ZHCSFY3B November 2016 – February 2019 TAS2559
PRODUCTION DATA.
The TAS2559 monitors the battery voltage and audio signal to automatically decrease gain when the battery voltage is low and audio output power is high. This provides louder audio while preventing early shutdown at end-of-charge battery voltage levels. The battery tracking AGC starts to attenuate the signal once the voltage at the Class-D output exceeds VLIM for a given battery voltage (VBAT). If the Class-D output voltage is below the VLIM value, no attenuation occurs. If the Class-D output exceeds the VLIM value the AGC starts to attack the signal and reduce the gain until the output is reduced to VLIM. Once the signal returns below VLIM plus some hysteresis the gain reduction decays. The VLIM is constant above the user configurable inflection point. Below the inflection point the VLIM is reduced by a user configurable slope in relation to the battery voltage. The attack time, decay time, inflection point and VLIM/VBAT slope below the inflection point are user configurable. The parameters for the battery tracking AGC are part of the DSP core and can be set using the PurePath Console 3 Software TAS2559 Application software for the TAS2559 part under the Device Control Tab. Below a VBAT level of 2.9 V, the boost will turn on to ensure correct operation but results in increased current consumption. The device is functional until the set brownout level is reached and the device shuts down. The minimum brownout voltage is 2.7 V.