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PROJECT BASICS
POWER SUPPLY
SENSORS
RELAY
CURRENT BUFFER
WHERE & HOW to USE
HOW it WORKS
BIDIRECTIONAL CURRENT BUFFER
PARALLEL PORT
LEVEL SHIFTER
WIRELESS COMMUNICATION
PROJECT IDEAS
 

 

 

Current Buffer –

The ULN2001A, ULN2002A, ULN2003 and ULN2004A are high voltage, high current darlington PIN CONNECTION arrays each containing seven open collector dar- lington pairs with common emitters. Each channel rated at 500mA and can withstand peak currents of 600ma.

WHERE TO USE:

These versatile devices are useful for driving a wide range of loads including solenoids, relays DC motors, LED displays filament lamps, thermal print- heads and high power buffers in the situations when the input signal is not providing enough currents. E.g. we need to drive a relay or DC motor according to the signal given by some IC.

HOW TO USE:

Suppose we need to drive DC motor and the motor needs a specific amount of current. It’s in the range of 30-100 mA. But such high currents cannot be delivered by simple ICs or parallel port etc. Hence we need a current buffer for that. So we select Uln-2003 in this case.

The pin connection of ULN 2003 is as follow:

The ULN 2003 is an inversion buffer and hence output is taken from pin 9 and the output pin.

If we are driving motor according to the signal from some IC which is not able to provide enough current, then

  • Firstly we input that signal to one of the 7 input pins of ULN 2003, say pin 1.
  • Then output I taken from the Pin 9 and the corresponding output pin i.e. pin 16 as shown below:

    • We also connect a high current power source of appropriate voltage between pin 9 and pin 8.

     

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