STMicroelectronics ULN2003D1

Overview

ULN2003D1 from STMicroelectronics is a 7-channel high-voltage, high-current Darlington array IC designed for interfacing low-voltage logic (5V TTL/CMOS) to inductive loads. Each channel delivers 500mA continuous output current (600mA peak), supports 50V output voltage, and integrates clamp diodes for relay/solenoid suppression. It is widely used in industrial control modules driving relays and stepper motor windings.

For engineers reviewing the ULN2003D1 datasheet, ULN2003D1 pinout, ULN2003D1 application, or ULN2003D1 equivalent, key selection criteria include per-channel saturation voltage (≤1.3V at 200mA), input compatibility with 5V logic families, thermal resistance (120°C/W in SO-16), and integrated flyback diode functionality-critical for relay driver reliability and PCB layout simplification.

Technical Context

The ULN2003D1 implements seven independent NPN Darlington pairs with common-emitter outputs and on-chip freewheeling diodes connected from each collector to the common cathode pin (pin 9). Its input stage is optimized for 5V TTL/CMOS logic levels, with VI(ON) ≤2.7V and II(ON) ≈0.93–1.35mA at 3.85V.

Each Darlington pair provides DC current gain ≥1000 at IC = 350mA, VCE = 2V, enabling direct drive from microcontroller GPIOs without external base resistors. The SO-16 package supports surface-mount assembly and offers 120°C/W junction-to-ambient thermal resistance, limiting maximum continuous power dissipation to ~416mW per channel at TA = 85°C.

Key Specifications

Pinout & Package

ULN2003D1 is housed in a 16-pin narrow SOIC (SO-16) package with 1.27mm pitch, RoHS-compliant and ECOPACK® certified. Pin numbering follows standard SOIC top-view convention with pin 1 marked by a beveled corner.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TBD7200A and ULN2803AD1, ULN2003D1 offers optimal balance of channel density, integrated protection, and 5V logic compatibility for cost-sensitive 7-output relay/solenoid interfaces-whereas TBD7200A trades integration for higher current, and ULN2803AD1 extends channel count at the expense of pinout rework.

Availability

ULN2003D1 is available at Aetrix Electronics and suitable for industrial automation, printer subsystems, and embedded control systems requiring stable component supply and long-term manufacturability.

Supply support for ULN2003D1 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, specializing in automotive, industrial, and power management ICs with strong analog and discrete portfolio depth.

The ULN200x series belongs to ST's legacy high-voltage interface product line, engineered specifically for robust, low-cost driving of electromechanical loads in harsh industrial environments.

FAQ

What is the maximum safe operating temperature for ULN2003D1?

The ULN2003D1 has a maximum junction temperature (T_J) of 150°C and operates over −20°C to +85°C ambient. With R_thJA = 120°C/W in SO-16, sustained power dissipation above ~416mW per channel at 85°C ambient risks exceeding T_J; derating is required for multi-channel simultaneous operation.

Can ULN2003D1 outputs be paralleled for higher current?

Yes-ST explicitly states outputs can be paralleled to increase current capacity. When two channels are paralleled, total continuous current rises to 1A (2 × 500mA), provided V_CE(SAT) mismatch is minimized and thermal design accounts for combined power dissipation.

Is a current-limiting resistor required on the input pins?

No-ULN2003D1 inputs are internally biased and compatible with 5V TTL/CMOS logic. Input current is self-limiting (~0.93–1.35mA at 3.85V), so no external series resistor is needed for standard microcontroller GPIO drive.

How should the COM pin (pin 9) be connected?

Pin 9 (COM) must be connected directly to the positive supply rail of the inductive load (e.g., +12V or +24V). This ties the cathodes of all internal clamp diodes to that rail, allowing flyback current to recirculate safely through the load supply instead of damaging the IC or upstream circuitry.