First PCB Design, hoping for feedback

[techy101]

Like the title says, this is my first PCB design. It's been through five or six revisions over the last month, and I've arrived at this. I was hoping that some of the folks on here could give me some constructive feedback on my design.

The purpose of this board is as a controller for a 10x10x10 LED cube using 595 shift registers. Each LED draws 20mA, so each ground layer control needs to be capable of sinking at least 2A of current. I'm using N-Channel MOSFET's for that job, being controlled by some Dual MOSFET Driver's. The board has headers on it for an Arduino Micro so it can simply be sandwiched on, and power comes from a standard MOLEX Drive Connector. 12V goes to the VH pins on the MOSFET Drivers as well as the Arduino, and 5V goes to the Shift Registers and VDD on the MOSFET Drivers. I'm including links to the Eagle Files (as a ZIP), and the relevant datasheets.


I've not really done work with transistors, so one of my concerns is that I've correctly designed them to sink the required current, and to switch in at least 100ns.


EAGLE Project folder:
https://www.dropbox.com/s/g76m0sy88i33z6d/LED CUBE BETA 4.zip


Shift Register Datasheet:
https://www.mouser.com/ds/2/405/schs353-263165.pdf


MOSFET Driver:
https://www.mouser.com/ds/2/465/fn6228-74213.pdf


Ground Sink MOSFET's:
https://www.mouser.com/ds/2/149/FDN359BN-80801.pdf




And a few pictures:

Update after being Smashed:

This is the almost present revision:

Here was the previous version:

And here was the very first try. (Never ever using the Auto Router again)

 

[FvM]

74HC595 has a maximum rating of 70 mA for GND and VCC terminals. This means, it can't drive more than 8.7 mA per LED if eight outputs are active.

If the LEDs are operated in time multiplex, you'll most likely want more than 20 mA per LED, otherwise they would light rather dim.

You don't need high current MOSFET drivers to drive small 3A FETs. It can run with a 100 ohm gate series resistor from HC595. Preferably use a logic level MOSFET with lower Rdson.

 

[techy101]

Thank you for the response. I can't believe I overlooked the max rating of the 74HC595 *head-desk*

I've been doing some research, and have come across the TPIC6B596DW as a possible alternative, and was wondering if I am correct that it would fit my needs.

As for driving the FETs, are you saying that it will work by simply putting a resistor between the shift register output pin and the gate on the FET? ie. (SHIFTREG PIN)----[RESISTOR]----{MOSFET GATE PIN}

Thank you!

 

[FvM]

TPIC6B596DW has open drain outputs, so the LED and common driver polarity has to be flipped.

For MOSFET gate driver, you have to check the switching delay made up by gate input capacitance and series resistor respectively driver output. I think it should work compared to the rather slow shift register update cycle.

 

[techy101]

After a bit of searching, and a Thanksgiving break, I'm back. I think I found a chip that will work, but wanted to run it by the folks on here.

I'd be replacing the 595 shift registers with the MIC5891
**broken link removed**