Cirrus Logic CDB4207 - Manual (Page 3)

CDB4207
DS880DB1 3
1. HARDWARE SYSTEM OVERVIEW
The CDB4207 allows for easy and complete evaluation of the CS4207 HD Audio CODEC. Use of the CDB4207 re-
quires only a PC with an available HD Audio Bus header. If desired the CDB4207 can be powered solely from the
connected PC. The CDB4207 supports microphone and line-level analog input signals, line-level and headphone
analog output signals, digital microphone input signals, and optical S/PDIF input and output signals.
1.1 CS4207
A description of the CS4207 HD Audio CODEC is included in the CS4207 datasheet. See Figure 2 on page
11 for the CS4207 circuit schematic.
1.2 Analog Inputs
The analog input circuitry on the CDB4207 allows for all possible input configurations of the CS4207 to be
tested. Microphone and line-level inputs are connected to the CS4207 using standard 1/8” (3.5 mm) or 1/4”
(6.35 mm) jacks. All input configurations are passive and use the recommended DC-blocking capacitors
and anti-aliasing filter capacitors.
The CDB4207 supports the following microphone input types: stereo fully-differential signals (J50 and J56),
stereo single-ended/pseudo-differential signals (J42), and mono single-ended/pseudo-differential signals
with phantom power (J28, into left channel of CS4207). Jumpers J46 and J52 connect the inverting micro-
phone input pins of the CS4207 to either the negative signals of the differential input jacks or ground (for
single-ended/pseudo-differential input types). Jumpers J33 and J37 configure the microphone input anti-
aliasing capacitor for common-mode or differential filtering. Optionally, an external load may be applied to
the MICBIAS pin of the CS4207 using J27. Current sensing for the MICBIAS supply is accomplished by un-
shunting J36 and measuring the voltage across R33. The CDB4207 supports stereo single-ended/pseudo-
differential line-level input signals (J68).
The sleeve connection of the MIC and line input jacks is used for their respective signal’s return path. The
sleeve should thus be connected to the negative inputs of the CS4207’s MIC and/or line input pins when
configured in pseudo-differential mode. J43 and J60 are provided to connect the sleeve to board ground.
The jumpers should be shunted when the MIC and/or line input source is floating and must use the board
ground for its ground reference. To avoid ground loop issues, the jumpers should not be shunted if the MIC
and/or line input source has its own external ground reference.
The microphone input jack presence detect signal is triggered by inserting a plug into either J42 or J28 or
shunting J40. The line-level input jack presence detect signal is triggered by inserting a plug into J68 or
shunting J61.
See Figure 3 on page 12 for the analog input circuit schematic and Section 3 on page 7 for the analog input
connections and jumper selections. There is no on-board signal attenuation; see CS4207 datasheet for full-
scale input amplitudes.
1.3 Analog Outputs
The analog output circuitry on the CDB4207 allows for full evaluation of the CS4207’s analog outputs. Head-
phone and line-level outputs are connected to the CS4207 using standard 1/8” (3.5 mm) or 1/4” (6.35 mm)
jacks. All output paths are passive. The headphone outputs use the recommended anti-peaking filters. The
line-level outputs use the recommended DC-blocking capacitors (single-ended only) and low pass filters.
The headphone outputs are stereo single-ended/pseudo-differential signals available at J48. Optionally, a
test load of 32
Ω or 16 Ω can be connected to each channel by using J47. The line-level outputs can be
configured as stereo single-ended or fully-differential signals. For lineout 1, the single-ended or full-differ-
ential output option is selected using J59 and J51. The stereo single-ended output is available at J70. The