Datasheet

2
f1
2
Fn
2
f2
10
x
A
A++A
logTHD = 20
/
ADC121C021, ADC121C021Q, ADC121C027
www.ti.com SNAS415F –JANUARY 2008–REVISED MARCH 2013
TOTAL HARMONIC DISTORTION (THD) is the ratio, expressed in dBc, of the rms total of the first n harmonic
components at the output to the rms level of the input signal frequency as seen at the output. THD is calculated
as
(1)
where A
f1
is the RMS power of the input frequency at the output and A
f2
through A
fn
are the RMS power in the
first n harmonic frequencies.
THROUGHPUT TIME is the minimum time required between the start of two successive conversions. It is the
acquisition time plus the conversion time.
LEAST SIGNIFICANT BIT (LSB) is the bit that has the smallest value or weight of all bits in a word. This value is
LSB = V
A
/ 2
n
(2)
where V
A
is the supply voltage for this product, and "n" is the resolution in bits, which is 12 for the ADC121C021.
MOST SIGNIFICANT BIT (MSB) is the bit that has the largest value or weight of all bits in a word. Its value is
1/2 of V
A
.
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