INN3692 output out of control with high frequency noise

Posted by: N K DURGA RAO on 06/19/2023

We are designing Half bridge hard-switching converter with digital control for charger and adaptor application. INN3692 used for generating bias power for the entire circuit. Bias is working fine when we checked individually. The moment when we connected half-bridge converter bias output is going out of regulation and bias output over voltage is acting and it is going to hick up mode. We observed half-bridge converter mosfet is very fast, mosfet ringing noise is disturbing the INN3692. When we reduced the rise time and fall time of the mosfet the converter started working fine, but that will increase the losses in the half-bridge converter.

Here comes the doubt, INN3692 feedback is inductive coupled. Is inductive coupling feedback is prone to magnetic field disturbance? The magnetic filed noise generated by Half-bridge converter disturbing the INN3692 Feedback. If It is magnetic field sensitive please let us know.

Comments

Hi N K Durga Rao

Good Day!

Thanks for using Power Integration IC.

Most of the INNO IC are place bottom side and on directly on the top of it the Flyback transformer is located.

Is it possible to share us the schematic and specs of the INN3692 power supply (Vin, Vo, Io).

Thanks

PI-Chloe

Hi,

Schematic attached. Half-Bridge Converter primary is powered by 15V_LS and secondary is powered by 11V. When half-bridge converter is ringing with high dv/dt, INN3692 bias is generating 23V output.

Attachment	Size
st23-026_hybrid_ac-dc_converter-20230512_1500.pdf	436.86 KB

Hi N K Durga Rao

Good Day!

Based on our schematic review., we don't see any concern on the schematics.

We can look to the layout of the Power supply.

-PFC_OUT should be star connected to the Bulk Cap

- IN_GND should be star connected to the Bulk Cap

-BPP Cap should be directly/near to the pin of the IC with Size code 0805 or larger.

-BPS Cap should be directly/near to the pin of the IC with Size code 0805 or larger.

-FB cap C104 should be directly/near to the pin of the IC

If you are willing to provide the PCB lay out, we can help you.

Thanks

Regards

PI-Chloe