Texas Instruments ULN2003BDR

Overview

ULN2003BDR from Texas Instruments is a 7-channel high-voltage, high-current Darlington transistor array designed for logic-level interfacing to inductive and resistive loads. It delivers 500 mA per channel, supports up to 50 V output voltage, integrates input base resistors (2.7 kΩ) and common-cathode clamp diodes, and operates across –40°C to +105°C - widely used in relay driver circuits for industrial PLC I/O modules.

For engineers reviewing the ULN2003BDR datasheet, ULN2003BDR pinout, ULN2003BDR application, or ULN2003BDR equivalent, key selection criteria include per-channel saturation voltage (≤1.6 V at 350 mA), collector cutoff current (≤20 μA), input compatibility with TTL/CMOS, thermal derating behavior, and COM pin configuration for flyback protection in solenoid control.

Technical Context

The ULN2003BDR implements seven independent NPN Darlington pairs with integrated 2.7-kΩ series base resistors enabling direct drive from 3.3 V or 5 V logic. Each channel features open-collector outputs and shares a common emitter (E) and common cathode clamp node (COM), allowing simultaneous suppression of inductive kickback across all channels when COM is tied to the load supply rail.

Its functional architecture relies on cascaded gain stages: input current flows through the base resistor into the pre-driver emitter, then into the main Darlington's base, delivering high DC current gain (hFE > 1000 at 100 mA). Switching is unidirectional (sink-only), with propagation delays under 10 μs over full temperature range and no internal pull-ups - requiring external pull-up resistors for resistive load logic-high generation.

Key Specifications

Pinout & Package

ULN2003BDR is supplied in a 16-pin SOIC (D) package measuring 9.90 mm × 3.91 mm, with gull-wing leads and standard JEDEC MS-012AC footprint. The package supports surface-mount reflow assembly and provides adequate thermal dissipation (R_θJA = 81.2°C/W) for moderate-duty cycling.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ULN2003AD and TD62003FG, ULN2003BDR offers the lowest leakage for fail-safe hold states and widest voltage margin for 48 V inductive loads, making it optimal for new industrial control designs requiring long-term reliability and wide supply tolerance.

Availability

ULN2003BDR is available at Aetrix Electronics and suitable for industrial PLC I/O modules, HVAC actuator controllers, and automated test equipment requiring stable component supply and long-lifecycle support.

Supply support for ULN2003BDR 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 focused on analog, embedded processing, and connectivity technologies, serving industrial, automotive, and communications markets with high-reliability components.

The ULN2003BDR belongs to TI's legacy interface IC portfolio, engineered specifically for robust logic-to-high-power bridging in harsh environments - emphasizing ESD resilience, wide temperature operation, and integrated protection for electromechanical load control.

FAQ

What is the maximum safe operating voltage on the COM pin of the ULN2003BDR?

The COM pin of the ULN2003BDR must not exceed 50 V, as this is the rated reverse voltage of the internal clamp diodes. Exceeding 50 V risks permanent diode breakdown and device failure. In practice, TI recommends limiting COM to ≤48 V for 24 V industrial systems with safety margin, and always ensuring that output voltage (V_CE) never exceeds COM voltage to prevent forward-biasing the diodes and causing excessive current into the COM node.

Can multiple channels of the ULN2003BDR be paralleled to increase current capacity?

Yes, multiple channels of the ULN2003BDR can be paralleled to increase total sink current - for example, two channels in parallel support up to 1 A per load. However, ensure matched trace lengths and identical external connections to minimize current imbalance. Thermal derating must be recalculated using total power dissipation (P_D = ΣI_C × V_CE(sat)) and adjusted for R_θJA; Figure 6 in the ULN2003BDR datasheet provides duty-cycle-limited current guidance for multi-channel operation.

Does the ULN2003BDR require external pull-up resistors when driving resistive loads?

Yes, the ULN2003BDR requires external pull-up resistors when driving resistive loads such as LEDs or logic inputs because its outputs are open-collector. Without a pull-up, the output remains floating in the high state. Typical values range from 1 kΩ to 10 kΩ depending on load current and speed requirements. For inductive loads, the COM pin serves as the effective pull-up via the clamp diode path, eliminating the need for discrete resistors.

How does the ULN2003BDR differ from the ULN2003A in terms of electrical performance?

The ULN2003BDR improves upon the ULN2003A with ≥4× lower collector cutoff current (I_CEX ≤20 μA vs ≤80 μA), optimized 2.7-kΩ input resistors for better CMOS compatibility, and updated thermal characterization per JESD 51-7. All other parameters - including 500 mA rating, 50 V output, pinout, and package options - remain identical. These enhancements make ULN2003BDR preferable for low-leakage, battery-sensitive, or high-reliability applications.

Is the ULN2003BDR RoHS-compliant and lead-free?

Yes, the ULN2003BDR is RoHS-compliant and lead-free. Per TI's packaging documentation, it uses matte tin (Sn) lead finish and meets JEDEC J-STD-020 moisture sensitivity level (MSL) 1 requirements. The part marking "ULN2003B" appears on the top surface, and full compliance data - including substance declarations and exemption status - is available in TI's official ULN2003BDR product folder and material content reports.