STMicroelectronics ULN2003TTR

Overview

ULN2003TTR from STMicroelectronics is a 7-channel high-voltage, high-current Darlington array IC with integrated flyback diodes, designed for driving inductive loads such as relays and solenoids. It delivers 500 mA continuous output current per channel (600 mA peak), supports 5 V TTL/CMOS logic inputs, and operates up to 50 V output voltage. Used in industrial control I/O modules and printer head drivers.

For engineers reviewing the ULN2003TTR datasheet, ULN2003TTR pinout, ULN2003TTR application, or ULN2003TTR equivalent, key selection criteria include per-channel current capability, integrated clamp diode functionality, thermal resistance in TSSOP16, input compatibility with 5 V logic families, and layout-optimized pin arrangement (inputs opposite outputs).

Technical Context

The ULN2003TTR integrates seven independent open-collector NPN Darlington pairs with common emitters and monolithically integrated clamping diodes across each collector-emitter path. Each channel features a base resistor network enabling direct 5 V TTL/CMOS interface without external biasing.

Its architecture supports parallel connection of outputs for increased current drive, and its input-output pin mirroring simplifies PCB routing in multi-relay driver designs. Thermal performance is defined by R_thJA = 93.3 °C/W in TSSOP16, limiting continuous full-load operation to ambient temperatures below 65 °C without heatsinking.

Key Specifications

Pinout & Package

TSSOP16 surface-mount package (4.9 × 6.4 mm footprint, 1.2 mm height), optimized for space-constrained industrial and printer control boards.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ULN2003A and ULN2003D1013TR, the ULN2003TTR trades thermal margin for minimal PCB area-ideal for compact, high-density designs where 500 mA/channel and 65 °C max ambient are sufficient.

Availability

ULN2003TTR is available at Aetrix Electronics and suitable for industrial automation I/O modules, thermal printer subsystems, and LED matrix display drivers requiring stable component supply across extended production lifecycles.

Supply support for ULN2003TTR 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, designing and manufacturing analog, mixed-signal, power, and microcontroller solutions for industrial, automotive, and consumer markets.

The ULN2003TTR belongs to ST's legacy high-voltage interface IC product line, engineered specifically for robust, cost-effective driving of electromechanical and resistive loads in harsh industrial environments.

FAQ

Can ULN2003TTR drive a 12 V relay with 70 mA coil current?

Yes. With a 70 mA coil current, the ULN2003TTR operates well within its 500 mA continuous rating and exhibits V_CE(SAT) ≤ 1.1 V, resulting in <80 mW power dissipation per channel-well below its thermal limit in TSSOP16 at room temperature.

Is a pull-up resistor required on the output pins?

Yes. The ULN2003TTR has open-collector outputs; each OUTx pin must be connected to the positive side of the load (e.g., relay coil or LED anode) and pulled up to the load supply voltage (≤50 V) via the load itself or an external resistor if driving high-impedance nodes.

What is the purpose of the COM pin (Pin 16)?

The COM pin connects the cathodes of all seven internal clamp diodes. It must be tied to the same positive voltage rail as the loads' other terminals (e.g., +24 V) to provide a return path for inductive kickback energy, preventing voltage spikes that could damage the IC or upstream circuitry.

Does ULN2003TTR support PWM operation for thermal printhead control?

Yes. With t_PLH/t_PHL ≤ 1 µs and h_FE ≥ 1000 at 350 mA, it supports PWM frequencies up to 100 kHz for precise thermal element current control-sufficient for standard thermal printer dot timing and grayscale modulation.