STMicroelectronics L6562A Evaluation Board STEVAL-ILL016V2 STEVAL-ILL016V2 STEVAL-ILL016V2 Fiche De Données

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The voltage control transconductance operational amplifier can be fully compensated. Both 
of its output and negative input are directly accessible for external compensation 
components.

An example of a suitable compensation network is shown in 

It consists of a 

capacitor C

VC1

 = 2.2 nF and a resistor R

CV1

 = 470 k

Ω in series. 

The current-control transconductance operational amplifier can be fully compensated. Both 
its output and negative input are directly accessible for external compensation components. 
An example of a suitable compensation network is shown in 

It consists of a 

capacitor C

IC1

 = 2.2 nF and a resistor R

IC1

 = 22 k

Ω in series. In order to increase the 

stability of the application it is suggested to add a resistor in series with the optocoupler. An 
example of a suitable R

LED 

value could be 330 

Ω in series with the optocoupler. 

Under start-up or short-circuit conditions if the device is supplied from SMPS output and the 
output voltage is lower than Vcc minimum the current regulation is not guaranteed. 

Therefore, the current limitation can only be ensured by the primary PWM module, which 
should be chosen accordingly.

If the primary current limitation is considered not to be precise enough for the application, 
then a sufficient supply for the device has to be ensured under any condition. It would then 
be necessary to add some circuitry to supply the chip with a separate power line. This can 
be achieved in numerous ways, including an additional winding on the transformer. 

The following schematic shows how to realize a low-cost power supply for the device (with 
no additional windings).

Vout

 

Iout

Voltage regulation

Current regulation

 

(

 

Vcc of the device independent of output voltage)

Vout

 

Iout

Voltage regulation

Current regulation

 

(

 

Vcc of the device independent