Z8F2480 Datasheet, PDF (21/24 Pages) Zilog, Inc. – Load current up to 3 amps

Z8F2480 Power Monitor with an eZ80F91 Webserver
Reference Design
Figure 9. Current Measurement Error vs. Load Current
Summary
When calibrated, this Z8F2480 Power Monitor with an eZ80F91 Webserver reference
design is able to measure line voltages and load currents over an entire input range with an
error rate of less than 2%.
The accuracy of the phase shift measurement in this reference design was not analyzed;
however, when using purely resistive loads (i.e., current and voltage in-phase), the web
page typically shows a power factor close to 1, as expected, suggesting that at least for
resistive loads, the system is reasonably accurate.
Although no attempt was made to calibrate the displayed line frequency, the Z8F2480
Power Monitor software does perform a self-calibration of its Internal Precision Oscillator
(IPO) just after startup that improves the accuracy of the line frequency measurement dis-
played on the web page. When used with 60 Hz systems, the displayed frequency contains
less than 2% error. It is expected that the displayed frequency will also be within 2% of the
AC line frequency for 50 Hz systems.
RD002702-0814
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