Datasheet

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PMM Discovery 2
PMM Classification
TPS23841
SLUS745A – NOVEMBER 2006 – REVISED MAY 2007
POWER MANAGEMENT MODE FUNCTIONAL DESCRIPTION (continued)
PMM Discovery 2 function waveforms for the N and CINT pins are shown in Figure 11 . Again the measurement
is being performed using 25 k Ω impedance between the P and N pin. The Discovery 2 function was called after
a Discovery 1 function so the voltage ramps from 4.4 V to 8.8 V below the P pin. The Discovery 2 voltage is
given 5 ms to settle before the A/D begins to integrate. At the end of the A/D cycle the Discovery 2 current is
stored in the Port Discovery Current Register and the function done bit is set. The applied Discovery 2 voltage
level will remain until a new function is called. The data for this measurement will remain stored in the Discovery
Current Register until another Discovery 1 or 2 function is called.
Figure 11.
PMM Classification function looks similar to Discovery 1 and 2 except that the voltage between the P and N pins
regulates to approximately 17.5 V. At the end of the A/D cycle the classification current is stored in the Port
Current Register and the done bit is set. The applied classification level will remain until a new function is called.
The data for this measurement remains stored in the Port Current Register until either the Classify or ISample
function is called.
As indicated in the flow diagram of Figure 1 , the TPS23841 in AM only performs classification at one port at a
time. Similarly, PMM applications should take care to ensure that only one port per device is put into the
classification mode at any one time to limit power dissipation in the package.
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