Standard Circuits 2 - Using a Darlington Driver IC
If a number of output devices are being controlled it may be necessary to use a
number of output transistors. In this case it will often be more convenient to use a
ULN2003 Darlington driver IC. This is simply a 16 pin ‘chip’ that contains 7
darlington transistors similar in value to the BCX38B. The ‘chip’ also contains internal
back emf suppression diodes and so no external 1N4001 diodes are required.
A device called the ULN2803 Darlington Driver IC is also available. This is identical to
the ULN2003 except that it is an 18 pin device and contains 8 darlington pairs instead
of 7. If it is necessary to pass relatively high currents through a device it can be useful
to ‘pair up’ drivers as shown with this circuit.
A ULN2803 darlington driver is supplied prefitted to the PICAXE interface board.
If a number of output devices are being controlled it may be necessary to use a
number of output transistors. In this case it will often be more convenient to use a
ULN2003 Darlington driver IC. This is simply a 16 pin ‘chip’ that contains 7
darlington transistors similar in value to the BCX38B. The ‘chip’ also contains internal
back emf suppression diodes and so no external 1N4001 diodes are required.
A device called the ULN2803 Darlington Driver IC is also available. This is identical to
the ULN2003 except that it is an 18 pin device and contains 8 darlington pairs instead
of 7. If it is necessary to pass relatively high currents through a device it can be useful
to ‘pair up’ drivers as shown with this circuit.
A ULN2803 darlington driver is supplied prefitted to the PICAXE interface board.
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