Using HT16K33 with Large SevenSegment displays

I have a requirement to drive 12 nos of large seven segment displays … these are displays with segment drive voltage of 5.6V and current of about 20mA or so. ( three groups of 4 digits each )

I was wondering if a single HT16K33 could be the main driver and linked to the Common cathode displays through some buffer ICs ?

Since the HT16K33 can drive 16 digits i dont have to resort to any daisy chaining of the controllers .

Or is there any better way to do this ?

Any links or ideas to do this ?

A single ht16k33 has only 8 common driver pins, which can sink 160mA each. If you paired up the digits, the common cathodes would need to sink 7 X 2 X 20mA = 280mA, which would overload them. So I think you would need to drive each digit independently, which means half the segment pins would be wasted and you would need two ht16k33 to drive all 12 digits. And on top of that you have the 5.6V segment forward voltage, which means you need at least a 6.5V supply, I suspect.

To drive all 12 digits, you might need 14 channel buffers on the high side to switch the 6.5V+ supply and 6 channel buffers on the low side to switch the current from each pair of digits.

This is really awkward...

Have you purchased the digits yet? Are they also available as common anode?

Thanks Paul.

What you wrote is on the dot. Reason why I sounded it here is that to me it looked pretty awkward anyway to start with.

I think the HTK is a great chip to drive the alphanumeric segment displays and without any buffering in between. Meaning the display size cannot be larger than say 0.5 inches ?

No I have not bought any components. But I have many CA seven segment displays with me. I love the SAA 1064 but that’s history now.

So what other option would you suggest ??

What do you call large.
2" 7-segment could already have four LEDs in series per segment (and a Vf of 8-10volt).

An easy/cheap way is common anode displays, and the TPIC6B595 (ebay).
No matrixing, so full brightness.
Limits are 50volt and 100-150mA per segment.
Sparkfun.com has big displays, and backpack driver boards (with the TPIC6C596).
Leo..

There is mic5981 which is like tpic6b595, but with high voltage/current sourcing.

You could use one per digit with no multiplexing. The outputs of the chip are not constant-current, so you would need a lot of series resistors in this case.

Alternatively you could use 2 X mic5981 and 1 X tpic6b595 or 1 X mic5981 and 2 X tpic6b595 and multiplex by digit or by segment.