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PMM Discovery 1

TPS23841

SLUS745A – NOVEMBER 2006 – REVISED MAY 2007

POWER MANAGEMENT MODE FUNCTIONAL DESCRIPTION (continued)

PMM Discovery 1 function waveforms for the N and CINT pins are shown in Figure 10 . The measurement is

being performed using 25 k Ω impedance between the P and N pin. The Discovery 1 voltage is allowed to settle

for approximately 5ms before the A/D begins integrating. The voltage on the CINT pin shows the A/D cycle.

There are four distinct regions to any A/D cycle: pre-charge (to a known starting voltage), charge, coarse

discharge, and fine discharge. CINT pin is very high impedance therefore extreme care must be taken to avoid

any noise or leakage affecting this pin. For the measurements where CINT voltage is shown a buffer was used

to prevent performance degradation. The A/D measurement time is approximately 18ms. The entire Discovery 1

function takes approximately 22 ms to complete. At the end of the A/D cycle the Discovery 1 current is stored in

the Discovery Current Register and the function done bit is set. The applied Discovery 1 voltage level remains

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 10.

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