SLUSC25A February 2015 – August 2017 TPS2388
PRODUCTION DATA.
To eliminate the possibility of false detection, the TPS2388 uses a TI proprietary 4-point detection method to determine the signature resistance of the PD device. False detection of a 25-kΩ signature can occur with 2-point detection type PSEs in noisy environments or if the load is highly capacitive.
Both detection 1 and detection 2 are merged into a single detection function which is repeated. Detection 1 applies I1 (160 μA) to a port, waits 60 ms, then measures the port voltage V1 with the integrating ADC. Detection 2 applies I2 (270 μA) to a port, waits 60 ms, then measures the port voltage V2. The process is repeated a second time. Multiple comparisons and calculations are performed on all four measurement point combinations to eliminate the effects of a non-linear or hysteretic PD signature. The resulting port signature is then sorted into the appropriate category.
NOTE
The detection resistance measurement result is also available in the Port Detect Resistance register.