TDA5140A Datasheet, PDF (15/24 Pages) NXP Semiconductors – Brushless DC motor drive circuit

Philips Semiconductors
Brushless DC motor drive circuit
Product specification
TDA5140A
Fig.10 Timing and the FG and PG IN signals.
The special PG pulse is derived from the negative-going
zero-crossing from the MOT3 output (pin 16). The external
PG signal (PG IN on pin 5) must sense a positive-going
voltage (>80 mV) within 1.5 to 7.5 commutation periods
before the negative-going zero-crossing in MOT3
(see Fig.10).
The voltage requirements of the PG IN input are such that
an inexpensive pick-up coil can be used as a sensor
(see Fig.11).
Example: If p = 6, then one revolution contains 6 × 6 = 36
commutations. The tolerance is 6 periods, that is 60
degrees (mechanically) or 6.67 ms at 1500 rpm.
If a PG sensor is not used, the PG IN input must be
grounded, this will result in a 50% duty factor FG signal.
2.2 kΩ
PG IN
22 nF
GND2
MBD696
Fig.11 Pick-up coil as PG sensor.
April 1994
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