SLASEM8A January 2019 – March 2019 TPA3255-Q1
PRODUCTION DATA.
As audio signals often have a peak to average ratio larger than one (average level below maximum peak output), the thermal performance for audio signals can be illustrated using burst signals with different burst ratios.
A burst signal is characterized by the high-level to low-level ratio as well as the duration of the high level and low level, e.g. a burst 1:4 stimuli is a single period of high level followed by 4 cycles of low level.
The following analysis of thermal performance for TPA3255-Q1 is made with the heatsink temperature controlled to 75°C.
The device is not thermally limited with 8-Ω load, but depending on the burst stimuli for operation at 75ºC heatsink temperature some thermal limitations may occur with a lower load impedance, depending on switching frequency and average to maximum power ratio. The figure below shows burst performance with a signal power ratio of 1:16 (low cycles power level 1/16 of the high cycles power level) and 1:8 .