Skip to main content
Log in
STMicroelectronics ULN2068B — Discrete Semiconductors

STMicroelectronics ULN2068B Quad NPN Darlington

MPNULN2068B
Active

STMicroelectronics ULN2068B, Quad NPN Darlington array, 50 V Vceo, 1.75 A Ic per channel, 1.4 V Vce(sat) at 2 mA Ib, 1.25 A Ic, 16-PowerDIP through-hole package, -20°C to 85°C operating temperature.

$6.8000Ref. price · indicative, final on quote
STMicroelectronics ULN2068B datasheet (PDF)
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

ULN2068B specifications
ParameterValue
MountingThrough Hole
FET type4 NPN Darlington (Quad)
Voltage - collector emitter breakdown50V
Current - collector (Ic)1.75A
Power - max1W
Operating temperature-20°C~85°C(TA)
PackageTube
Case16-PowerDIP (0.300\", 7.62mm)
Vce saturation (Max) @ ib, ic1.4V @ 2mA, 1.25A

Product details

Quad Darlington array for medium-current switched loads

The STMicroelectronics ULN2068B integrates four NPN Darlington pairs in a single 16-PowerDIP through-hole package, each rated for a continuous collector current of 1.75 A and a collector-emitter breakdown voltage of 50 V. Each channel includes the base resistor and a clamp diode for inductive flyback, so a relay, solenoid, or stepper-motor winding connects directly between the output and the supply rail without an external catch diode. The 1.4 V maximum saturation voltage at 1.25 A (2 mA base drive) sets the per-channel conduction loss — at full load that is about 2.2 W total across four channels, which the PowerDIP's leadframe and the PCB copper must sink.

1.75 A per channel — where the current rating lands

The 1.75 A maximum collector current per Darlington is the absolute ceiling at 25°C case temperature; the practical continuous current in a 85°C ambient, still-air environment is lower because the 1 W package power limit and the junction-to-ambient thermal path through the 16 leads set the real derating. For a 12 V relay bank pulling 500 mA per coil, the ULN2068B runs with 2.8 V of headroom and about 0.7 W total dissipation — well within the thermal budget. For a 24 V solenoid at 1.2 A, the 1.4 V saturation drop leaves 22.6 V across the load and dissipates 1.68 W per channel, which requires airflow or a heatsink on the PowerDIP body.

Through-hole PowerDIP — board integration note

The 16-PowerDIP (0.300-inch row spacing, 7.62 mm body width) is a through-hole package intended for wave-solder assembly or manual insertion in prototype runs. The 20 mm × 7.10 mm body has staggered lead exits that increase the copper cross-section from the die to the PCB pad, improving thermal conduction compared to a standard DIP-16. For best thermal performance, connect all GND pins (pins 9 and 10) to a continuous ground plane with wide traces, and avoid routing sensitive analog signals under the package — the Darlington outputs switch inductive loads and couple switching noise into the substrate.

The base product number ULN2068 covers the full family including the A and B suffix variants.

Frequently asked questions

Is ULN2068B a direct replacement for ULN2003?

No. The ULN2003 is a 500 mA per-channel Darlington array in a DIP-16 or SO-16 package. The ULN2068B is rated for 1.75 A per channel — 3.5× the current capability — and uses the 16-PowerDIP package with a different leadframe and thermal path. The pinout is the same (1–7 inputs, 8 GND, 9 COM, 10–16 outputs), so it is pin-compatible on the board, but the higher saturation voltage and power dissipation mean the PCB copper and enclosure ventilation must be sized for the ULN2068B's thermal load. For a 500 mA relay bank originally designed around a ULN2003, the ULN2068B will work with no circuit chan

What is the maximum collector current of ULN2068B?

1.75 A per channel, continuous, at 25°C. The practical limit in a 85°C ambient depends on how many channels are on simultaneously and the PCB's ability to sink the 1 W package power limit. For all four channels conducting 1.75 A each, the total dissipation would exceed 9 W — far above the package rating — so the per-channel current must be derated when multiple outputs are active.

Are ULN2068A and ULN2068B interchangeable?

Yes, they are the same silicon in the same 16-PowerDIP package. The A and B suffixes typically indicate a minor test-limit or temperature-range variation, but both carry the same 1.75 A collector current rating and 50 V breakdown voltage. The ULN2068B is the current-production variant; the ULN2068A may appear in older stock or surplus channels. Confirm the operating temperature range on the specific date code if substituting.