Flybuck Cockroft-Walton

Phil Hobbs · 2019-12-03T21:33:56+00:00

Hi, All, This is for a flexible photoreceiver board intended for use with PIN diodes, silicon and InGaAs APDs in both linear and SPAD mode, and MPPCs. We've been doing a fair number of proof-of-concept systems for technology licensing, and it would be nice to have a few dozen front end boards that can be used for everything from nanowatt PIN diode detectors to an MPPC front end that will go from photon counting to about 3 mA anode current in one range. The bias generator is this C-W thing (.asc appended below) followed by an op amp controlled HV transistor voltage regulator. It's driven by the switch pin of a TPS560430F 1 MHz sync buck which also generates a -6V rail from 24V, so the input waveform has an 80% duty cycle. Unlike a lot of sync bucks, this one actually does keep PWMing right down to zero load. (I got bitten by a lying datasheet last time I tried doing this--now I never use a new switcher without getting the eval board.) Using pop options, it'll make anything from near zero down to -250V. Silicon APDs often need 220V or thereabouts, MPPCs are often around 50-70. Doing one fancy board like this means that we don't have to pay to build N versions of more or less the same technology--we pull one out of the bin, mod it for the application, and away we go. This is the high-voltage version, which needs to have its short-circuit current limited to a safe value. (There's also a LND150 in series with the amp output, as well as the 600 mA cycle-by-cycle current limit of the buck, so this is belt-and-suspenders.) The main bit of ugliness is ringing caused by the inter-winding capacitance of the transformer, but it looks like it'll work pretty well. Cheers Phil Hobbs ------------- Version 4 SHEET 1 1868 692 WIRE -512 80 -608 80 WIRE -512 96 -512 80 WIRE -208 112 -336 112 WIRE -176 112 -208 112 WIRE -80 112 -176 112 WIRE 16 112 0 112 WIRE 144 112 96 112 WIRE 272 112 208 112 WIRE 416 112 272 112 WIRE 608 112 480 112 WIRE 752 112 608 112 WIRE 960...

Dec 03, 2019 140 Replies

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DecadentLinuxUserNumeroUno 6 years ago

Johnny B Good wrote in news:RaPIF.2$ snipped-for-privacy@fx11.am:

You're a goddamned retard.

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Most likely because you are just as clueless as the SloTard is.

Setting somreone straight?

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Flybuck Cockroft-Walton

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