Texas Instruments ULQ2004AD

Overview

ULQ2004AD from Texas Instruments is a 7-channel high-voltage, high-current Darlington transistor array designed for interfacing low-voltage logic (6–15 V CMOS) with inductive loads. It delivers 500 mA per channel, supports 50 V collector-emitter voltage, integrates common-cathode clamp diodes, and uses 10.5 kΩ input base resistors for direct CMOS compatibility. It is widely deployed in relay and stepper motor control circuits.

For engineers reviewing the ULQ2004AD datasheet, ULQ2004AD pinout, ULQ2004AD application, or ULQ2004AD equivalent, key selection criteria include per-channel current capability, flyback diode integration, input resistor value for logic-level compatibility, thermal derating at elevated ambient temperatures, and SOIC-16 package footprint constraints.

Technical Context

The ULQ2004AD implements seven independent NPN Darlington pairs with integrated base-input resistors (10.5 kΩ), enabling direct drive from 6–15 V CMOS logic without external biasing. Each channel features an open-collector output and shares a common cathode (COM) node for internal clamp diodes.

It operates across –40°C to +85°C ambient temperature, with absolute maximum ratings of 50 V collector-emitter voltage and 500 mA peak collector current per channel. Switching propagation delays are 1–10 μs over full operating conditions, and thermal resistance (R_θJA) is 88.6°C/W in SOIC-16 package.

Key Specifications

Pinout & Package

ULQ2004AD is housed in a 16-pin SOIC package (9.90 mm × 3.91 mm), optimized for surface-mount assembly and thermal performance in space-constrained PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ULN2004AD and ULQ2004ADR, the ULQ2004AD offers identical electrical performance and SOIC-16 footprint but is specified for a narrower ambient range (–40°C to +85°C), making it optimal for cost-sensitive commercial and industrial control systems where extreme thermal margins are not required.

Availability

ULQ2004AD is available at Aetrix Electronics and suitable for relay drivers, stepper motor controllers, lamp drivers, and LED display interfaces requiring stable component supply and long-lifecycle support.

Supply support for ULQ2004AD 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 power management technologies with over 50 years of innovation in industrial and automotive electronics.

The ULQ2004AD belongs to TI's ULx200x Darlington array product line, engineered specifically for robust, low-component-count interfacing between modern CMOS logic and high-voltage/high-current electromechanical loads.

FAQ

What is the maximum continuous collector current per channel for ULQ2004AD?

The ULQ2004AD supports 500 mA maximum collector current per channel under recommended operating conditions. This rating assumes proper PCB copper area for heat dissipation and ambient temperature ≤70°C. At 85°C ambient, derating to ~350 mA per channel is advised based on its R_θJA of 88.6°C/W and 125°C max junction temperature.

Does ULQ2004AD require external flyback diodes when driving relays?

No, ULQ2004AD does not require external flyback diodes when driving relays. It integrates seven common-cathode clamp diodes connected to the COM pin. To use them, tie the COM pin to the positive side of the relay coil supply - this provides automatic inductive kickback suppression during turn-off.

What logic families can directly drive ULQ2004AD inputs?

ULQ2004AD inputs are optimized for direct drive from 6–15 V CMOS logic families due to its internal 10.5 kΩ base resistors. It also accepts TTL-level signals (≥2.0 V high) but is not intended for 3.3 V logic without external pull-up or level-shifting, as its VI(on) threshold starts at ~2.7 V for 200 mA load.

How does ULQ2004AD differ from ULN2004AD?

The ULQ2004AD and ULN2004AD share identical pinout, electrical specifications, and SOIC-16 packaging. Their key difference is temperature rating: ULQ2004AD is specified for –40°C to +85°C ambient, while ULN2004AD extends to +105°C. Both use the same 10.5 kΩ input resistors and deliver 500 mA/channel.

Can multiple ULQ2004AD outputs be paralleled to increase current capacity?

Yes, ULQ2004AD outputs can be paralleled to increase current capacity - for example, two channels in parallel support up to 1 A sink current. However, ensure matched trace lengths and thermal coupling, and verify total power dissipation against R_θJA (88.6°C/W) to avoid exceeding 125°C junction temperature.