it is a cap charging ICs are there any alternatives to LT3750/LT3751 or other LT series cap charger ICs?

 

Before we start listing a bunch of substitutes ...
1) WHY can't you use an LT3750/LT3751
2) What feature are you looking for, that the LT3750/LT3751 does not have?

A Constant Current Source can charge a Cap.

 

Do you mean "cheaper" alternatives.

 

You can charge a cap using a flyback converter. Check out Ronald Dekker's site, "Flyback Converters for Dummies"; it does a great job of explaining a lot of things about boost and flyback converters.

https://www.dos4ever.com/flyback/flyback.html

Be VERY careful when experimenting with high voltage circuits!

 

There was a REPLY above me, regarding the CHARGE PIN, but now it is gone.

Step 1 = Pulse the SCR Gate which also SETS an S-R Latch and the <Charge Pin> to High, to Start the Charge Cycle
Step 2 = Wait for the <Done Pin> to go Low, which can also RESET an R-S Latch and the <Charge Pin> to LOW
Repeat, as needed ...

 

This sounds like manual labor involving buttons to discharge capacitor. Im trying to get this to fire automatically after the cap charges. But only to have the SCR conduct for at least 200mS before charging the cap agian.

Nowhere in my reply did I say, "manual labor" or "push a button".
It is 100% digital & 0% human interaction
The <Done Pin> going LOW transition, can create the beginning of your 200 ms SCR Pulse & RESET the S-R Latch
For 200 ms ... The SCR is ON or until the cap discharges, and the LT3750 is IDLE.
The end of the 200 ms SCR Pulse, can create the signal to start the next charge cycle - SET the S-R Latch
100% automatic re-triggering.