Instruction Manual

CDB5374
DS862DB1 17
The amplifier outputs are connected to external 680 Ω series resistors and 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.
2.2.3 Delta-Sigma Modulators
A CS5374 ∆Σ modulator performs the A/D function for a differential analog input signal from the amplifier.
The digital output is an oversampled ∆Σ bit streams.
2.2.3.1 Rough-Fine Inputs - INR, INF
The modulator analog inputs are separated into rough and fine signals, each of which has an anti-alias
RC filter to limit the signal bandwidth into the modulator inputs.
2.2.3.2 Offset Enable - OFST
The CS5374 ∆Σ modulator requires differential offset to be enabled to eliminate idle tones for a terminated
input. OFST is enabled by default in the CS5374 registers.
Analog Signals Description
INR1, INF1 Channel 1 analog rough / fine inputs
INR2, INF2 Channel 2 analog rough / fine inputs
VREF Voltage reference analog inputs
Digital Signals Description
MDATA[1..2] Modulator delta-sigma data outputs
MFLAG[1..2] Modulator over-range flag outputs
MCLK Modulator clock input
MSYNC Modulator synchronization input
PWDN[1..2] Power down mode enable (register bits)
OFST Internal offset enable (register bits)