E-L8150 STMICROELECTRONICS [STMicroelectronics], E-L8150 Datasheet - Page 29

• Manufacturer Part Number: E-L8150
• Description: Brushless motor predriver
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

L8150
When the SD signal has a falling edge the logic acquires the Hall codification and waits for
next Hall effect commutation, which is filtered using a filtering time of T
400µsec. The first significant zero-crossing signal is generated.
Also the second Hall effect commutation is filtered using T
zero-crossing signal is generated.
Starting form the second Hall effect commutation, after the acquisition of the filtered Hall
commutation, the logic outputs start applying the right pattern, and the motor is able to
accelerate again.
Next filtering time used for the Hall commutation is a fraction of the elapsed time between
the last two zero-crossing signals TDzc. This filtering time is used until the first rising edge
on signal HallU is detected and a new zero-crossing signal is generated.
●
Figure 20. Startup sequence forced by SD, supposing the motor rotating quickly in
This situation is similar to that described before, except DM behaviour. Let's suppose the SD
signal high, which means all phases in high impedance state. Since the signal SD is high
and considering that this is the reset signal for the whole logic part, the system is not able to
detect if the motor is rotating in the desired direction or not and by default the DM signal will
be high. So when the signal SD has a falling edge, the DM signal remains high, indicating
that the detected direction is equal to desired direction.
Only after the first filtered Hall effect commutation the system is able to determines if the
rotation direction is equal to the desired one. At this moment the DM signal becomes low.
Starting from the second Hall effect commutation, after the acquisition of the filtered Hall
commutation, the logic outputs starts applying the right pattern, and the motor starts to
decelerate.
Let's consider a startup sequence forced by SD, supposing the motor rotating quickly in
the direction not imposed by the FR signal:
SD
DM
ZC
HALL BUS
FILTER TIME
PHASES
the direction not imposed by the FR signal
MOTOR FREE RUN
400 us
T∆zc
400 us T∆zc/576
Precharge and hall effects filtering time description
PHASES EXCITED
MOTOR DECELERATING
T∆zc/576
PRECHARGE
MOTOR ACCELERATING
T∆zc/576
, after that the second
PRECHARGE
T∆zc/576
=
29/37