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SDA

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REPEATED

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ADC101C021, ADC101C027

SNAS446D – FEBRUARY 2008 – REVISED FEBRUARY 2013

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Timing Diagrams

Figure 1. Serial Timing Diagram

Specification Definitions

ACQUISITION TIME is the time required for the ADC to acquire the input voltage. During this time, the hold

capacitor is charged by the input voltage.

APERTURE DELAY is the time between the start of a conversion and the time when the input signal is internally

acquired or held for conversion.

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.

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.

LSB), after adjusting for offset error.

INTEGRAL NON-LINEARITY (INL) is a measure of the deviation of each individual code from a line drawn from

negative full scale (½ LSB below the first code transition) through positive full scale (½ LSB above the last code

transition). The deviation of any given code from this straight line is measured from the center of that code value.

INTERMODULATION DISTORTION (IMD) is the creation of additional spectral components as a result of two

sinusoidal frequencies being applied to an individual ADC input at the same time. It is defined as the ratio of the

power in both the second and third order intermodulation products to the power in one of the original frequencies.

MISSING CODES are those output codes that will never appear at the ADC output. The ADC101C021 is

guaranteed not to have any missing codes.

OFFSET ERROR is the deviation of the first code transition (000...000) to (000...001) from the ideal (i.e. GND +

0.5 LSB).

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 components below half the clock frequency, including

harmonics but excluding d.c.

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