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
Before analysing the error amplifier block and the sense transconductance block, we have to
do this consideration:
Aloop
= Ax
+ Bx
dB
dB
Ax|
= ACpw|
dB
dB
and
Bx|
= ACerr|
dB
dB
this means that Ax|dB is the sum of the power amplifier and load blocks;
Ax|
= (29,5) + (-31.4) = -1.9dB
dB
The BODE analysis of the transfer function of Ax is:
Figure 7.
Ax bode plot
The Bode plot of the Ax|dB function shows a DC gain of -1.9dB and a pole at 163Hz.
It is clear now that (because of the negative gain of the Ax function), Bx function must have
an high DC gain in order to increment the total open loop gain increasing the bandwidth too.
3.4
Error amplifier and sense amplifier
As explained before the gain of these two blocks is:
Bx
= ACerr
+ ACsense
dB
dB
Being the voltage across the sense resistor the input of the Bx block and the error amplifier
voltage the output of the same, the voltage gain is given by:
dB
+ ACload|
dB
+ ACsense|
dB
dB
ib
=
Vsense Gs
PWM current control loop
1
------- -
=
Vsense
Rb
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