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need of help for designing 8x8 led matrix

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like that. only properly apply to the matrix polarity. There is another limitation. current through each output 0-63 FPGA, connected to a column of 1 ma - in this case the current through the output row will be 64 times more. It is necessary to put the power buffer/ or transistor for each of 8 row pins/
 

hi treqer,
I am using FPGA 64 Column Pin -- IC 573 buffer -- IC ULQ2803 -- 64 column leds
FPGA 8 row pin -- IC 573 Buffer -- IC ULQ2803 -- 8 row leds
I will check and let you know.

thanks,
V. Prakash
 

wrong. 2803 - the open collector key. it can be used on only one side of the matrix
 

hi treqer,

why we should not use 2803 on both rows and columns.? can you please explain?

Thanks,
V. Prakash
 

2805 is an 8 NPN transistors whose emitters are connected and have one pin. They can just short out its collector to the emitter when a voltage is applied to the input .. The emitter should be connected to the negative wire of the power supply. Between the positive wire of the source and collector sets the load.
 

hi treqer,

I will use both the 2803 with collector pulled up with resistor. will it be ok?
Regards,
V. Prakash
 

will not. from that which is connected to the cathodes of diodes this resistor is not needed. and that to the anodes of diodes - the brightness depends on the number of luminous diodes at the moment. 8 transistors to put laziness?
 

hi treqer,

In anode side, FPGA Pin --> IC 573 --> ULQ2803--> row leds
In cathode side, FPGA pin --> IC 573 ---> column leds.

will it be ok to have brightness? Please let me know.

thanks,
V. Prakash

---------- Post added at 12:21 ---------- Previous post was at 12:19 ----------

hi treqer,

In anode side, FPGA Pin --> IC 573 --> ULQ2803--> row leds
In cathode side, FPGA pin --> IC 573 ---> column leds.

will it be ok to have brightness? Please let me know.

thanks,
V. Prakash
 

wrong. 2803 can only be installed on the cathode side
 

hi treqer,

Can you explain why i have to use 2803 in cathode side only?

I am using 64x8 led matrix. Its column cathode and row anode.
64 columns and 8 rows. If i put 2803 in cathode, i have to use 8 individual numbers of 2803 to drive the 64 columns?
Instead we can use 2803 in anode rows?

Please explain why i have to use 2803 in cathode side?

Thanks,
V. Prakash
 

I already wrote about it. 2803 is a transistor switch, which closes at the negative power supply. load such a key can be activated only between him and the positive power supply. According to another no longer know how to say it. You can not turn. For switching the anode circuit of the transistor to use trailing anode to the positive power supply.

What the LEDs in the matrix and what their current glow?
 

hi treqer,

Thanks. It is an ordinary SRD LED. It has the Forward current of 10 mA.


Thanks,
V. Prakash
 

so would at once)))) 10x8 80 mA LED stand. is the maximum current column. current row - 64x80 = 5 amps. that is, to 8 pieces uln8003 (8 negative keys each). for them to connect the cathodes. and 8 positive power switch with a current of 5 amps. do not forget to limit the LED current.

this is the case if we want to get the brightness, as at 10 milliamperes. if both at 1-2 milliamps - easier. and absolutely different.
 

hi treqer,

thanks. As you suggest i will use 8 piece of IC in the column cathode. I will check and let you know.

thanks,
V. Prakash
 

hi treqer,

I had checked with 8x8 single Led matrix. It is working fine.

thanks,
V. Prakash
 

that checked? incorrect entry in 2803?
Try to light in the one column and next row all the diodes and compare the brightness
 

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