Tool/software:
Dear TI Support,
I used the LM5181 IC in order to produce an isolated power supply with the following characteristcs: Vin = 12 V [9 - 13 V], Vout = 3.6 V, Imax = 600 mA.
Here you can see my schematic:
The output voltage that I measure on TP2 in 1.6 V instead of 3.6 V and the switching frequency that I measure on the SW pin is 122 kHz.
Do you have any suggestion in order to have a correct output voltage?
Thank you for you support,
Stefano
Stefano,
Checking your schematic components, I noticed that the zener diode clamp that you are using has a 4.3V voltage clamp. The clamp voltage of the zener diode must be higher than the reflected output voltage (see equation below from datasheet). In you case, it is recommended to use a clamo voltage of Vdz_clamp=1.5*4*(3.6+0.7)=~26V. Please, update the zener diode. What is most likely happening is that when the MOSFET is off and the secondary diode is conducting, the voltage at Lmag is clamped to 4.3V, affecting the output voltage.
Thank you
