Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Power Distribution Switches, Load Drivers

STMicroelectronics ULN2001A

Name: ULN2001A
Brand: STMicroelectronics
SKU: ULN2001A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: ULN2001A

Manufacturer:: STMicroelectronics

Category:: Power Distribution Switches, Load Drivers

Package:: 16-DIP (0.300", 7.62mm)

Datasheet:: ULN2001A.pdf

Description:: IC PWR RELAY 7NPN 1:1 16DIP

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:3,459

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

ULN2001A from STMicroelectronics is a 7-channel high-voltage, high-current Darlington array IC with open-collector outputs, common-emitter configuration, integrated flyback diodes, 500 mA continuous per channel, and 50 V output voltage rating. It interfaces directly with DTL/TTL/PMOS/CMOS logic and drives inductive loads such as relays and solenoids in industrial control modules.

For engineers reviewing the ULN2001A datasheet, ULN2001A pinout, ULN2001A application, or ULN2001A equivalent, key selection criteria include per-channel current capability (500 mA), integrated clamping diode functionality, input compatibility across legacy logic families, and thermal resistance (R_thJA = 70 °C/W) in DIP-16 package.

Technical Context

The ULN2001A implements seven independent Darlington transistor pairs in a single monolithic chip, each with base resistors and emitter-connected common rail. Its architecture enables direct logic-level drive without external biasing components.

Each channel features an integrated 50 V, 350 mA-rated clamp diode for inductive load suppression, and supports paralleling of outputs to increase total current capacity. Input pins are arranged opposite output pins on the DIP-16 package to minimize PCB trace crosstalk and simplify routing.

Key Specifications

Parameter	Value and Actual Design Meaning
Output voltage	50 V - supports driving 24 V DC relays and solenoids with margin against inductive kickback
Continuous output current	500 mA per channel - sufficient for standard electromechanical relays and small DC motors
Peak output current	600 mA - allows short-duration surge handling during relay coil energization
Input compatibility	DTL/TTL/PMOS/CMOS - eliminates need for level-shifting circuitry in mixed-logic systems
V_CE(SAT)	1.1 V max at 200 mA - ensures low power dissipation and minimal voltage drop across active channel
R_thJA	70 °C/W (DIP-16) - defines maximum power budget (≈0.7 W at T_A = 85 °C) before thermal derating
Clamp diode reverse voltage	50 V - matches output voltage rating to safely absorb energy from inductive loads

Pinout & Package

ULN2001A is supplied in a 16-pin dual in-line package (DIP-16L) with copper leadframe for improved thermal performance. Pin layout places inputs (pins 1–7) on one side and corresponding open-collector outputs (pins 10–16) on the opposite side, enabling straight-through PCB routing.

Pin/Terminal	Circuit Role	Design Meaning
1–7	Input (base drive)	Logic-compatible inputs accepting TTL/DTL/PMOS/CMOS levels; internally biased with series resistors
8	Common emitter (GND)	Shared emitter connection for all Darlington pairs; must be tied to system ground
9	Common cathode (clamp diode)	Internally connects cathodes of all seven clamp diodes; requires external connection to load supply rail (e.g., +24 V)
10–16	Open-collector output	Seven independent collector outputs; each sinks current when driven high at corresponding input

Key Features

Feature	Design Value
Seven Darlington channels	Enables compact replacement of discrete driver arrays in multi-relay control panels
Integrated clamp diodes	Eliminates need for seven external flyback diodes, reducing BOM count and PCB area
Input-output pin opposition	Allows orthogonal PCB trace routing between microcontroller headers and relay terminals
Output paralleling support	Permits combining up to three channels for 1.5 A sink capability in high-power buffer applications
Copper leadframe DIP	Reduces thermal resistance by ≈15% vs. standard DIP, improving reliability under sustained load

Applications

Industrial Relay Control

Thermal Print Head Driver

Use Scenario: Driving 24 VDC electromechanical relays in PLC I/O modules and machine safety circuits.

IC Role / Device Role / Timing Role: High-side switch controller that sinks relay coil current through open-collector outputs with built-in transient suppression.

Use Value: Eliminates external diodes and reduces component count by 7× per module while maintaining 500 mA per channel reliability.

Use Scenario: Sequencing dot-matrix heating elements in receipt and label printers.

IC Role / Device Role / Timing Role: Current-sinking driver translating parallel data bus signals into localized thermal activation pulses.

Use Value: Matches thermal head's 350–500 mA per segment requirement and withstands repetitive 100 ms ON pulses without derating.

LED Filament Lamp Driver

DC Motor Direction Control (Half-H-Bridge)

Use Scenario: Switching incandescent-style LED arrays in signage and instrumentation backlighting.

IC Role / Device Role / Timing Role: Constant-current sink for resistive-inductive hybrid loads with slow turn-off decay.

Use Value: Clamp diodes suppress inrush-induced back-EMF spikes during rapid PWM dimming (≤1 kHz).

Use Scenario: Unidirectional DC motor control in automated valves and linear actuators.

