Maxim-integrated 71M6533-DB Manual de usuario descargar pdf (Pagina 23)

71M6533-DB Demo Board User’s Manual

Page: 23 of 75 ` REV 3

1.9 CALIBRATION PARAMETERS

1.9.1 GENERAL CALIBRATION PROCEDURE

Any calibration method can be used with the 71M6533 chips. This Demo Board User’s Manual presents

calibration methods with three or five measurements as recommended methods, because they work with most

manual calibration systems based on counting "pulses" (emitted by LEDs on the meter).

Naturally, a meter in mass production will be equipped with special calibration code offering capabilities beyond

those of the Demo Code. It is basically possible to calibrate using voltage and current readings, with or without

pulses involved. For this purpose, the MPU Demo Code can be modified to display averaged voltage and

current values (as opposed to momentary values). Also, automated calibration equipment can communicate

with the Demo Boards via the serial interface and extract voltage and current readings. This is possible even

with the unmodified Demo Code.

Complete calibration procedures are given in section 2.2 of this manual.

Regardless of the calibration procedure used, parameters (calibration factors) will result that will have to be

applied to the 71M6533 chip in order to make the chip apply the modified gains and phase shifts necessary for

accurate operation. Table 1-2 shows the names of the calibration factors, their function, and their location in the

CE RAM.

Again, the command line interface can be used to store the calibration factors in their respective CE RAM

addresses. For example, the command

>]10=+16302

stores the decimal value 16302 in the CE RAM location controlling the gain of the current channel (CAL_IA) for

phase A.

The command

>]11=4005

stores the hexadecimal value 0x4005 (decimal 16389) in the CE RAM location controlling the gain of the

voltage channel for phase A (CAL_VA).

Constant

Address

(hex)

Description

CAL_VA

CAL_VB

CAL_VC

0x11

0x13

0x15

Adjusts the gain of the voltage channels. +16384 is the typical value. The

gain is directly proportional to the CAL parameter. Allowed range is 0 to

32767. If the gain is 1% slow, CAL should be increased by 1%.

CAL_IA

CAL_IB

CAL_IC

0x10

0x12

0x14

Adjusts the gain of the current channels. +16384 is the typical value. The

gain is directly proportional to the CAL parameter. Allowed range is 0 to

32767. If the gain is 1% slow, CAL should be increased by 1%.

PHADJ_A

PHADJ_B

PHADJ_C

0x18

0x19

0x1A

This constant controls the CT phase compensation. No compensation

occurs when PHADJ=0. As PHADJ is increased, more compensation is

introduced.

Table 1-2: CE RAM Locations for Calibration Constants

1 2 ... 18 19 20 21 22 23 24 25 26 27 28 ... 74 75

Comentarios a estos manuales

Sin comentarios

Maxim-integrated 71M6533-DB Manual de usuario Pagina 23

Comentarios a estos manuales

Relacionado con productos y manuales para Hardware Maxim-integrated 71M6533-DB