STPM01 datasheet(42/56 Pages) STMICROELECTRONICS

42 / 56 page

Theory of operation

STPM01

42/56

For permanent set of the TSTD bit, which will cause no more writing to the Configuration

bits, the procedure above must be conducted in such way that steps 6 to 13 are performed

in series during single period of active SCS because the idle state of SCS would make the

signal TSTD immediately effective which in turn, would abort the procedure and possibly

destroy the device due to clearing of system signal RD and so, connecting all gates of 3V

NMOS sense amplifiers of already permanently set CFG bits to the VOTP source.

8.24

Energy calculation algorithm

Inside the STPM01 the computing section of the measured active power uses a completely

new signal patented process approach. This approach allows the device to reach high

performances in terms of accuracy.

The signals, coming from the sensors, for the instantaneous voltage:

v(t) = V•sin

ωt; where V is the peak voltage and ωis related to the line frequency (see[1])

and the instantaneous current:

i(t) = I • sin (

ωt + ϕ); where I is the peak current, ωis related to the line frequency and ϕ is the

phase difference between voltage and current (see[2]).

STPM01 数据表(PDF) 42 Page - STMicroelectronics