Cirrus Logic CDB470xx - Manual (Page 67)

CDB47xxD Differential Schematic Descriptions
CDB47xxx User’s Manual
DS886DB11 Copyright 2014 Cirrus Logic, Inc 6-16
6.3 CDB47xxD Differential Schematic Descriptions
6.3.1 CDB47xxxD Block Diagram
Figure 6-13 shows the CDB47xxxD block diagram
6.3.2 Daughtercard Connectors
Figure 6-15 shows the schematic for the daughtercard connectors on the CDB47xxxD board.
See section Section 6.2.2 for description of circuitry.
6.3.3 Digital Audio and Control Connectors
Figure 6-16 shows the schematics for the digital audio and control connectors on the CDB47xxxD board.
See section Section 6.2.3 for description of circuitry.
6.3.4 Memory
Figure 6-17 shows the schematic for the Flash memory devices.
See section Section 6.2.4 for description of circuitry.
6.3.5 Microphone Preamplifier
Figure 6-18 shows the microphone preamplifier for the CDB47xxxD.
See section Section 6.2.5 for description of circuitry.
6.3.6 Power
Figure 6-19 shows the schematics for power on the CDB47xxxD board.
See section Section 6.2.6 for description of circuitry.
6.3.7 Input Filters
Figure 6-20 shows the input CDB47xxxD. Each channel of the CS470xx is differential and input has its
own input filter that consists of a current limiter, an AC-coupling capacitor (10
F), and an anti-aliasing
capacitor (2200 pF) which is not populated. The current limiter is scaled to make the CDB47xxxD capable
of accepting analog signals of up to 4V
RMS differentially.
6.3.8 Output Filters
Figure 6-21 shows the output filters for the CDB47xxxD.
Each channel of the CS470xx is differential and is fed to an op-amp that converts the differential signal
into a single-ended output with a maximum swing of 2 V
RMS
.
Each output has a series resistor (560
) to provide a voltage drop when the muting transistor is enabled,
and a mute transistor that will pull the output low when the mute control signal is enabled. The series
resistor is small enough that it does not affect the signal in normal operation, assuming a load of at least
5 k
 is connected to the analog output of the board.