ULN2800

The ULN2800 is a high-voltage, high-current Darlington transistor array that is part of the ULN2000 family of driver ICs. It provides multiple NPN Darlington pairs in a single package, with inputs that include built-in base resistors and outputs configured as open collectors. When a digital control signal is applied to an input, the corresponding Darlington pair conducts and sinks current from the associated load to ground.

The device is commonly used as a low-side switch to drive inductive and resistive loads, such as relays, lamps, motors, solenoids, LEDs, and similar actuators, from a logic-level controller. The open-collector outputs allow multiple loads to be wired independently to a common supply without requiring separate driving transistors for each load.

Protection features typically include diodes for inductive kickback, which can be connected to a COM pin or supply rail depending on the exact variant. This flyback protection helps safeguard the device and the driving circuitry when handling inductive loads. The ULN2800 is designed for TTL/CMOS logic level inputs and provides integrated current-limiting resistors on the inputs, simplifying interfacing with microcontrollers and other controllers.

Electrical ratings vary by specific part revision and package, but the ULN2000 family generally supports per-channel voltages in the tens of volts range and currents in the hundreds of milliamps. Designers should consult the exact datasheet for the ULN2800 variant they are using to confirm maximum voltage, current, and thermal limits.

See also: ULN2000 family, ULN2803 (an eight-channel variant with similar purpose), flyback protection in inductive loads.