CS4218 datasheet(36/44 Pages) CIRRUS

36 / 44 page

PARAMETER DEFINITIONS

Resolution

The number of bits in the input words to the DACs, and in the output words from the ADCs.

Differential Nonlinearity

The worst case deviation from the ideal codewidth. Units in LSB.

Total Dynamic Range

TDR is the ratio of the rms value of a full scale signal to the lowest obtainable noise floor. It is

measured by comparing a full scale signal to the lowest noise floor possible in the codec (i.e.

attenuation bits for the DACs at full attenuation). Units in dB.

Instantaneous Dynamic Range

IDR is the ratio of a full-scale rms signal to the rms noise available at any instant in time,

without changing the input gain or output attenuation settings. It is measured using S/(N+D)

with a 1 kHz, -60 dB input signal, with 60 dB added to compensate for the small input signal.

Use of a small input signal reduces the harmonic distortion components to insignificance when

compared to the noise. Units in dB.

Total Harmonic Distortion

THD is the ratio of the rms value of a signal’s first five harmonic components to the rms value

of the signals fundamental component. THD is calculated using an input signal which is 3dB

below typical full-scale, and is referenced to typical full-scale.

Interchannel Isolation

The amount of 1 kHz signal present on the output of the grounded input channel, with 1 kHz

0 dB signal present on the other channel. Units in dB.

Interchannel Gain Mismatch

For the ADCs, the difference in input voltage that generates the full scale code for each

channel. For the DACs, the difference in output voltages for each channel with a full scale

digital input. Units in dB.

Frequency Response

Worst case variation in output signal level versus frequency over the passband. Tested over the

frequency band of 10 Hz to 20 kHz, with the sample frequency of 48 kHz. Units in dB.

Step Size

Typical delta between two adjacent gain or attenuation values. Units in dB.

Absolute Gain/Attenuation Step Error

The deviation of a gain or attenuation step from a straight line passing through the

no-gain/attenuation value and the full-gain/attenuation value (i.e. end points). Units in dB.

Offset Error

For the ADCs, the deviation of the output code from the mid-scale with the selected input at

REFBUF. For the DACs, the deviation of the output from REFBUF with mid-scale input code.

Units in LSB’s for the ADCs and volts for the DACs.

CS4218

DS135F1

CS4218 Datasheet(PDF) 36 Page - Cirrus Logic