Datasheet
STPM01 Theory of operation
Doc ID 10853 Rev 8 33/60
The first 6 registers are read-only except for the 8 bit mode signals in the DFP register (the
mode signals will be described later in this paragraph). The last two registers CFL and CFH
can be also written because they contain the configuration bits. Among these last 64 bits (32
of CFL and 32 of CFH), 8 bits are used for parity nibbles, then only 56 bits are used for
configuring and programming the STPM01.
8.19 Configuration bits
All the configuration bits that control the operation of the device (CFL and CFH data records)
can be written in a temporary or permanent way. In case of temporary writing the
configuration bits value are written in the so called shadow registers which are simple
latches that hold the configuration data. In case of permanent writing the configuration bits
are stored in the OTP (one time programmable) cells that keep the information for an
undefined period of time even if the STPM01 is without supply, but, once written, they
cannot be changed anymore.
The shadow registers are cleared whenever a reset condition occurs (both POR and remote
reset).
As indicated in the data records table, the configuration bits are 56. Each of them consists of
paired elements, one is latch, the OTP shadow, and another is the OTP antifuse element.
When the STPM01 is released in the market, all antifuses represents logic low state but they
can be written by the user in order to configure the STPM01.This means that STPM01 can
retain 56 bits of information even if it has been unsupplied for an undefined time. That’s why
the CFG signals are used to keep certain configuration and calibration values of device.
Figure 23. STPM01 data records map
upper f(u)0 1
mode signals
p
p
iRMSuRMS
iMOM
uMOM
1bit
1bit 1bit
20 bit
20 bit 8 bit
6 bit
11 bit 16 bit
DAP
DRP
DSP
CFH
DFP
DEV
DMV
CFL
reactive energy
type0 active energy
apparent energy
type 1 energy
lower part of configurators
upper part of configurators
Status
lower f(u)
parity
parity
parity
parity
parity
parity
parity
parity
4 bit
msb lsb