STPM01 datasheet(28/56 Pages) STMICROELECTRONICS

28 / 56 page

Theory of operation

STPM01

28/56

configuration bit. The APL bit status changes the function of MOP, MON and LED pins

according to the description below.

APL=0:

In the MOP pin, the ZCR signal is available (see paragraph 3 for details about ZCR signal);

The pin MON provides the DOG signal. The DOG signal generates a 16ms long positive

pulse every 1.6 seconds. Generation of these pulses can be suspended if data are read in

intervals shorter than 1.6s. The DOG signal is actually a watchdog reset signal which can be

used to control an operation of an on-board microcontroller. It is set to high whenever the

VDDA voltage is below 2.5 V, but after VDDA goes above 2.5V this signal starts to run.

It is expected that an application microcontroller should access the data in the metering

device on regular basis at least 1/s (recommended is 32/s). Every latching of results in the

metering device requested from the microcontroller also resets the watchdog. If latching

requests does not follow each other within 1.6 second, an active high pulse on MON is

produced, because device assumes that microcontroller does not operate properly. An

application can use this signal either to control the RESET pin of its microcontroller or it can

be tied to some interrupt pin. The last possibility is recommended for a battery backup

application which can enter some sleep mode due to power down condition and should not

be reset by metering device because it would exit from the sleep mode.

The LED pin can be driven from AW wide Band (Active Energy as in standalone mode), AW

limited at fundamental, RW (Reactive Energy) or SW (Apparent Energy) according to the

value of KMOT bit.

In this case, since the LED pin is driven by signals different from AW, some other

relationship between the LSB of the register and must be defined:

KAWFund = 4*KAW [Wh]

KRW = 2*KAW [VARh]

KSW = KAW [VAh]

APL=1:

MOP provides the

∑∆ signal generated from the analog voltage input;

MON provides the

∑∆ signal generated from the analog current input, according to the

selection of the tamper module

LED provides the information about the selection of the current channel made by the tamper

module. If LED is low it means the primary channel is selected, if LED is high the secondary

channel is actually selected.

Table 14.

Led pin configuration in peripheral mode

KMOT (2 Bits)

Signal available in LED pin

# of Pulses

AW Type 0 (1)

P [kWh]

AW Type 1 (1)

P [kWh]

P [kVARh]

P [kVAh]

* Type0 is the Wide band Active Energy and Type1 is the fundamental Active Energy if FUND=0, if FUND=1 they are

swapped.

STPM01 数据表(PDF) 28 Page - STMicroelectronics

STPM01 数据表(HTML) 28 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56

数据表下载