Half-wave rectified input to LNK362
Posted by: elikd
on
Hello,
I am designing a low-power (1W) buck supply using an LNK362. I'm looking to use a half-wave rectified input since I need the supply to be neutral-wire referenced, and was wondering if PI has any input on this use in a 240vac application. If I don't place enough input capacitance to keep the switcher running during the negative half-cycle, I've found that the inductor I'm using (SMT 680uH) starts to product audible noise.
Would that be a non-recommended application for this chip or is the current-limiting circuitry capable of dealing with this turn-on event on every line-cycle?
Thanks.
Comments
Dear Elikd:
you may take a look to DI-39 (Buck, Single diode rectification ) and EPR-48 (Buck 2 diode rectification). Although EPR-48 uses 2 diodes at input, the report explains why 2 diodes instead of only single diode. Depending on your application, you may be able to use single diode.
You may use LNK TN family for your design. If so, PI Expert program support the buck topology with full or half rectification. If you decide to use LNK XT family, you still can develop a buck converter but we can not give you support. Sincerly PI-Worf
PI-Worf,
In the DI-139 example you cite (Buck, Single diode rectification), it's hard to estimate, but the C2 cap looks like it might discharge entirely during the negative half-cycle at 85VAC. Is that the case, and if so, I presume PI has no issues with this mode of operation (turning itself off every line cycle).
Thanks.
In the DI-139 example you cite (Buck, Single diode rectification), it's hard to estimate, but the C2 cap looks like it might discharge entirely during the negative half-cycle at 85VAC. Is that the case, and if so, I presume PI has no issues with this mode of operation (turning itself off every line cycle).
Thanks.
