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Two green ULN2803A driver modules with pin headers

Universal

Universal ULN2803A Transistor Array Driver Module 2 Pcs

SKU CH-PKYJ-589M7

Eight-channel driver module handles 500 mA per channel at 50 V with built-in clamp diodes for inductive loads

  • Eight high-voltage outputs drive relays and motors directly
  • 500 mA per channel with built-in clamp diodes for inductive loads
  • 7 kΩ base resistors allow direct TTL and 5 V CMOS control
  • Two modules included for multi-channel or parallel current expansion
  • Rated from -65 °C to 150 °C junction temperature for harsh environments

ULN2803A Transistor Array Driver Module

The Universal ULN2803A is a high-current driver module supplied as a pair of boards. Each module contains eight NPN Darlington pairs rated for 50 V and 500 mA per channel with built-in clamp diodes for inductive load protection. The 2.7 kΩ base resistors allow direct operation from TTL or 5 V CMOS logic levels.

Hobbyists and engineers driving relays.

Makers building Arduino, PLC or custom relay boards will find the eight-channel layout convenient for parallel connection when more current is needed. The modules are not suited for loads exceeding 500 mA per channel or voltages above 50 V, so builders needing higher power switching should look at alternative driver topologies.

Sustained operation within thermal limits

Each Darlington pair dissipates heat proportional to collector current and saturation voltage, so continuous 500 mA loads will raise junction temperature toward the 150 °C maximum. Adequate PCB copper or external heatsinking becomes necessary for long-duration runs, while short pulsed loads stay well within the -65 °C to 150 °C junction and storage range.

Highlights

  • Eight high-voltage outputs drive relays and motors directly
  • 500 mA per channel with built-in clamp diodes for inductive loads
  • 7 kΩ base resistors allow direct TTL and 5 V CMOS control
  • Two modules included for multi-channel or parallel current expansion
  • Rated from -65 °C to 150 °C junction temperature for harsh environments

Specifications

No published specifications for this item yet.

Questions about this item

What input voltage does the ULN2803A module need to drive the eight NPN pairs?

The module works directly with TTL or 5 V CMOS logic levels; the input voltage rating is DC 30 V and each pair has a 2.7 k series base resistor for direct connection.

Can the ULN2803A module share a load with an older relay board that uses 50 V coils?

Yes — each output handles 50 V collector-emitter voltage and 500 mA peak current, and the built-in clamp diodes protect both boards when switching inductive loads.

How do I confirm the ULN2803A module is switching correctly after wiring it?

Measure the collector voltage drop when the input goes high; it should fall to saturation level while the clamp diodes keep the output within the 50 V, 500 mA ratings.

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