TDF5140 datasheet(15/19 Pages) PHILIPS

15 / 19 page

1999 March 15

Philips Semiconductors

Product speciﬁcation

Brushless DC motor drive circuit

TDF5140A

Fig.8 Timing and the FG and PG IN signals.

ndbook, full pagewidth

MGH319

tolerance on PG IN

PG IN

MOT3

PG/FG

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.8).

The voltage requirements of the PG IN input are such that

an inexpensive pick-up coil can be used as a sensor

(see Fig.9).

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.

MBD696

2.2 k

Ω

PG IN

GND2

22 nF

Fig.9 Pick-up coil as PG sensor.

TDF5140 Datasheet(PDF) 15 Page - NXP Semiconductors