E-L8150 STMICROELECTRONICS [STMicroelectronics], E-L8150 Datasheet - Page 27

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

L8150
Figure 17. Startup sequence forced by FS comparator, supposing the motor rotating
When the signal coming from the FS comparator has a falling edge, by default a zero-
crossing signal is generated and the logic waits for a Hall effect commutation and applies to
it a filtering time of T
effect commutation happens before the filtering time is elapsed: this causes the reset of the
filter and, in consequence, a new count for the filter time of 400µsec. Until the motor is
rotating too quickly no Hall effect commutation is acquired by the logic, thus the logic outputs
force high impedance condition.
Only when the motor speed becomes lower than the speed necessary to obtain a
Tel/6>400µsec the Hall effect commutations are filtered and acquired.
If no Hall effect commutation is acquired during a period of TelMax/6, a precharge function
will be done.
Depending on the last filtered Hall effect codification present in the logic and, also, on the
Hall effect codification having a duration longer than 400µsec (because the Hall effect
codifications filtered have to be consecutive), the Hall effect commutations filtered using a
filter time of 400usec could be two or, more probably, three.
After this Hall effect commutations the logic outputs start applying the right pattern to the
motor windings.
The motor rotation direction is irrelevant, in fact this can influence only the kind of pattern
applied after the two or three filtered Hall effect commutation.
●
When the signal coming from the FS comparator has a falling edge, the logic waits for a Hall
effect commutation for a period of time equal to TelMAX/6. If no Hall effect commutation
happens during this time, the behaviour is the one described in the previous section, when a
startup sequence with motor stopped is described.
Let's suppose that during the counting period of TelMAX/6 a Hall effect commutation is
detected. This commutation is filtered using 400usec. Considering the hypothesis done,
starting from the Hall effect commutation detection, no more commutation will be detected
Let's consider a startup sequence forced by FS-Comparator, supposing the motor
rotating slowly.
FS
ZC
HALL BUS
FILTER TIME
PHASES
too quickly
MOTOR ROTATING TOO FAST
PRECHARGE
= 400µsec. If the motor is rotating too quickly the next Hall
Precharge and hall effects filtering time description
400 us
T∆zc’
400 us
T∆zc’
400 us
T∆zc’’
T∆zc’/576
PHASES EXCITED
U
Tel
T∆zc’’/576
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