Motor driver ICs
FInput / output circuits
(1) Hall and ECI inputs
BA6825FS / BA6826FS
(2) Coil output
FCircuit operation
(1) The signal from the Hall device is amplified by the
Hall amplifier and then supplied to the driver circuit. The
driver gain, which is constant, is regulated by changing
the Hall amplifier gain with the input current on the output
current control pin (ECI pin). The motor rotational speed
is sensed by the FG, and the output of which is F / I-con-
verted and supplied to the ECI pin as a feedback signal,
so that a constant rotational speed is maintained as fol-
lows :
(1) The motor speed decreases.
(2) The speed control IC outputs a feedback signal to the
ECI pin.
(3) The Hall amplifier gain increases.
(4) The output current increases.
(5) The motor speed increases.
(2) When the voltage on Hall INφ1 ()) is higher than the
voltage on Hall INφ1 (*), an output current flows from
OUT1 (*) to OUT1 ()) according to the voltage differen-
tial. When the voltage on Hall INφ1 (*) is higher, on the
other hand, an output current flows from OUT1 ()) to
OUT1 (*).
Similarly, when the voltage on Hall INφ2 ()) is higher than
the voltage on Hall INφ2 (*), an output current flows from
OUT2 (*) to OUT2 ()) according to the voltage differen-
tial. When the voltage on Hall INφ2 (*) is higher, on the
other hand, an output current flows from OUT2 ()) to
OUT2 (*).
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