SPMD150STP

Function description and application information

Doc ID 17160 Rev 1

11/23

4

Function description and application information

SPMD150STP can be seen divided in several main blocks (see Figure 1):

●

Power stage, to drive the motor windings

●

Logic interface, to interface the external signals to the internal circuitry

●

PWM current controller, to fix and control the current flowing in the motor phase

windings

●

Decay control block, to control the phase current decay mode

●

Phase sequence generator, to generate the motor phases driving sequence

●

Protection block, performing over current protectionand thermal shut-down to protect

the power bridges

4.1

Power stage

STMD150STP integrates two independent MOSFET full bridges, with intrinsic fast

freewheeling diodes. Switching patterns are generated by the phase sequence generator

and by the PWM current controller.

The power MOSFET cross conduction in one bridge leg, is avoided introducing a dead time

μs typical), between FETs switch off and the switch on.

VS (pin19) and GND2 (pin14) must be connected to the supply voltage, which can range

from 10 V to 42 V.

4.2

Logic interface

Logic interface connects the external logic signal to the proper internal blocks.

RESET (pin3), CLOCK (pin4), CW/CCW (pin5), CONTROL (pin9) and HALF/FULL (pin10)

have a 10k

Ω pull-up resistor to VSS (pin1), in order to prevent floating pins;

VSS can be connected to 3.3 V or 5 V, allowing the interface with the most popular

microcontroller. The internal structure is shown in Figure 8.

EN (pin8) has identical input structure, with the exception that the MOSFET drain of the

over-current and thermal protection is also connected to this pin (see Figure 9).

Due to this connection some care needs to be taken in driving this pin.

Inside the module a 100 k

Ω resistor and a 100 nF capacitor is provided, an open collector

driving is therefore the suggested solution.