PAC1933T-ISLASHJQ. datasheet(24/62 Pages) MICROCHIP

24 / 62 page

PAC1932/3/4

DS20005850C-page 24

 2017-2018 Microchip Technology Inc.

4.9

Power and Energy

The Full-Scale Range for Power depends on the

external

sense

resistor

used,

shown

Equation 4-5

EQUATION 4-5:

POWER FSR

CALCULATION

The device implements Power measurements by

multiplying VBUS and the VSENSE to give a result

VPOWER. VPOWER values are used to calculate

Proportional Power as shown in Equation 4-6. The

Proportional Power is the fractional portion of Power

FSR measured in one sample. Bipolar mode is where

VBUS is bipolar mode, VBUS is bidirectional mode, or

both VBUS and VSENSE are bipolar/bidirectional.

EQUATION 4-6:

PROPORTIONAL POWER

CALCULATION

To calculate the actual power from the Proportional

Power, multiply by the Power FSR as shown in

Equation 4-7

. This Actual Power number is the power

measured in one sample.

EQUATION 4-7:

POWER CALCULATION

These VPOWER results are digitally accumulated on

chip, and stored in the VACCUM registers.

The energy calculation Equations 4-8 and 4-9 use a

different denominator term depending on unipolar or

bipolar mode. Bipolar mode for energy applies when

bipolar/bidirectional mode is used for VBUS and/or

VSENSE. Equation 4-8 shows how to realize this using

the Accumulator results, Accumulator count and the

accumulation period, T. In this equation, T must be

known from a system clock time stamp or other

accurate indicator of the total accumulation period.

EQUATION 4-8:

ENERGY CALCULATION

EQUATION 4-9:

ENERGY CALCULATION

Equation 4-9

shows how to calculate energy using the

accumulated power and the sampling rate, f

PowerFSR

100 mV R

SEN SE



 32V



Where:

RSENSE =External RSENSE resistor value

100 mV = Full-Scale VSENSE voltage input

32V = Full-Scale VBUS voltage input

3.2V

SEN SE



PROP

Vpower

Denominator

-----------------------------------

Where:

Denominator =

228 (unipolar mode)

227 (bipolar mode)

ac tual

PowerFSR

PROP



Energy

Vaccum



Denominator

-----------------------------------

PwrFSR



AccCount

--------------------------



Where:

Denominator = 228 (unipolar mode)

=227 (bipolar mode)

Energy

V accum



Denominator

-----------------------------------

PwrFSR



--------------------------



Where:

Denominator = 228 (unipolar mode)

=227 (bipolar mode)

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