24VDC Output Using INN260x Or INN2904
I need a 24VDC power supply and would like to use the INN260x or INN2904 family of switchers. However, the chip datasheet specification limits VO pin to 15V and FWD pin to +150V. A 24VDC supply would exceed the limits on both of the those pins. There is not enough description on the FWD to allow me to make a resistor divider since it simply states "A 47 Ω, 5% resistor is recommended to ensure sufficient IC supply current. A higer or lower resistor value should not be used as it can affect device operation such as the synchronous rectifier drive timing." Any ideas to add to your circuit DER-531 in order to accomplish this?
Comments
Just say that I have designed a power supply using the Inn2904k with 24v@0.5A output. I have used a 7812 regulator to connect Vout pin and it works perfect. The design is based on RDR-531.
Thanks.
Hello Arttong,
The FWD voltage depneds on the Vor you choose for the design. Only with extream low Vor you will let FWD higher than 150V. If you choose a proper Vor, you will not get FWD higher than 150V.
For the Vo pin, you can add a biplor and a zener to clamp the voltage at Vo pin lower than 12V. With the biplor collector to output positive and a 11V zener connected between the base at secondary return. The emitter of the biplor connect to the Vo pin.
Best Regards
Jia