I was comparing the typical application schematics between the MC34063 and the NCP3063.

The NCP3063 shows pin 8 (driver collector) is NOT connected while 34063 does.

Huh?
I'm looking on page 11 of 19 of the PDF.
SWC is pin 1. It's connected to the junction of the inductor L101 and the diode D101.

Also, the application shows 5 total capacitors for the NCP, only 3 for the 34063.

Why do you need a .1uF capacitor in line with polarized electrolytic caps? That's where the 2 extras are coming from.

Higher switching frequency. The small caps help a great deal with transient suppression at high frequencies.
Oh, I blew it on the input cap; I linked to a 100uF low ESR; it needs to be higher.

Why is the driver collector not connected in the NCP version?

It is. Try downloading the PDF again; you might have a corrupted version.

One last question, should the 12V input ground be independent from the (in my case) 18V output ground?.

No, absolutely not.

On your board, all of the grounds must be common. Use short, fat traces to minimize inductance.

It wouldn't be a bad idea to run the ground and power to your LED array from the board itself.

 

Huh?
I'm looking on page 11 of 19 of the PDF.
SWC is pin 1. It's connected to the junction of the inductor L101 and the diode D101.

I'm on the same page. I'm referring to pin 8 that says N.C.

Higher switching frequency. The small caps help a great deal with transient suppression at high frequencies.
Oh, I blew it on the input cap; I linked to a 100uF low ESR; it needs to be higher.

Ok, and crap...lol. What defines capacitor values? How would you determine how much capacitance you need?

It is. Try downloading the PDF again; you might have a corrupted version.

See attachment. Pin 8 shows as Driver Collector on the MC34063A and is connected through a 180Ω resistor to the output of Rsc. On the NCP3063 pin 8 is always referenced as unconnected. Pin 1 is the SWC, maybe you read my post wrong, or I'm just blind to something...

No, absolutely not.

On your board, all of the grounds must be common. Use short, fat traces to minimize inductance.

It wouldn't be a bad idea to run the ground and power to your LED array from the board itself.

Ok, all grounds are the same plane on my current board, and I have large copper areas for ground planes, and wider traces than component traces. All components and LEDs are on the same board, so no problem running ground and power to the array from the board.

 

I'm on the same page. I'm referring to pin 8 that says N.C.

N.C. means that there is no internal connection in the IC.
It'll be OK if you connect the thing up using the schematic on that page using the values I supplied.

Ok, and crap...lol. What defines capacitor values? How would you determine how much capacitance you need?

It should be OK, I got those numbers from the spreadsheet.

If need be, you could always add another cap later; like 330uF.

See attachment. Pin 8 shows as Driver Collector on the MC34063A and is connected through a 180Ω resistor to the output of Rsc. On the NCP3063 pin 8 is always referenced as unconnected. Pin 1 is the SWC, maybe you read my post wrong, or I'm just blind to something...

OK, the MC34063A has external connections for the Darlington driver. You can elect to not use the Darlington. The NCP3063 always uses the Darlington driver, there isn't an external connection to avoid using the Darlington.

Ok, all grounds are the same plane on my current board, and I have large copper areas for ground planes, and wider traces than component traces. All components and LEDs are on the same board, so no problem running ground and power to the array from the board.

Sounds like you'll be good to go then.

 

OK! I totally get it now. As always, thanks Sarge, huge help...huge.

Best!

 

Last question:

Due to a math error on my part, I need 290mA of current for my LED array, not 240mA. Will I need to adjust the value of Rsc to achieve this or will I be ok with the 0.15 Ohm 1/2W resistor there already?

Or will I be required to change something other than Rsc for the extra 50mA?

 

Last question:

Due to a math error on my part, I need 290mA of current for my LED array, not 240mA. Will I need to adjust the value of Rsc to achieve this or will I be ok with the 0.15 Ohm 1/2W resistor there already?

Or will I be required to change something other than Rsc for the extra 50mA?

You won't need to change anything.

Rsc was kept low to keep efficiency high.
It's high enough to protect the IC switch.