L6258 STMicroelectronics, L6258 Datasheet - Page 18

• Manufacturer Part Number: L6258
• Manufacturer: STMicroelectronics

Specifications of L6258

• Operating Current: 15mA
• Motor Controller Type: PWM Motor Controller
• Package Type: PowerSO
• Operating Supply Voltage (min): 12V
• Operating Supply Voltage (typ): 34V
• Operating Supply Voltage (max): 5.25V
• Lead Free Status / Rohs Status: Not Compliant

PWM current control loop
3.3
18/32
Moreover, having the two references Tri_0 and Tri_180 a triangular shape it is clear that the
transfer function of this block is a linear constant gain without poles and zeros.
Load attenuation
The load block is composed by the equivalent circuit of the motor winding (resistance and
inductance) plus the sense resistor.
We will considered the effect of the Bemf voltage of the motor in the next chapter.
The input of this block is the PWM voltage of the power amplifier and as output we have the
voltage across the sense resistor produced by the current flowing into the motor winding.
The relation between the two variable is:
so the gain of this block is:
where:
R
R
Because of the inductance of the motor L
L
S
= equivalent resistance of the motor winding
= sense resistor
Aload dB
Fpole
ACload
ACload dB
V sense
ACpw
Fpole
=
=
---------------------------------------- -
6.28
20
dB
=
=
⋅
=
V sense
-------------------- -
=
log
---------------------- R
R
=
⋅
v
-------------------------------- -
2π
12 10
----------------------- -
12
L
V out
out
20
20
1
L
----------------------- -
12
+
, the load has a pole at the frequency:
⋅
⋅
+
⋅
R
0.33
⋅
-------------------- -
R
+
log
0.33
log
1
S
L
0.33
–
=
L
+
⋅
3
----------------------
R L
L
2 24
------------- -
R
----------------------
R
1.6
⋅
S
=
R S
S
L
+
=
R S
163Hz
+
R S
–
R
=
31.4dB
S
29.5dB
L6258