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[FAQ] ULN2803C: [ULN2803ADWR & ULN2803CDWR] Creating a common PCB footprint for 18-pin and 20-pin 8CH darlington transistor arrays devices

Part Number: ULN2803C

This post discusses how a 20-pin SOIC ULN2803CDWR can be footprint compatible with other 18-pin 8 channel Darlington transistor array devices with similar pinouts.


ULN2803CDWR is a 8-channel Darlington transistor array device which is available in a 20-pin SOIC package. This device pinout follows the same pin layout of 18-pin solutions except with the addition of two no connects at the bottom of the package. Below is a pinout comparison between a 18-pin, 8-CH Darlington transistor array and 20-pin, ULN2803CDWR device.



If 18-pin devices have a similar pinout to the ULN2803CDWR then a 20-pin SOIC PCB footprint can be used to allow the ULN2803CDWR to be used interchangeably with 18-pin solutions. See figure 2 below for an illustration of how a 20-pin PCB footprint can accommodate 18-pin and 20-pin solutions.



Please reference the actual datasheets for precise measurements to construct the PCB footprints.