Cirrus Logic CDB35L00-X4 - Manual (Page 5)

DS913DB2 5
CDB35L00-X4
1.4.1 Shutdown Control Resistors
The CDB35L00-X4 contains 0 ohm resistors (R1-R4) which
allow the individual CS35L00 shutdown pins to be discon-
nected from the S1 switch or connected to an external con-
trol device. These resistors are located on the back side of
the CDB35L00-X4 board near S1, as shown highlighted in
blue in
Figure 2 .
R1-R4 are connected to SD on U1-U4, respectively. It is rec-
ommended that the individual shutdown line pull-up resistors
for U1-U4 (R10, R20, R30, R40) be left populated to help
prevent the individual SD control lines from floating.
Table 3. S1 Switch Default Shutdown Configurations
1.5 Gain Control
The amplifier gain of the CS35L00 can be configured to operate with either a +6 dB gain or a +12 dB gain
as shown in
Table 1 on page 3 . The amplifier gain is selectable through the GAIN setting on the S1 switch.
This is connected to the GAIN_SEL pins on the four CS35L00 devices as shown in Figure 4 on page 9 .
Note: The CS35L00 devices should be placed into shutdown via either the S1 switch or by removing pow-
er before changing the GAIN setting.
1.5.1 Optional Gain Adjustment Resistors
The CDB35L00-X4 contains optional gain adjustment resistor placeholders for each CS35L00 device
(R11, R12, R21, R22, R31, R32, R41, R42). By default these are not populated and the CS35L00 oper-
ates at its gain control setting as set by the S1 switch. See
Table 1 . The gain adjustment resistors are only
necessary when a gain of +6 dB or a gain of +12 dB is not desired. By adding series resistance to the
input, the signal amplitude to the CS35L00 will be reduced, and will reduce the overall system gain. The
typical input impedance values of the CS35L00 as well as how to calculate the resistor values for a de-
sired gain can be found in the device datasheet.
In order to use the optional gain adjustment resistors for U1, the traces between the R11 pads and the
traces between the R12 pads must be cut in order to break the bypass circuit before populating R11 and
R12 with the desired resistance values. The location of these required cuts are shown in
Figure 3 on page
6 . After the trace between the pads has been broken, the gain adjustment resistors can be added to the
board.
The gain adjustment resistors for U2, U3, and U4 can be added in the same manner as is described for
U1 (above).
SD1-2 SD3-4
LOW U1 & U2 OFF U3 & U4 OFF
HIGH U1 & U2 ON U3 & U4 ON
Figure 2. Shutdown Control Resistors