I'm attempting to build my own LED display for my clocks, but ran into a block...
HT1632c LED driver IC can drive 32 ROW /8 COM or 24 ROW & 16 COM. Am I correct assuming I can drive more Common Cathode bicolor 8x8 matricies than Common Anode with this IC?
Or is it possible that this IC supports both CA and CC matrices?
I found this in datasheet, but not exactly understand what it means:
The HT1632C has a 256 (32x8) and 384 (24x16) pattern
LED driver. It can be configured in a 32x8 or 24x16 pattern
and common pad N-MOS open drain output or
P-MOS open drain output LED driver using the S/W configuration.
This feature makes the HT1632C suitable for
multiple LED applications.
Does it mean that by switching between N-MOS and P-MOS I can switch direction of the current and use either common anode or common cathode LED Matrix?
Look at page 13 - the ROW outputs connect to Anodes, the COL output connect to cathodes.
So nominally it was designed for common cathode display. Especially RG or RGB LED matrices.
Or vice versa if additional transistors are used, see page 15. Lot more hassle to use common anode when common cathode displays are available.
Just FYI, in case someone has similar question, I got my answer from another forum (Adafruit).
The current limits on the pins are wrong for driving CA matrices.
Each ROW pin can source 70mA and sink 16mA. Each COM pin can sink 350mA and source 60mA.
The natural orientation is to have a COM pin connected to the cathodes of 8 rows, and a ROW pin connected to the anode of each LED. Each ROW pin supplies enough current to drive its LED, and the COM pin can sink enough current to handle all the ROW currents.
The flipped arrangement (COM sourcing, ROW sinking) is there so you can use the chip to drive larger matrices with transistors. There are diagrams of the connections on page 15 of the datasheet.
So yeah, if you want to drive LED matrix directly from HT1632c chip, you have to use Common Cathode.
CrossRoads:
Look at page 13 - the ROW outputs connect to Anodes, the COL output connect to cathodes.
So nominally it was designed for common cathode display. Especially RG or RGB LED matrices. http://www.adafruit.com/datasheets/ht1632cv120.pdf
Or vice versa if additional transistors are used, see page 15. Lot more hassle to use common anode when common cathode displays are available.
Thanks! Looks like you posted at the same time as I did But yeah, looks like I'm stuck with Cathodes
But yeah, looks like I'm stuck with Cathodes