L6258

Manufacturer Part NumberL6258
ManufacturerSTMicroelectronics
L6258 datasheet
 


Specifications of L6258

Operating Current15mAMotor Controller TypePWM Motor Controller
Package TypePowerSOOperating Supply Voltage (min)12V
Operating Supply Voltage (typ)34VOperating Supply Voltage (max)5.25V
Lead Free Status / Rohs StatusNot Compliant  
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L6258
Figure 10. Electrical model of the load
OUT+
OUT-
The schematic now shows the equivalent circuit of the stepper motor including a sine wave
voltage generator of the Bemf. The Bemf voltage of the motor is not constant, its value
changes depending on the speed of the motor.
Increasing the motor speed the Bemf voltage increases:
Bemf = Kt · ω
where:
Kt is the motor constant
ω is the motor speed in radiant per second
The formula defining the gain of the load considering the Bemf of the stepper motor
becomes:
we can see that the Bemf influences only the gain of the load block and does not introduce
any other additional pole or zero, so from the stability point of view the effect of the Bemf of
the motor is not critical because the phase margin remains the same.
Practically the only effect of the Bemf is to limit the gain of the total Aloop with a consequent
variation of the bandwidth of the system.
Bemf
R
L
L
L
R
S
(
V S Bemf
Vsense
ACload
=
---------------------
=
------------------------------------------------------------ -
Vout
V S Bemf
---------------------------- -
Acload
=
V S
V S Bemf
---------------------------- -
ACload dB
=
20
log
V S
PWM current control loop
to Sense
Amplifier
R
S
)
----------------------
R L
+
R S
V S
R S
----------------------
R L
+
R S
R S
----------------------
R L
+
R S
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