May be handy for those building custom PSUs, bench supplies - Page 1
Forum section: electronics / projects

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 03, 2018, 07:35:38 pm
content: https://www.diodes.com/assets/Datasheets/AP4313.pdfAt a glance, should be easy to set voltage and current arbitrarily, given an aux supply to keep the thing running of course. Only catch is the internal reference isn't accessible, so you'll have to add your own (the TL431 seems inescapable,or you can use a more precise ref of course). Semantically inelegant, but the price is right and the circuit can't be much simpler.Single stage isolated bench supply, anyone?Tim

author: prasimix
author_rank: Unknown
timestamp: October 03, 2018, 08:08:51 pm
content: Interesting. Looks like contender to TI'sTL103Wbut cheaper.

author: viperidae
author_rank: Frequent Contributor
timestamp: October 04, 2018, 04:57:21 am
content: It's two open collector opamps and am internal voltage reference. I'm confused as to why it's so great?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 04, 2018, 07:12:55 am
content: You can do it with a TL431 and a dual op-amp and a gazillion resistors, sure. If you've got the space!Tim

author: bd139
author_rank: Super Contributor
timestamp: October 04, 2018, 07:52:31 am
content: Very interesting - I have an application for this (SLA charger). Thanks for posting.Could this be the new LM723?

author: Berni
author_rank: Super Contributor
timestamp: October 04, 2018, 07:56:54 am
content: Neat, im going to have to keep this in mind.Why is it so great? Its a tiny chip that less passives around it to work while also being cheap.

author: bd139
author_rank: Super Contributor
timestamp: October 04, 2018, 07:59:55 am
content: Pricing is *very* low. Don’t think you can do much better.https://lcsc.com/product-detail/Switching-Controllers_DIODES_AP4313KTR-G1_AP4313KTR-G1_C24445.html

author: mikerj
author_rank: Super Contributor
timestamp: October 04, 2018, 04:59:22 pm
content: Vref is around 60ppm/C from the characteristic curve; not great, but not horrific. With the space saving over a dual-op-amp and TL431 you can glue a transistor and NTC on the top and ovenise it

author: David Hess
author_rank: Super Contributor
timestamp: October 05, 2018, 03:08:33 am
content: I get the feeling it is only intended to drive slow optocouplers. It is too bad the datasheet does not list any dynamic characteristics. I hate the whole transconductance output with loop compensation back to the inverting input thing but the 723 has that also.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 05, 2018, 07:53:56 am
content: The sample circuits are for an isolated switched mode supply and thus relatively slow. Having a emitter follower output stage usually does not need very fast external control either, so this should be OK. However having a current controlled output stage (e.g. common emitter or common source) can be tricky, as this usually needs a rather fast control loop and for the design a well known one. The low (0.5 mA) supply current suggests that it might not be that fast. Due to the low current and very likely a band-gap reference I would not expect the low noise of the 723.The trans-conductance output is handy when it comes to combining the current and voltage control, as chances are the saturation (0 current) is well behaved. The voltage can go down to the 200 mV range - can't do that with diodes.So it may be an alternative for a small linear supply - though chips like LM1117, LP2951 are not not that bad either. The main difference would in a better, more flexible current control. Still not very practical for a user adjustable (e.g. lab supply).