ADS5484_2 Datasheet, PDF (22/37 Pages) Texas Instruments – 16-Bit, 170/200-MSPS Analog-to-Digital Converters

ADS5484
ADS5485
SLAS610C – AUGUST 2008 – REVISED OCTOBER 2009 ............................................................................................................................................... www.ti.com
Clock Inputs
The ADS548x equivalent clock input circuit is shown in Figure 37. The clock inputs can be driven with either a
differential clock signal or a single-ended clock input, but differential is highly recommended. The characterization
of the ADS548x is typically performed with a 3-V_PP differential clock, but the ADC performs well with a differential
clock amplitude down to ~1 V_PP, as shown in Figure 39 and Figure 40 . The performance is optimized when the
clock amplitude is kept above 2 V_PP. The clock amplitude becomes more of a factor in performance as the
analog input frequency increases. When single-ended clocking is a necessity, it is best to connect CLKM to
ground with a 0.01-μF capacitor, while CLKP is ac-coupled with a 0.01-μF capacitor to the clock source, as
shown in Figure 38.
Figure 37. Clock Input Circuit
Square Wave or
Sine Wave
0.01 mF
CLKP
ADS548x
CLKM
0.01 mF
S0168-08
Figure 38. Single-Ended Clock
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