AN2299

Temperature calibration

Rev2

23/26

parameters. For this reason measured power will be proportional to the product of voltage

and current calibrators, that will be defined as a "power calibrator" Kp:

The minimum value of this new calibrator Kp is obtained with the minimum value of both

calibrators Kv and Ki, and its maximum value from the maximum value of Kv and Ki:

In this way a power correction parameter related to Kv and Ki has been deduced.

This parameter has a correction dynamic greater than Kv and Ki. This this means that

greater tolerances can be compensated, but in a single calibration point. In fact, with power

calibration linearity cannot be guaranteed if calibration is performed in a single point,

because power is calibrated, not voltage and current for which STPM01 has a great

linearity. To find out Kv and Ki that compensate power in a certain range, it could be useful

to perform the below procedure twice.

As done for Kv and Ki, to have the greatest correction dynamic, at the beginning of

calibration procedure, Kp should be put in the middle of this interval:

●

Calibrators‘ value

–

Kp = 0.78125

–Kv = Ki =

–

Ci = Cv = 137

and since LED pin frequency f is proportional to measured power P, it is possible to write an

equation analogous to Eq. 9 and Eq. 10 for the frequency:

calculated in Eq. 11.

b. Algorithm choice

This step is equivalent to that already explained for fast digital calibration procedure.

c. Offline parameters calculations

This step is equivalent to that already explained for fast digital calibration procedure.

d. Online Procedure

As done for fast digital calibration, before starting the online procedure it is necessary to

verify that the equipment is properly configured and connected.

PV

IKv

Ki

Kp

=

•

∝

•

∝

Eq. 35

Kv

Ki

Kp

==

Eq. 36

0.5625

Kv

MIN

Ki

MIN

•

Kv

MAX

Ki

MAX

•

1

=

<

=

Eq. 37

X

F

Kp

f

A

•

0.78125

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

=

Eq. 38