLKOUT output are not affected. The output Randomizer
function is active when the RAND pin is high.
LTC2205/LTC2204
CLKOUT
CLKOUT
OF
OF
D15
D15/D0
D14
D14/D0
•
•
D2
•
D2/D0
D1
D1/D0
RAND = HIGH,
SCRAMBLE
ENABLED
RAND
D0
D0
22054 F12
Figure 12. Functional Equivalent of Digital Output Randomizer
22054fc
27
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