It is possible to verify that the L292 works in "closed-

loop" conditions during the entire motor current

rise-time: the voltage at pin 7 inverting input of the

error amplifier) is locked to the reference voltage

amplifier.

The previous linear analysis is correct for this ex-

ample.

Descresing the

ξ value, the rise-time of the current

decreases. But for a good stability, from relationship

(6), the maximum value of

ξ is:

CLOSED LOOP SYSTEM BANDWIDTH.

A good choice for x is the value 1 /

√2. In this case :

(s) =

0.044

1

1

The module of the transfer function is :

|

|

=

0.044

2

√

1

[

The cutoff frequency is derived by the expression (9) by putting |

|

0.044

(−3 dB), from

which :

0.9

=

0.9

2

1

2

4

(phase margin = 45

°)

b) Large signal reponse

The large step signal response is limited by slew-

rate and inductive load.

In this case, during the rise-time of the motor

current, The L292 works is open-loop condition.

(8)

(9)

9/12

L292