STPM01 datasheet(27/56 Pages) STMICROELECTRONICS

27 / 56 page

STPM01

Theory of operation

27/56

The mono-flop limits the length of the pulses according to the LVS bit value.

The decoder distributes the pulses to MA and MB alternatively, which means that each of

them has only a half of selected frequency.

In case of detected negative power the behavior of MOP and MON depend on the ABS

configuration bit status. If this bit is set, the negative power is computed as it was positive

(absolute value regardless of the sign), and the MOP and MON signals maintain the pulse

sequence in order to keep the forward rotation direction of the motor. If ABS is zero negative

power is computed with its own sign, and the MOP and MON signals invert their logic state

in order to make the backward rotation direction of the motor. See the diagram below..

When a no-load condition is detected MOP and MON are held low.

8.16

Using STPM01 in microcontroller based meter (peripheral)

The higher flexibility of STPM01 allows its use in very high end microcontroller based energy

meters. In this case the STPM01 must be programmed to work in peripheral mode, all the

SPI pins (SCS, SCLNCL, SDATD, SYN) are used only for communication purposes allowing

the microcontroller to write and read the internal STPM01 registers. The peripheral mode

has two further different configuration modes according to the status of the APL

Figure 20.

Positive energy or absolute computation energy (ABS=1) stepper driving signals

MON

MOP

Figure 21.

Negative energy stepper driving signals

MON

MOP

STPM01 Datasheet(PDF) 27 Page - STMicroelectronics