IC Role / Device Role / Timing Role: Low-side driver stage paired with external high-side P-MOSFET or mechanical contact.

Use Value: Delivers 500 mA stall current with <1.3 V saturation drop, minimizing heat generation in compact enclosures.

Equivalent & Alternatives

The following parts are listed as comparable options for similar Darlington array applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
ULN2003A	Optimized for 5 V TTL/CMOS inputs (V_I(ON) ≤ 2.7 V); lower input threshold than ULN2001A (V_I(ON) ≤ 3 V)	Better suited for modern microcontrollers with 3.3 V or 5 V GPIO; less compatible with older PMOS/DTL logic	Select ULN2003A when interfacing with Arduino, STM32, or PIC MCUs; ULN2001A preferred for legacy industrial controllers
TD62003APG	Same 7-channel Darlington topology but with higher V_CE rating (100 V) and no integrated clamp diodes	Requires external diodes for inductive loads; used where higher voltage isolation or custom snubbing is needed	Choose TD62003APG only when operating above 50 V or requiring independent diode selection for EMI tuning

Compared with ULN2003A and TD62003APG, the ULN2001A uniquely balances broad logic-family compatibility, integrated protection, and thermal performance in DIP-16 - making it optimal for retrofitting legacy industrial controls without redesigning protection networks.

Availability

ULN2001A is available at Aetrix Electronics and suitable for industrial relay control, thermal print head driving, LED filament lamp switching, and DC motor actuation requiring stable component supply across long-lifecycle equipment programs.

Supply support for ULN2001A includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.

The ULN2001A belongs to ST's legacy high-voltage driver product line, engineered specifically for robust, low-cost interface between logic-level controllers and rugged electromagnetic loads in factory automation and building systems.

FAQ

Can ULN2001A drive a 12 V relay coil drawing 400 mA?

Yes. The ULN2001A is rated for 500 mA continuous per channel at 50 V, well above the 400 mA requirement. At 12 V supply, its typical V_CE(SAT) is 1.1 V, resulting in only 0.44 W power dissipation per channel - within safe thermal limits for DIP-16 at ambient temperatures up to 85 °C.

Is a pull-up resistor required on the output side?

Yes. Since ULN2001A outputs are open-collector, an external pull-up resistor (or load connected to positive supply) is mandatory to establish a defined high state when the Darlington is off. For relay coils, the coil itself serves as the pull-up load when connected between V_CC and the output pin.

What is the purpose of Pin 9 (common cathode)?

Pin 9 connects the cathodes of all seven internal clamp diodes. It must be wired to the same positive supply rail as the inductive load (e.g., +24 V), allowing stored magnetic energy to recirculate safely through the diode during turn-off - preventing voltage spikes exceeding 50 V at the collector.

How does ULN2001A differ from ULN2003A in practical use?

ULN2001A accepts higher input voltages (up to 30 V) and works with DTL, TTL, PMOS, and CMOS logic, whereas ULN2003A is optimized for 5 V TTL/CMOS with lower input thresholds. In practice, ULN2001A is preferred for mixed-voltage or legacy industrial systems; ULN2003A suits modern 3.3/5 V MCU designs.

ULN2001A Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Package/Case:: 16-DIP (0.300", 7.62mm)

Series:: ULx200xA

Packaging:: Tube

Product Status:: Active

Switch Type:: Relay, Solenoid Driver

Number of Outputs:: 7

Ratio - Input:Output:: 1:1

Output Configuration:: Low Side

Output Type:: NPN

Interface:: Parallel

Voltage - Load:: 50V (Max)

Voltage - Supply (Vcc/Vdd):: Not Required

Current - Output (Max):: 500mA

Rds On (Typ):: -

Input Type:: Inverting

Features:: -

Fault Protection:: -

Operating Temperature:: -40°C ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 16-DIP

ULN2001A FAQ

1.How can I place an order for ULN2001A through Aetrix?

Please submit a Request for Quotation (RFQ) for ULN2001A on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for ULN2001A reliable?

The price and inventory of ULN2001A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ULN2001A is usually 5 days.

3.What payment methods are accepted for ULN2001A?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ULN2001A transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for ULN2001A?

ULN2001A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your ULN2001A order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for ULN2001A?

For technical support, including ULN2001A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ULN2001A requirements.

6.How does Aetrix verify that ULN2001A is sourced from the original manufacturer or authorized distributors?

All ULN2001A products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ULN2001A meets industry standards.

7.What is the process for return or replacement of ULN2001A?

All ULN2001A units undergo pre-shipment inspection (PSI). If there is an issue with ULN2001A, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The ULN2001A part is unused and in its original packaging.

Return procedure for ULN2001A:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

Tech Hub

2026-09-03 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-01 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…

2026-08-21 What Is an LED Driver? Types, Circuits, Dimming, and Selection

An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…

2026-08-18 Operational Amplifier (Op Amp): Basics, Configurations, Feedback and Applications

Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…

2026-08-14 Jumper Cables: How to Use, Connect and Choose Them Safely

Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…