STMicroelectronics L6562A Evaluation Board STEVAL-ILL016V2 STEVAL-ILL016V2 STEVAL-ILL016V2 Hoja De Datos
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STEVAL-ILL016V2
Application information
TSM1052
10/15
Figure 16. Output voltage versus output current
4.3 Compensation
The voltage control transconductance operational amplifier can be fully compensated. Both
of its output and negative input are directly accessible for external compensation
components.
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
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
example of a suitable R
LED
value could be 330
Ω in series with the optocoupler.
4.4
Start up and short circuit conditions
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.
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.
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.
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).
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