BA6859AFP-Y_10 Datasheet, PDF (15/18 Pages) Rohm – 1ch Spindle Motor Driver ICs

BA6859AFP-Y,BA6664FM,BD6671FM
Technical Note
●FG Signal Output / FG2 Signal Output
The FG signal output/FG2 signal output terminals are for detecting the motor rotation speed. The output frequency of FG2
signal is three times higher than the FG frequency signal output. So, it is suitable for the slow speed rotation detection.
However, due to the Hall device variation and other reasons, the duty cycle may not reach 50% in some instances.
H1+ + ^H1
H1- -
H2+ + ^H2
H2- -
FG2
H3+ + ^H3
H3- -
FG
Fig. 16
H₁ waveform
H₂ waveform
H₃ waveform
FG waveform
FG2 waveform
●Notes for use
Fig. 17
(1) Absolute maximum ratings
This product is subject to a strict quality management regime during its manufacture. However, damage may result if
absolute maximum ratings such as applied voltage and operating temperature range are exceeded. Assumptions should
not be made regarding the state of the IC (short mode or open mode) when such damage is suffered. A physical safety
measure such as a fuse should be implemented when use of the IC in a special mode where the absolute maximum
ratings may be exceeded is anticipated.
(2) Connecting the power supply connector backward
Connecting the power supply connector backwards may result in damage to the IC. Insert external diodes between the
power supply and the IC's power supply pins as well as the motor coil to protect against damage from backward
connections.
(3) Power supply lines
As return of current regenerated by back electromotive force of motor happens, take steps such as putting capacitor
between power source and GND as an electric pathway for the regenerated current. Be sure that there is no problem with
each property such as emptied capacity at lower temperature regarding electrolytic capacitor to decide capacity value. If
the connected power supply does not have sufficient current absorption capacity, regenerative current will cause the
voltage on the power supply line to rise, which combined with the product and its peripheral circuitry may exceed the
absolute maximum ratings. It is recommended to implement a physical safety measure such as the insertion of a voltage
clamp diode between the power supply and GND pins.
(4) GND potential
Ensure a minimum GND pin potential in all operating conditions.
(5) Setting of heat
Take the power dissipation Pd) into account for practical application and make thermal design with sufficiently margined.
(6) Pin short and mistake fitting
Use caution when orienting and positioning the IC for mounting on printed circuit boards. Improper mounting may result
in damage to the IC. Shorts between output pins or between output pins and the power supply and GND pins caused by
the presence of a foreign object may result in damage to the IC.
(7) Actions in strong magnetic field
Use caution when using the IC in the presence of a strong magnetic field as doing so may cause the IC to malfunction.
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2010.06 - Rev.A