LTC2205 Linear Technology, LTC2205 Datasheet - Page 27

• Manufacturer Part Number: LTC2205
• Description: (LTC2204 / LTC2205) 65Msps/40Msps
• Manufacturer: Linear Technology

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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
CLKOUT
verter data to the digital system. This is necessary when
using a sinusoidal encode. Data can be latched on the
rising edge of CLKOUT
CLKOUT
are updated.
Digital Output Randomizer
Interference from the ADC digital outputs is sometimes
unavoidable. Interference from the digital outputs may be
+
+
/CLKOUT
falls and CLKOUT
–
can be used to synchronize the con-
+
or the falling edge of CLKOUT
–
RAND = HIGH,
Figure 12. Functional Equivalent of Digital Output Randomizer
rises as the data outputs
SCRAMBLE
ENABLED
–
are provided. The
RAND
D0
LTC2205/LTC2204
CLKOUT
D15
D14
OF
D2
D1
–
+
.
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 fl oor for a large reduction in
unwanted tone amplitude.
The digital output is “Randomized” by applying an exclu-
sive-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.
•
•
•
22054 F12
CLKOUT
OF
D15/D0
D14/D0
D2/D0
D1/D0
D0
LTC2205/LTC2204
27
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