Texas Instruments ULN2004AINSR

Overview

ULN2004AINSR from Texas Instruments is a 7-channel high-voltage, high-current Darlington transistor array designed for driving inductive loads such as relays, lamps, and solenoids. Each channel delivers 500 mA collector current, supports 50 V output voltage, integrates input series resistors (10.5 kΩ), and features built-in common-cathode clamp diodes. It operates across −40°C to 105°C and interfaces directly with TTL/5-V CMOS logic.

For engineers reviewing the ULN2004AINSR datasheet, ULN2004AINSR pinout, ULN2004AINSR application, or ULN2004AINSR equivalent, this device is selected for robust load switching where integrated clamping, logic-level compatibility, and multi-channel consolidation reduce external component count in industrial control, appliance, and automation circuits.

Technical Context

The ULN2004AINSR implements seven independent NPN Darlington pairs, each with a dedicated 10.5 kΩ base resistor enabling direct TTL/CMOS drive without external biasing. Its internal clamp diodes are connected to a shared COM terminal, allowing simultaneous suppression of back-EMF from multiple inductive loads.

Each Darlington stage exhibits low saturation voltage (≤1.6 V at 350 mA input current), fast switching (tPLH/tPHL ≤10 µs over full temperature range), and high off-state input impedance - ensuring reliable turn-off even with floating logic inputs. The device's thermal design supports continuous operation at up to 105°C ambient when mounted on standard PCB layouts.

Key Specifications

Pinout & Package

SOP (NS) package: 16-pin surface-mount, 1.27 mm pitch, 10.4 mm × 5.3 mm body, 2.00 mm max height, RoHS-compliant, moisture sensitivity level 1 (260°C reflow).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ULN2004AINSR, ULN2003AIDR offers tighter input drive but reduced logic flexibility, while TD62003FG demands more board space and design effort - making ULN2004AINSR the preferred choice for new designs requiring plug-and-play integration, wide logic compatibility, and minimized external components.

Availability

ULN2004AINSR is available at Aetrix Electronics and suitable for industrial control systems, appliance manufacturing, and printer hardware development requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for ULN2004AINSR 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and connectivity technologies, with decades of experience in industrial-grade power interface solutions.

The ULN2004AINSR belongs to TI's ULN200x family of Darlington arrays, engineered specifically for ruggedized load switching in factory automation, home appliances, and office equipment where reliability, integration, and ease of use are critical.

FAQ

What is the maximum continuous current per channel for ULN2004AINSR?

The ULN2004AINSR is rated for 500 mA continuous collector current per Darlington channel under specified thermal conditions (TA ≤ 105°C, θJA = 64°C/W). Derating applies above 25°C ambient; full 500 mA is achievable with adequate PCB copper area or heatsinking. Peak pulsed current may exceed this value briefly, but sustained operation must respect the absolute maximum rating and thermal limits defined in the datasheet for ULN2004AINSR.

Does ULN2004AINSR require external flyback diodes when driving relays?

No - the ULN2004AINSR integrates seven common-cathode clamp diodes connected to pin 16 (COM). When COM is tied to the positive supply of the inductive load (e.g., relay coil), these diodes provide complete flyback protection. External diodes are unnecessary unless the load voltage exceeds 50 V or a custom clamping threshold is required - which would violate the absolute maximum ratings of ULN2004AINSR.

Can ULN2004AINSR be used with 3.3 V logic inputs?

Yes - the ULN2004AINSR's 10.5 kΩ input resistors allow reliable turn-on with 3.3 V CMOS outputs. At VI = 3.3 V, input current is ~0.31 mA, well above the minimum II(on) threshold (~250 µA) needed to saturate the Darlington pair. Verified operation across −40°C to 105°C confirms compatibility; no level-shifting circuitry is required for ULN2004AINSR in mixed-voltage systems.

What is the purpose of the COM pin (pin 16) on ULN2004AINSR?

Pin 16 (COM) is the common cathode connection for all seven internal clamp diodes. It must be connected to the positive supply rail of the inductive load (e.g., +12 V or +24 V) to enable flyback energy recirculation. Leaving COM unconnected disables clamping and risks destructive voltage spikes. This single-point connection simplifies layout and ensures coordinated protection across all channels of ULN2004AINSR.

How does ULN2004AINSR differ from ULN2003A in practical design?

The ULN2004AINSR uses a 10.5 kΩ input resistor on all seven channels, while ULN2003A has a 2.7 kΩ resistor on channels 2–7 and no resistor on channel 1. This makes ULN2004AINSR fully compatible with 3.3 V and 5 V logic without external components, whereas ULN2003A often requires external resistors for safe 3.3 V operation. Additionally, ULN2004AINSR's SOP-NS package offers better thermal performance and automated assembly compatibility than ULN2003A's legacy packages.