STMicroelectronics E-ULN2004A

Overview

E-ULN2004A from STMicroelectronics is a 7-channel high-voltage, high-current Darlington array IC designed for interfacing microcontrollers and logic circuits to inductive loads. It features open-collector outputs rated at 500 mA continuous / 600 mA peak per channel, 50 V output voltage capability, integrated flyback diodes, and CMOS/PMOS-compatible inputs (6–15 V). It is commonly used to drive relays, solenoids, and thermal printheads in industrial control and automation systems.

For engineers reviewing the E-ULN2004A datasheet, E-ULN2004A pinout, E-ULN2004A application, or E-ULN2004A equivalent, this device serves as a robust, low-cost interface solution where logic-level signals must switch moderate-power inductive loads with built-in transient protection and layout-optimized pin arrangement.

Technical Context

The E-ULN2004A integrates seven independent Darlington transistor pairs with common-emitter configuration and on-chip clamp diodes connected from each collector to the common cathode pin (pin 9). Each channel operates as a saturated-switching stage with TTL/CMOS-compatible input thresholds optimized for 6–15 V logic families.

Its input pins (1–7) are positioned opposite output pins (10–16) on the DIP-16 package to minimize PCB trace crossovers. Thermal performance is enhanced by a copper leadframe, yielding R_thJA = 70 °C/W in DIP-16L - enabling reliable operation up to 85 °C ambient with appropriate derating.

Key Specifications

Pinout & Package

Package: 16-pin Dual In-line Package (DIP-16L) with copper leadframe for improved thermal performance. Pin pitch: 2.54 mm. Body width: 7.62 mm. Total length: ~19.3 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ULN2003A, E-ULN2004A offers higher noise immunity and broader logic compatibility; versus TBD62083AFG, it trades slightly higher saturation voltage for complete inductive-load protection without external components.

Availability

E-ULN2004A is available at Aetrix Electronics and suitable for industrial relay control, thermal printhead driving, solenoid valve actuation, and LED matrix applications requiring stable component supply across long-lifecycle embedded programs.

Supply support for E-ULN2004A 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 product portfolios.

The ULN200x series belongs to ST's legacy high-voltage interface product line, engineered specifically for robust, cost-effective bridging between digital logic and medium-power inductive or resistive loads in harsh industrial environments.

FAQ

Can E-ULN2004A drive a 24 V solenoid drawing 450 mA?

Yes. The E-ULN2004A is rated for 500 mA continuous per channel and 50 V output voltage, making it suitable for 24 V solenoids up to 450 mA. Ensure the COM pin (9) is connected to the 24 V supply rail to activate the internal clamp diode, and verify ambient temperature stays ≤85 °C with appropriate PCB copper area for heat dissipation.

Is pin 9 (COM) required to be connected for inductive loads?

Yes. Pin 9 must be connected to the positive side of the inductive load supply (e.g., +24 V) to provide a return path for flyback current through the internal clamp diodes. Leaving it unconnected disables transient suppression and risks voltage overshoot exceeding 50 V, potentially damaging the IC or upstream circuitry.

What is the maximum number of outputs that can be paralleled safely?

Up to two adjacent outputs (e.g., OUT1 + OUT2) may be paralleled to achieve 1 A total current, provided traces and layout support equal current sharing. Paralleling more than two channels is not recommended due to mismatched V_CE(SAT) and thermal imbalance, which can cause premature failure of the lowest-drop channel.

Does E-ULN2004A require external base resistors on input pins?

No. The E-ULN2004A includes internal base resistors (≈2.7 kΩ typical) sized for direct connection to 6–15 V CMOS/PMOS logic sources. External resistors are unnecessary unless signal integrity concerns (e.g., long traces, EMI) warrant added filtering or current limiting beyond datasheet-specified II(ON) values.