Rainbow Electronics MAX98088 - Manual (Page 107)

Stereo Audio Codec
with FLEXSOUND Technology
MAX98088
107
Output Bypass Switches
The IC's includes two output bypass switches that solve
common applications problems. When a single trans-
ducer is used for the loudspeaker and receiver, the need
exists for two amplifiers to power the same transducer.
Bypass switches connect the IC's receiver amplifier
output to the speaker amplifier’s output, allowing either
amplifier to power the same transducer. In systems where
an external receiver amplifier is used, route its output to
the left speaker through RECP/RXINP and RECN/RXINN,
bypassing the Class D amplifier. In systems where an
external amplifier drives both the receiver and the IC's
line input, one of the differential signals can be discon-
nected from the receiver when not needed by passing it
through the analog switch that connects RECP/RXINP to
RECN/RXINN.
Figure 31. Output Bypass Switch Block Diagrams
Table 29. Output Bypass Switches Register
REGISTER BIT NAME DESCRIPTION
0x4A
7 INABYP
See the Microphone Inputs section.
4 MIC2BYP
1 RECBYP
RXINP to RXINN Bypass Switch
Shorts RXINP to RXINN allowing a signal to pass through the ICs. Disable the receiver
amplifier when RECBYP = 1.
0 = Disabled
1 = Enabled
0 SPKBYP
RXIN to SPKL Bypass Switch
Shorts RXINP/RXINN to SPKLP/SPKLN allowing either the internal or an external
receiver amplifier to power the left speaker. Disable the left speaker amplifier when
SPKBYP = 1.
0 = Disabled
1 = Enabled
EXTERNAL
RECEIVER
AMP
RECP/RXINP
SPLEN
POWER/DISTORTION
LIMITER
SPKBYP
10I*
10I*
RECN/RXINN
SPKLVDD
SPKLP
SPKLN
SPKLGND
+6dB
*OPTIONAL 10I RESISTORS IMPROVE DISTORTION
THROUGH THE ANALOG SWITCH.
SPEAKER AMPLIFIER BYPASS USING AN
EXTERNAL RECEIVER AMPLIFIER
RECBYP
RECREN
RECLEN
0dB
0dB
RECP/RXINP
SPLEN
POWER/DISTORTION
LIMITER
SPKBYP
RECN/RXINN
SPKLVDD
SPKLP
SPKLN
SPKLGND
+6dB
SPEAKER AMPLIFIER BYPASS USING THE
INTERNAL RECEIVER AMPLIFIER
RECBYP
RECREN
RECLEN
0dB
0dB
RECP/RXINP
SPLEN
POWER/DISTORTION
LIMITER
SPKBYP
RECN/RXINN
SPKLVDD
SPKLP
SPKLN
SPKLGND
+6dB
CONTROLLING AN EXTERNAL RECEIVE
AMPLIFIER AND SPEAKER
RECBYP
RECREN
RECLEN
0dB
0dB
EXTERNAL
RECEIVER
AMP