Does an Arduino Mega able to power 13 74HC595 shift registers and 104 LEDs?

Using Arduino LEDs and Multiplexing
1

Hi,

I am about to use an Arduino Mega to control 13 shift registers (74HC595) which in turn control 104 LEDs. Does Arduino Mega connected to a DC going to have enough power for those 104 LEDs? If not what should I supply extra power to those LEDs?

2

Not including the LED's, you are at nearly 1 AMP with 13 74HCT595's when drawing typical package current. This would already exceed USB available current and tax the onboard power regulator supply using a DC plug power source (rated at 800ma) so thermal shut down is likely before LEDS are added . When you add the LED's... no chance... that is at LEAST another Ampere or more. You will need a totally external regulated power source with 5V rated at 3 amps to be safe.

595 worst case current each 70mA = 910mA

LED's @ 10mA current limit = 1040mA

3

Thanks for the reply. :slight_smile: How do I setup an external regulated power source as exactly what you said? What extra components am I going to need for this? Can you shed some more light?

Thanks a lot! :slight_smile:

4

Can you shed some more light?

Mwahahaha :smiley:

Maybe use something that drives a few more LEDs to start with (like an M5451 chip or similar - drives 35 LEDs per chip)

Mowcius

5

Does Arduino Mega connected to a DC going to have enough power for those 104 LEDs

It also depends on how long you keep those LEDs on. There are LED shields out there with 256 LEDs and they are powered from arduino.

6

Get yourself a wallwart.
I use this one a lot
http://www.mpja.com/prodinfo.asp?number=18520+PS

7

mowcius:
Mwahahaha :smiley:

Maybe use something that drives a few more LEDs to start with (like an M5451 chip or similar - drives 35 LEDs per chip)

Mowcius

I am new to this M5451 chip and it's interesting. If I were going to use it, I am going to need 3 M5451 chips right?

florinc:
It also depends on how long you keep those LEDs on. There are LED shields out there with 256 LEDs and they are powered from arduino.

I am going to be able to control every single LEDs, their on and off time. This is like a running LEDs except that the delay between each lighted up LEDs would be different. Some would have 3 secs and some shorter. At the end, all LEDs would light up and stay for half an hour maybe.

CrossRoads:
Get yourself a wallwart.
I use this one a lot
5V 4A Power Adapter OPENPEAK OP-20004

So I can use this adapter to connect directly to the shift registers?

8

Yes, the wallwart will provide 5V to the shift register power pins. Can use it to provide 5V to the Arduino as well, connect to the 5V pin and bypass the Vin/Voltage regulator circuit.

9

M5451 35-bit shift register with 15mA-25mA SINK current (must pull cathodes low to turn on LEDs).

10

CrossRoads:
Yes, the wallwart will provide 5V to the shift register power pins. Can use it to provide 5V to the Arduino as well, connect to the 5V pin and bypass the Vin/Voltage regulator circuit.

CrossRoads:
ST Microelectronics 0zqj6og5wcoq8y1zyxt7r79056py datasheet pdf

M5451 35-bit shift register with 15mA-25mA SINK current (must pull cathodes low to turn on LEDs).

Thanks a lot for these information! :slight_smile: I'll give the datasheet a read.

11

I am new to this M5451 chip and it's interesting. If I were going to use it, I am going to need 3 M5451 chips right?

Yeah you'd only need 3 of them :slight_smile:

There are no doubt other chips around too - that's just the only one I can think of off hand which drives so many LEDs.

12

Another way is to use a MAX 6953. It will drive 140 LEDs.
You'll have to read the datasheet at www.maxim-ic.com and see if the 140 LEDs can be addressed individually.
It worked nicely for me driving four 5x7 matrix displays.
40 pin DIP easy to work with on a breadboard too.

13

and see if the 140 LEDs can be addressed individually.

Well if they can be addressed in a matrix - you can address them like that to make them light up individually. Might make wiring a bit of a pain if the LEDs aren't close together though.

Neat chip - I'll have to remember that one.

14

Its made for led matrix, so you cant address each led individually, I have some of those around here and they are only usefull for the 5x7 led matrix, otherwise they dont serve to nothing.

15

They have a lot of characters defined in a lookup table kind of thing, with space to add 24 more.

So maybe the MAX7221 or 7219 with its ability to drive an 8x8 matrix (64 LEDs) would be better, operated in No-Decode mode.

Need 2 of them.