74HC595 good replacement for slightly higher current

Ok so i am designing a small pcb that uses the 74HC595 to drive 21 LED's, 3 LED's per pin making a 7 segment display. I do not exceed the max current for each pin (ie. 35mA) however when the number 8 is shown it can be as high as 130mA. The total max current for VCC/GND is 70 mA.

So does anyone know of a very slimier IC that will replace this one and have the same functionality and I know there is some that will sink instead of source i would rather source the 5V in this design. Or if there is a small SMD ic that can act as a buffer that would work perfectly without inverting the logic please let me know.

TPIC6B595

A2981/2982 are 8-channel source drivers.

MIC2981 is available from digikey.

Oops! :astonished:

rob40855:
I know there is some that will sink instead of source I would rather source the 5V in this design.

Question though is - why?

Availability of the TPIC6B595 would seem to be better than all those other options.

Paul__B:
Oops!

"Oops" nuthin'.

The TPIC device does the 595 thing and offers more current capability, but its outputs are open drain.
The 2981 devices are "drivers", "buffers", but that's all; there's no shift register.

rob40855:
Ok so i am designing a small pcb that uses the 74HC595 to drive 21 LED's, 3 LED's per pin making a 7 segment display.
So does anyone know of a very slimier IC that will replace this one and have the same functionality and I know there is some that will sink instead of source i would rather source the 5V in this design. Or if there is a small SMD ic that can act as a buffer that would work perfectly without inverting the logic please let me know.

So, given a) "slimier", b) "same functionality", c) and "i would rather" --
I figured
a) can't help
b) shift register uber alles
c) oh well, get over that.

rob40855:
So does anyone know of a very slimier IC that will replace this one and have the same functionality and I know there is some that will sink instead of source i would rather source the 5V in this design. Or if there is a small SMD ic that can act as a buffer that would work perfectly without inverting the logic please let me know.

Suggestion: 74AC164.

According to Crossroads' interpretation of the data sheet, can source up to 200mA per chip. My interpretation of the data sheet is that the data sheet is worded ambiguously! I hope Crossroads is correct.

Note that this chip has no latch pin, so as soon as you clock data bits in, the outputs change, it won't wait until 8 bits have been shifted in. Given that you are not multiplexing a multi-digit display, I don't think this will be a problem.

Paul

cd74AC164
http://www.digikey.com/product-search/en?vendor=0&keywords=74ac164
±24mA Output Drive Current
DC VCC or Ground Current, ICC or IGND (Note 3) . . . . . . . . .±100mA
NOTES:
3. For up to 4 outputs per device, add ±25mA for each additional output.

Seems pretty clear it can handle 8 x 20mA outputs.

I use a dozen of them on my 9x9x9 LED cube driver board with 100 ohm current limit resistors, with N-channel MOSFETs to sink current per layer. None were getting hot with 20mA source current to 8 LEDs.
2A wallwart was choking on the 1.62+A current draw, changing to 4A supply worked much better.