Could someone help decipher this Alibaba description?

[rp58]

https://www.aliexpress.us/item/3256805086851428.html?src=google&afSmartRedirect=y&gatewayAdapt=glo2usa

It is a DC-DC Constant Current Boost converter.  You set the output current according to two resistors.

*The drive current is equal to the set value of resistance 1 plus the set value of resistance 2
*The driving current calculation formula is: current=0.1/resistance value (the default resistance of the board 1 and 2 are 0.25 Ω, the current is about 0.4A when the ISET is not short-circuited, and the current is about 0.4A+0.4A when the ISET is short-circuited). Note that the calculation here is only the approximate current, and the actual current will have some error according to the actual application. Please refer to the following curve for details.

Are r1 and r2 in parallel, and I replace both of them?  Or is r2 optional and I only use it if I can't find an r1 in the exact value I need?

The description also implies I can feed it low voltage A/C.  Is that right?

My application is to drive a 20w LED requiring 32vdc at 700ma from 12vac landscape transformer.  If I can really skip the rectifier and filter, that would be a bonus.  Is it really as easy as swapping in a R047 resistor?

[Jwillis]

From what I gather is when ISET is not shorted only one of the resistors is used . 0.1/0.25=0.4A . When ISET is shorted then both resistors are in parallel. 0.1/0.125=0.8A .The part that says "and the current is about 0.4A+0.4A when the ISET is short-circuited" confirms the current is around 0.8A

As for the AC part, I can't 100% be sure. It says it can support up to 65VAC. Get 2 and see if one blows up with AC 

[torch]

I read it that the input voltage can be 10-100VDC or 10-65VAC.

[rp58]

Thanks, you've given me enough confidence to try a couple.  Usually you have to take the Chinese specs with a grain of salt, but I am hopeful.

[BillyO]

I agree on the ISET jumper putting the two resistors in parallel, however, I am not sure that it will handle zero-crossing AC.  I think they mean it will handle something like the input voltage swinging between 20V and 85V (example) and maintain current within spec.  Not -30V to 30V.

[rp58]

Rats, I thought that AC implied zero crossing.  So maybe it means I have to rectify the AC, but not filter it.