TPIC6B595 wirinig for daisy chain


I’m at it again. Wanted to get the TPIC6B595s working in a daisy chain. There are 10 pins on these ICs with two pins having “no internal connection” according to the datasheet - which was new to me.

But, there are two pins with labels I can’t work out what to do with them. They are labeled SRCLR, and G.

My schmatic is also attached for reference.



It's on the first page of the datasheet:

When SRCLR* is low, the input shift register is cleared. When output enable (G*) is held high, all data in the output buffers is held low and all drain outputs are off. When G is held low, data from the storage
register is transparent to the output buffers.

When SRCLR* is low, the bits you have shifted in are all reset to zero. It's equivalent to shifting all zeros into the shift register.

When G* is low, the outputs of the chip follow the values you shifted into the shift register (when latched), when G* is high, the data from the shift register is ignored, and the outputs are off, no matter what.

The overbar and the star indicate that the inputs are active-low.

In conclusion, wire SRCLR to the logic supply (5V/3.3V), and wire G to ground.


Edit: the LEDs in your schematic are the wrong way around.

Remember the 595 questions from your earlier thread? The pins are the same function but different names on both chips:

74HC595 TPIC

~OE ~G

Connect SRCLR to the Arduino RESET pin. That will initialize the outputs to zero, instead of the random state they are in at power up time.

Never use light yellow lines on a schematic. It was several minutes until I saw them. :slight_smile:

Thank you. I get in front of a datasheet and I misinterpret a log of what I see. Some of it's confidence at this point. Not wanting to make an electrical mistake.