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AS1545

Data Sheet - Te r m i n o l o g y

8 Terminology

Acquisition Time

The Acquisition time is the time needed by the ADC to accurately acquire the analog input voltage in the internal

sampling capacitor. During this time the ADC is in track mode.

Conversion Time

The Conversion Time is the time that the ADC needs to convert an acquired analog input into a corresponding digital

code. A Successive Approximation Register ADC usually needs a number of clocks dependant on the resolution.

During this time the ADC is in hold mode.

Throughput / Sample Rate

The Throughput or Sample Rate is the number of conversions performed by an ADC per second. It is usually specified

in Samples Per Second (SPS). The Throughput or Sample Rate is the reciprocal of the sum of Acquisition Time and

Conversion Time.

Aperture Delay

The Aperture Delay defines the time between the falling edge of CSN and the actual Sampling Instant. The Aperture

Delay Matching defines the maximum deviation of Aperture Delays across all 6 channels of one ADC.

Aperture Jitter

The Aperture Jitter is the deviation of the actual Sampling Instant. This deviation is totally random and the standard

deviation of the distribution is calculated with one sigma.

Differential Nonlinearity (DNL)

The Differential Nonlinearity is the deviation between the actual code widths to the ideal code widths of 1 LSB,

comparing all contiguous codes in the ADC. The ADC is specified according to its maximum and minimum DNL values

across all codes. A DNL value equal to -1 indicates a missing code in the transfer function.

Integral Nonlinearity (INL)

The Integral Nonlinearity measures the deviation from the actual transfer function to the best straight line that

minimizes the INL worst case values.

Offset Error

The Offset Error defines the absolute deviation of the first code transition (0x000h) to (0x001h) from the ideal input

voltage (AGND + 0.5 LSB) in Single Ended and Pseudo Differential Mode (binary output coding).

Offset Error =

Offset Error Match

Ended and Pseudo Differential Mode (binary output coding).

Gain Error

The Gain Error defines the absolute deviation of the last code transition (0xFFEh) to (0xFFFh) from the ideal input

Gain Error =

Gain Error Match

and Pseudo Differential Mode (binary output coding).

VIN

VREF

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4096

×

AVG MeasuredCodes

()

–

OffsetError

AVG MeasuredCodes

()

VIN

VREF

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4096

×

–

–