When there are multiple audio inputs available such as a line-in and a wireless connection, a switch/multiplexer is needed to switch between audio sources. This same scheme can be used in systems where there are multiple speaker outputs and one source as well. A TMUX2889 can be used for all of these use cases, easily supporting line-in audio up to ±5.5V with a supply/battery voltage from 1.8～5.5V. Figure 8-1 shows the block diagram for these applications. Additionally, if IEC protection is needed on the external connectors (audio jack input or external speaker), 2 TPD1E10B06 can be used.

The TMUX2889 features excellent THD+N performance, so there is minimal impact to the audio signal quality through the switch. This allows the system designer to save a significant portion of board area without impacting signal integrity. Additionally, because of the low supply current requirement, the device's supply can be driven directly with a GPIO, allowing the user to put the device into a ultra-low power mode. In this mode the TMUX2889 operates with powered-off protection, so any high voltage present on the inputs will not propagate to the outputs. This helps keep correct power up cycling and increases system robustness.

Figure 8-1 Audio Headphone and Speaker Output Switching

Figure 8-2 Hearing Aid Telecoil MUX