Datasheet
Theory of operation STPMC1
54/77 Doc ID 15728 Rev 7
U
Xmax
= 2
12
I
Xmax
= 2
16
There is no differences between status register of x phase in DAx, DRx, DFx, except for first
bit of status register [0]
BIL
. This bit indicates no-load condition.
In DAx status register bit
BIL
is represents NLC for phase X active energy.
In DRx status register bit
BIL
is represents NLC for phase X reactive energy.
In DFx status register bit
BIL
is represents NLC for phase X fundamental energy.
In standalone operating mode the 3-ph
BIL
signal is available on SCLNLC pin, 3-ph SIGN in
the SYN pin and Tamper flag (is the OR of all tamper conditions - see paragraph
9.10
) in
SDATD pin. All the other signals can be read only through SPI interface.
When STPMC1 is used in peripheral mode all these signals can be read through the SPI
interface. See paragraph
9.18
for details on the Status bit location in the STPMC1 data
records.
9.19 Configuration bits map
As indicated in the data records map (see paragraph
9.17
), the STPMC1 has 112
configuration bits (CFG data records). Each of them consists of paired elements, one is the
latch (the OTP shadow), and the other is the OTP antifuse element. In this way all the
configuration bits that control the operation of the device can be written in a temporary or
permanent way.
In case of temporary writing the configuration bits values are written in the so-called shadow
registers, which are simple latches that hold the configuration data. The shadow registers
are cleared whenever a reset condition occurs (both POR and remote reset).
In case of permanent writing the configuration bits are stored in the OTP (one time
programmable) cells that keep the information permanently even if the STPMC1 is without
supply, but, once written, they cannot be changed anymore. That's why the CFG are used to
keep critical informations like configuration and calibration values of device. When the
STPMC1 is released all antifuses presents low logic state.
Table 32. X-phase status bits description
Bit Name 0 1
0
BIL
No-load Condition not detected No-load condition detected
1
BCF
ΣΔ signals alive One or both ΣΔ signal stuck
2
BFR
Frequency of phase voltage is in range
Frequency of line voltage is out of range or voltage
amplitude is below threshold (
LOW
= 1)
3 SIGN Active energy is negative Active energy is positive
4
LIN
Phase 0 ≤ u < π Phase π ≤ u < 2π
5 ZRC After zero crossing After max value crossing
6
LOW
U
x
> U
Xmax
/ 16 U
x
< U
Xmax
/ 32
7
NAH
Single Wire Meter mode
I
X
> I
Xmax
/4096 and
BFR
==1
Normal operation mode
BFR
==0 or I
X
< I
Xmax
/ 8192 and
BFR
==1