SLVSF02D March 2019 – May 2020 TPS23881
The TPS23881 features 10 multi-slope integrating converters. Each of the first eight converters is dedicated to current measurement for one channel and operate independently to perform measurements during classification and when the channel is powered on. When the channel is powered, the converter is used for current (100-ms averaged) monitoring, power policing, and DC disconnect. Each of the last two converters are shared within a group of four channels for discovery (16.6-ms averaged), port powered voltage monitoring, power-good status, and FET short detection. These converters are also used for general-purpose measurements including input voltage (1 ms) and die temperature.
The ADC type used in the TPS23881 differs from other similar types of converters in that the ADCs continuously convert while the input signal is sampled by the integrator, providing inherent filtering over the conversion period. The typical conversion time of the current converters is 800 µs, while the conversion time is 1 ms for the other converters. Powered-device detection is performed by averaging 16 consecutive samples which provides significant rejection of noise at 50-Hz or 60-Hz line frequency. While a port is powered, digital averaging provides a channel current measurement integrated over a 100-ms time period. Note that an anti-aliasing filter is present for powered current monitoring.
During powered mode, current conversions are performed continuously. Also, in powered mode, the tSTART timer must expire before any current or voltage ADC conversion can begin.