SLOSE86B july 2022 – july 2023 TAS2781
PRODUCTION DATA
The TAS2781 is a mechanism used in connection with the Y Bridge confiuration of the output stage of Class-D. It is based on monitoring the absolute value of the audio stream and selecting the proper supply, PVDDH or PVDDL.
When the signal is initially above the programmed LVS threshold the Class-D is supplied by PVDDH rail. If the signal level drops below this threshold for longer than the hysteresis time defined by LVS_HYS[3:0] register bits, the Class-D supply will switch to PVDDL. If the signal goes back to the initial level the Class-D supply will switch back to PVDDH.
By default he LVS threshold is configured to be a value relative to the PVDDL voltage (LVS_DET = 1). Use the LVS_RTH[3:0] register bits for setting the threshold (default = 0.7 V).
Setting bit LVS_DET bit to low forces the LVS threshold to a fixed value defined by the LVS_FTH[4:0] register bits.
LVS threshold is refered relative to the output signal level and it is measured in dBFS.
In an use case when CDS_MODE[1:0]=11 (PWR_MODE2 from Section 11.1), the fixed LVS threshold can be set using register bits LVS_TH_LOW[1:0].