CDB5378 Datasheet, PDF (18/72 Pages) Cirrus Logic – Single-channel Seismic Evaluation System

CDB5378
The CS3301/02 amplifier outputs include internal series resistors, so a differential anti-alias RC filter is
created by connecting 20 nF of high-linearity differential capacitance (2x 10 nF C0G) between each half
of the rough and fine signals. External 0-ohm resistors are included in series with the amplifier internal
anti-alias resistors to support testing of other anti-alias RC filter configurations.
INR+
INF+
INF-
INR-
INR+
INF+
INF-
INR-
Figure 2. Quad Group Routing of RC Filter Components
2.2.3 Delta-Sigma Modulator
The CS5373A ∆Σ modulator performs the A/D function for the differential analog signal from the
CS3301/02 amplifier. The digital output from the modulator is an oversampled ∆Σ bit stream.
Analog Signals
INR, INF
VREF
Description
Modulator analog rough / fine inputs
Voltage reference analog inputs
Digital Signals
MDATA
MFLAG
MCLK
MSYNC
Description
Modulator delta-sigma data output
Modulator over-range flag output
Clock input
Synchronization input
2.2.3.1 Rough-Fine Inputs - INR, INF
The modulator analog inputs are separated into rough and fine signals, each of which has a differential
anti-alias RC filter to limit the input signal bandwidth.
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DS639DB3