Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

How to use ULN2003 darlington array?

Status
Not open for further replies.
N

neoaspilet11

Full Member level 5
Full Member level 5
Joined
Sep 29, 2005
Messages
277
Helped
29
Reputation
56
Reaction score
8
Trophy points
1,298
Location
Cebu, Philippines
Activity points
4,048
darlington array

Any idea on this using LED or LAMPS as loads and inputs coming from microcontroller?


Or can I directly connect the Microcontroller pins to the input to of the ULN2003/2004 darlingtonchip?


Thanks,
neo
 

uln2003

LEDs (not lamps) can be driven directly from most microcontrollers ..

If you want to drive lamps, ralays, etc. using darlington arrays, pins (ULN2003 pins 1-7) can be directly connected to a microcontroller (see attached picture), although some microcontrollers may require 1-10kΩ pullup resistors - refer to a particular part data sheet ..

Regards,
IanP
 
how to use uln2003

You don't need to worry about this COMMON (pin9) if you drive LEDs (in general - non-inductive lods) ..
If you drive relays the common pin(9) should be connected to +V (not GND!!!) .. see attached picture ..

Regads,
IanP
 

Attachments

  • uln2003_microcontroller_rlys_1471.png
    uln2003_microcontroller_rlys_1471.png
    13.6 KB · Views: 424
darlington array wiki

245 is rather BUS-to-BUS buffer, it is like normal 3-state gates connected back-to-back ..
Much better option would be to use 74(XX)05,06 or 07 which are OC buffer/driver gates ..
In other words, driving LEDs through 245's would be more-the-less the same as connecting them directly to microcontroller ..

Regards,
IanP
 
using uln2003

Actually I was looking for 2 X 8 - output sourcing LED IC driver. because most LEDs need at most 20mA to lit brightly, directly connecting to microcontroller wont do it because, there will be much current will be drawn from the IO pins.

The 74XX05, 06 07 rather come in 6 hex buffer which would consume much of board space. 16 LED source drivers need 3 chips

And also the ULN2003 pins is rather short just 7 sink pins; need 8 LED source outputs per IC

Any ideas on this?
 

uln2003 usage

There are 8-bit drivers => UDN2981 ..
**broken link removed**
The difference is that they are "high-side" drivers, so loads are connected between outputs and GND ..

Other option => 16 x el-cheapo 2N7000 MOSFETs (no gate resistors required) ..

Regards,
IanP
 

pic uln2003

Tnx for the info Ian P.

However this rather complicate my options:

1.) 16 Mosfets equals 16*3 pins, traces and foot prints. This will really push the board designer to the edge. Plus the Micro lines.

2.) The UDN2981 has separate load ground and logic grounds. hmm I wonder if this an issue particularly that the application is multiplexed led display where the columns are driven by cascaded sink shift register drivers and Im still looking for the ROW source drivers
 

darlington led driver

hello to alll

i am trying build led moving messae 8x40 using pic16f877a and 74hc595+uln2003a

what my question is i want to the rows to be positive and cols be negative

how can i use uln2003a

i will use tr for rows like 2sa18015 and for cols shift register 74hc595 so i want to attach uln2003a or uln2803a as this is darlington array for the brightness

can any bedy help me how to do this

thanks
 

uln2003 pic

Hello World...

Recently I have got some ULN2003 but I need to drive a RGB LED that has a common cathode. :(

I know ULN2981 can do the job, but I don't have any....

Any suggestions?

Added after 37 minutes:

Humm.. How about if I use a negative voltage source? Would that work? Just slightly confuse how to supply +V to my microcontroller now..
 

uln2003 how to use

No help?

Humm.. anyways I have done some digging around, maybe I will use a P-ch MOSFET (IRF9520) to drive 50 LEDs (20mA each) in parallel

i.e. I will use 3 IRF9520 to drive 3 channels (R, G & B)

Now if the LEDs are good (i.e. the fwdV are pretty much the same) and I want to be cheap, I guess I can even stick with 1 resister per channel instead of 150 resisters (3 vs 150!)

Am I going to blow something up?
 

use of uln2003

Still no help eh...

Oh well, I guess I am on my own on this one... if my caclulation is correct, to drive 50 RGB LEDs at MAX, I will need a 3.3W (yes Watt!) resistor and 2 1.8W...

Given I don't have much experience on MOSFET, and the only way to learn I guess is to fry some... With IRF9520, I think I can do 1A (50 x 20mA) without any problems.

Some specs.
Supply Voltage: 5V
V(fwd-Red) 2V
V(fwd-G & B) 3.4V
If 20mA

Will be using a PIC to do PWM to change color. So in theory, at no time all 3 color will be on, i.e. under 3A.

Most I will do is mixing 2 colors, so 2A max is more likely.

I am still debating if I should use 3 resistor for each channel, or total of 150 resistors (3 per LED) or group them in to 5 LEDs per group and use 15 resistors...

p.s. How much voltage drop is across Source and Drain on a p-ch MOSFET? With 0.6ohm, I just want to calculate how much power dissipation I am dealing with. i.e. if heatsink is required.
 

uln2003 cathode common

yes you can use uln2003 ic with microprocessor i see interface with d78f0034bgc it is an n.e.c microprocessor.[/GVideo][/youtube]
 

the first time that contact the darlington array thank u so much
 

Re: uln2003

IanP said:
LEDs (not lamps) can be driven directly from most microcontrollers ..

If you want to drive lamps, ralays, etc. using darlington arrays, pins (ULN2003 pins 1-7) can be directly connected to a microcontroller (see attached picture), although some microcontrollers may require 1-10kΩ pullup resistors - refer to a particular part data sheet ..

Regards,
IanP
Click to expand...

can u tell me how to drive a 12v relay using uln2003 or 2004
 

Actually I was looking for 2 X 8 - output sourcing LED IC driver. because most LEDs need at most 20mA to lit brightly, directly connecting to microcontroller wont do it because, there will be much current will be drawn from the IO pins.

**broken link removed**
 

HIE can any one tel me how much current is required to drive relays like LEONE SC5-12V DC using ULN2003A? MENS HOW MUCH CURRENT IS REQUIRED TO DRIVE LEONE SC5-12V DC RELAYS?
 

Find the data sheet for the relay, it will tell you the coil resistance.

The current is calculated by the voltage (12V in this case) divided by the coil resistance. I think the SC5-12 has a coil resistance of 400Ω but it isn't listed in their catalog any longer so please confirm this with a test meter. If it is 400Ω, the current will be 12/400 Amps or 30mA.

Brian.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top