Help in Darlington Array ULN2003A

[btminzon]

darlington array circuit

Hi ,

I need to amplifi my input current from 25mA to 100mA, and i willl use this chip... How can i use it? need an extra resistor or circuit? i never worked with darlignton array...thanks folks!!

 

[snake]

darlington array circuits

Hi,

The only diference about a single darlington transistor and an array is that you have to respect de total power dissipation on that device, these chip is normaly use as a switch and not as an amplifier, but whit small power you can use it too.

rgs

 

[powergood]

darlington array pull up

hi,

yes.
you can use it.

you dont need any resistors. only the ULN.

[]'s

 

[btminzon]

darlington array ground common

so, i don't need to polarize, like a emitter folower, comom-base, etc? tnx again

 

[powergood]

darlington array

No. Inside of the chip you have some resistors that makes the polarization.

But, for safety, you can use a resistor for power dissipation. Thus, you put a resistor serially with the ULN2003A emitter (output).


look at ULN2003A datasheet for more information.

ok?

[]'s

 

[Kral]

how to connect a darlington array

btminzon,
You can download the SGS-Thompson data sheet from:
~ http://www.datasheetcatalog.com/datasheets_pdf/U/L/N/2/ULN2003A.shtml
This datasheet has shematics of the Darlington stages. This device is intended for use as a high power logic inverter. In other words, it turns "ON" when the inpute voltage exceeds the "1" voltage threshold of the device. Since the Dalingtons stages shar a common ground, and the base connections are not available, it would be very difficult to use this device in a linear application, since it would be nearly impossible to achieve a stable bias point.
Regards,
Kral

 

[funster]

you can only connect the circuit's input and output as well as power supply,

it will work normally.


best regards

Hi ,

I need to amplifi my input current from 25mA to 100mA, and i willl use this chip... How can i use it? need an extra resistor or circuit? i never worked with darlignton array...thanks folks!!

 

[samy alex]

Hi
Injecting 25 ma in the base of uln200X will saturate it so you will use it as a switch only in your application if so you have to use a pull up resistor equal to Vcc divided by 0.1 amp and the resulting value will be the resistor value in Ω .

 

[m_kavith]

plz anyone help me. i created library file in orcad capture for uln2003. if i started pcb design in layout it shows error there is no 9th pin plz create it but i create 9thpin (com pin) & connect to vcc +5v. it shows error again & again what can i do?

 

[betwixt]

The best thing to do is go back to the theory books, As Kral has pointed out, this is not a device to be used in a linear application, it is intended as a ground side power switch. The 'COM' pin is the common junction of internal diodes, intended to clamp the 'kick back' from switching inductive loads off. It will do nothing at all if you attempt to use the IC in a linear mode but if you connect it to less than your supply voltage it will cause unexpected output voltages. The 'GND' pin is the common emitter connection of all the internal transistors and bias networks, you can not use it as an output, at least with predictable results. Suggesting you inject 25mA into the base (input) pin is also ridiculous as it would need more than 68V at the pin to make that much current flow, it is voltage driven, not current driven and the voltage to reach saturation is less than 5V.
If you are really looking for a current amplifier, consider just a single bipolar transistor, you are only asking for a gain of 4 so it isn't complicated.

Brian.