ADC121S625EVAL/NOPB National Semiconductor, ADC121S625EVAL/NOPB Datasheet - Page 7

• Manufacturer Part Number: ADC121S625EVAL/NOPB
• Description: BOARD EVALUATION FOR ADC121S625
• Manufacturer: National Semiconductor

Specifications of ADC121S625EVAL/NOPB

• Number Of Adc's: 1
• Number Of Bits: 12
• Sampling Rate (per Second): 200k
• Data Interface: Serial
• Inputs Per Adc: 1 Differential
• Input Range: ±VREF
• Power (typ) @ Conditions: 2.25mW @ 200kSPS
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Utilized Ic / Part: ADC121S625
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: ADC121S625EVAL

Specification Definitions
APERTURE DELAY is the time between the second falling
SCLK edge of a conversion and the time when the input
signal is acquired or held for conversion.
COMMON MODE REJECTION RATIO (CMRR) is a mea-
sure of how well in-phase signals common to both input pins
are rejected.
CONVERSION TIME is the time required, after the input
voltage is acquired, for the ADC to convert the input voltage
to a digital word.
DIFFERENTIAL NON-LINEARITY (DNL) is the measure of
the maximum deviation from the ideal step size of 1 LSB.
DUTY CYCLE is the ratio of the time that a repetitive digital
waveform is high to the total time of one period. The speci-
fication here refers to the SCLK.
EFFECTIVE NUMBER OF BITS (ENOB, or EFFECTIVE
BITS) is another method of specifying Signal-to-Noise and
Distortion or SINAD. ENOB is defined as (SINAD − 1.76) /
6.02 and says that the converter is equivalent to a perfect
ADC of this (ENOB) number of bits.
FULL POWER BANDWIDTH is a measure of the frequency
at which the reconstructed output fundamental drops 3 dB
below its low frequency value for a full scale input.
GAIN ERROR is the difference between Positive Full Scale
Error and Negative Full Scale Error.
INTEGRAL NON-LINEARITY (INL) is a measure of the
deviation of each individual code from a line drawn from
negative full scale (
through positive full scale (
transition). The deviation of any given code from this straight
line is measured from the center of that code value.
MISSING CODES are those output codes that will never
appear at the ADC outputs. The ADC121S625 is guaranteed
not to have any missing codes.
NEGATIVE FULL-SCALE ERROR is the difference be-
tween the differential input voltage at which the output code
transitions from negative full scale and the next code and
−V
OFFSET ERROR is the difference between the differential
input voltage at which the output code transitions from code
000h to 001h and 1/2 LSB.
REF
CMRR = 20 LOG (∆Common Input / ∆Output)
+ 0.5 LSB
1
⁄
2
LSB below the first code transition)
1
⁄
2
LSB above the last code
7
POSITIVE FULL-SCALE ERROR is the difference between
the differential input voltage at which the output code transi-
tions to positive full scale V
POWER SUPPLY REJECTION RATIO (PSRR) is a mea-
sure of how well a change in the supply voltage is rejected.
It is the ratio of the change in Full-Scale Gain Error or the
Offset Error that results from a change in the d.c. power
supply voltage, expressed in dB.
SIGNAL TO NOISE RATIO (SNR) is the ratio, expressed in
dB, of the rms value of the input signal to the rms value of the
sum of all other spectral components below one-half the
sampling frequency, not including harmonics or d.c.
SIGNAL TO NOISE PLUS DISTORTION (S/N+D or SINAD)
Is the ratio, expressed in dB, of the rms value of the input
signal to the rms value of all of the other spectral compo-
nents below half the clock frequency, including harmonics
but excluding d.c.
SPURIOUS FREE DYNAMIC RANGE (SFDR) is the differ-
ence, 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.
TOTAL HARMONIC DISTORTION (THD) is the ratio, ex-
pressed in dB, 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
output and A
harmonic frequencies.
THROUGHPUT TIME is the minimum time required between
the start of two successive conversion.
f1
is the RMS power of the input frequency at the
f2
PSRR = 20 LOG (∆V
PSRR = 20 LOG (∆V
through A
f10
REF
are the RMS power in the first 9
minus 1.5 LSB.
A
A
/ ∆Offset)
/ ∆Gain)
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