SLAAED9 November 2023 TAA5412-Q1 , TAC5311-Q1 , TAC5312-Q1 , TAC5411-Q1 , TAC5412-Q1
When diagnostics are enabled, the fault diagnostic signal chain is constantly scanning the input channels. This multiplexing occurs automatically, but the rate at which the channels are scanned can be adjusted in DIAG_CFG4. The repetition rate can be set to 1 ms, 4 ms, 8 ms, or set to continuously scan as fast as possible. The default scan rate is 4 ms. The scan rate is the time between the end of one scan cycle and the beginning of the next. Since the sample rate of the diagnostic ADC is typically much faster than the scan rate, the scan rate is effectively the time between fault readings. Using the continuous back-to-back scan mode is recommended for the fastest response time and greatest signal integrity for the record channel. This selection causes the diagnostic ADC to sample at the same rate as the audio ADC and eliminates the small amount of coupling distortion that can arise from discontinuities in the diagnostic sampling. The power consumption of the diagnostic signal chain scales with the scan repetition rate. In back-to-back continuous scanning, the AVDD current can be expected to increase by approximately 2.5 mA compared to the 4-ms scan rate setting. For this reason, continuously scanning in power-sensitive applications is not recommended unless a system is particularly prone to faults and fast response time is needed.