General description

VIPER26K

16/28

DS12978 Rev 1

In the case of isolated power supply, the internal error amplifier has to be disabled (FB pin

shorted to GND). In this case an internal resistor is connected between an internal reference

voltage and the COMP pin.

The current loop has to be closed on the COMP pin through the optocoupler in parallel with

the compensation network. The VCOMP dynamics range is between VCOMPL and VCOMPH.

When the voltage VCOMP drops below the voltage threshold VCOMPL, the converter enters

burst mode.

When the voltage VCOMP rises above the VCOMPH threshold, the peak drain current will

reach its limit, as well as the deliverable output power.

Figure 21. Feedback circuit

Figure 22. COMP pin vs. IDLIM