Can the DAC in the LB563 directly drive headphones? Are there any compatible or recommended headphone amplifier chips?
It cannot directly drive ordinary passive headphones, especially the common 16 Ω/32 Ω ones.
The LB563’s on-chip Audio DAC mainly provides analog audio signals and has limited current capability to drive low-impedance loads. Direct connection may not achieve the expected results, and issues such as low volume and high distortion may occur.
In the SDK, the eh-lb563 board also adds an AW8155 analog power amplifier after the on-chip Audio Codec. See the configuration in board.conf (SiFli-SDK/customer/boards/eh-lb563/hcpu/board.conf:28) and PA Kconfig (SiFli-SDK/customer/peripherals/pa/Kconfig:14).
However, the AW8155 is mainly used for speakers and is not suitable as a headphone amplifier. If connecting active headphones, an external amplifier, or a high-impedance line-in, the DAC can be directly used as a signal source, but DC blocking, biasing, and filtering still need to be handled according to the chip’s reference design.