Electronics > Beginners
9-bit Addressable Latch Required
<< < (4/4)
boB:

--- Quote from: Ian.M on July 08, 2018, 08:54:05 pm ---As I said 12 hours ago: TPIC6C595 + 1 MOSFET.   Its an 8 bit shift register that's controlled like a 74HC595, but has 30V 100mA open drain outputs.

--- End quote ---

Interesting part.  So, with the double-D FFs, looks like this could work and possibly without a FET if the LED current is within spec.

Wouldn't this require an extra microprcessor pin for the two clocks or maybe an inverter for double-edge clocking to get that
extra serial output to work right ?

boB
Ian.M:
Its not relevant to the O.P's problem but there are also the TPIC6B595 - 50V, 150mA and the TPIC6A595 - 50V, 350mA in the same family. 

If you don't care about the data rippling across all the LEDs as its updated *, you only need two pins:  Clock  SRCK and RCK with one of them, and drive SER_IN and the MOSFET (via a 470R gate resistor so its gate capacitance doesn't slug the SER_IN risetime) with the other.  N.B. that configuration takes nine clock pulses to load a byte.   

* Given a fast enough MCU it can be updated in under 10us, so the ripple flicker is negligible.  Even if its 100 times slower, a 1ms ripple flash will barely be perceptible even in dim lighting
Docara:
Hello Everyone,

Thank you all for the replies.

I couldn't see a 'Solved' button anywhere.

I am more than likely going to use either the MCP23017, MCP23S17 or PCF8575 16bit port extender and transistors to drive the (3x3) 12V LED's.

The way the internals are organised makes other things easier for me - combinations of changing colours, flashing. Additionally the use of SPI or I2C to control things is also a massive for pin count reasons.

I consider the question answered.

Thanks again

Navigation
Message Index
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod