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.

The current-control transconductance operational amplifier can be fully compensated. Both

its output and negative input are directly accessible for external compensation components.

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

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.

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