Datasheet

2
f1
2
f6
2
f2
10
‡
A
A++A
logTHD = 20
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ADC78H90
SNAS227D –NOVEMBER 2003–REVISED MARCH 2013 www.ti.com
including harmonics but excluding d.c.
SPURIOUS FREE DYNAMIC RANGE (SFDR) is the difference, expressed in dB, between the rms values of the
input signal and the peak spurious signal where a spurious signal is any signal present in the output
spectrum that is not present at the input, excluding d.c.
TOTAL HARMONIC DISTORTION (THD) is the ratio, expressed in dB or dBc, of the rms total of the first five
harmonic components at the output to the rms level of the input signal frequency as seen at the output.
THD is calculated as
where
• A
f1
is the RMS power of the input frequency at the output
• A
f2
through A
f6
are the RMS power in the first 5 harmonic frequencies (1)
THROUGHPUT TIME is the minimum time required between the start of two successive conversion. It is the
acquisition time plus the conversion time. In the case of the ADC78H90, this is 16 SCLK periods.
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