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Texas Instruments ULN2003AD
- Part No.:
- ULN2003AD
- Manufacturer:
- Texas Instruments
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
ULN2003AD.pdf
- Description:
- TRANS 7NPN DARL 50V 0.5A 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,505
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Product details
Overview
ULN2003AD from Texas Instruments is a 7-channel high-voltage, high-current NPN Darlington transistor array designed for logic-level interfacing to inductive and resistive loads. It delivers 500mA per channel, supports 50V collector-emitter voltage, integrates input base resistors (2.7kΩ), features built-in common-cathode clamp diodes, and operates with TTL/5V CMOS inputs - widely used in relay, stepper motor, and LED display driver circuits.
For engineers reviewing the ULN2003AD datasheet, ULN2003AD pinout, ULN2003AD application, or ULN2003AD equivalent, key selection criteria include per-channel current capability, integrated flyback protection, input compatibility with 3.3V/5V logic, thermal derating at elevated ambient temperatures, and SOIC-16 package footprint constraints for PCB layout.
Technical Context
The ULN2003AD implements seven independent Darlington pairs, each formed by cascaded NPN transistors to achieve high DC current gain (β² ≈ 10⁴), enabling low-input-current switching of high-load currents. Its internal 2.7kΩ series base resistor allows direct connection to 3.3V or 5V logic without external biasing.
All outputs are open-collector with common-emitter (E) and common-cathode clamp diode (COM) terminals. The COM pin must be connected to the inductive load supply rail to enable flyback energy recirculation, while E is tied to system ground - defining its role as a grounded-sink driver rather than a high-side switch.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Channel count | 7 independent Darlington sink channels - enables parallel control of relays, motor phases, or LED segments without discrete transistor arrays. |
| Max collector current (per channel) | 500mA continuous - supports driving 12V/24V relays (e.g., OMRON G5NB), small solenoids, or up to 7× 70mA LEDs simultaneously. |
| Collector-emitter voltage (VCE) | 50V - accommodates industrial control voltages up to 48V DC and suppresses inductive kickback spikes within safe operating limits. |
| Input resistor value | 2.7kΩ per channel - sets nominal input current to ~1.85mA at 5V, ensuring reliable turn-on with standard TTL/CMOS outputs without external components. |
| VCE(sat) @ IC = 350mA | 1.2V typical - results in ≤420mW power dissipation per active channel, critical for thermal management in multi-channel operation. |
| Switching speed (tPLH/tPHL) | 0.25–1μs - sufficient for relay actuation and stepper motor microstepping at ≤20kHz, but not suitable for high-frequency PWM dimming. |
| Operating temperature range | –40°C to +105°C - qualified for automotive under-hood and industrial embedded environments where extended thermal stability is required. |
Pinout & Package
ULN2003AD is housed in a 16-pin SOIC (Small Outline Integrated Circuit) package measuring 9.90mm × 3.91mm, with standard 1.27mm pitch and surface-mount gull-wing leads.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1B–7B (Pins 1–7) | Input base terminals | Accept TTL/CMOS logic signals; internally biased via 2.7kΩ resistors to predriver Darlington bases - no external pull-up/down needed. |
| 1C–7C (Pins 16–10) | Open-collector collector outputs | Sink current to ground; require external pull-up or load connection to positive rail - configured as low-side switches. |
| E (Pin 8) | Common emitter | Internally tied to all emitter nodes; must be connected to system ground to complete current paths for all channels. |
| COM (Pin 9) | Common cathode clamp node | Connect to inductive load supply rail (e.g., +12V) to provide path for flyback current - essential for relay/solenoid reliability. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated clamp diodes | Seven common-cathode diodes across outputs and COM eliminate need for external flyback diodes in relay/motor applications - reduces BOM count and board area. |
| Logic-compatible input stage | 2.7kΩ series base resistors enable direct interface with 3.3V or 5V MCU GPIOs - avoids level-shifting circuitry and simplifies firmware control. |
| High-current Darlington architecture | Current gain >10,000 enables 500mA output with only ~500μA input drive - ideal for resource-constrained microcontrollers with limited I/O current capability. |
| Thermally robust SOIC package | RθJA = 88.6°C/W - supports sustained multi-channel operation at ambient temperatures up to 70°C without forced airflow or heatsinking. |
| Wide supply voltage tolerance | 50V VCE rating allows use with 24V PLC outputs, 48V telecom systems, and legacy industrial control rails - extends design reuse across platforms. |
Applications
| Relay Control Systems | Stepper Motor Drivers |
|---|---|
Use Scenario: Driving 12V/24V electromagnetic relays in programmable logic controllers (PLCs) and HVAC control panels. IC Role / Device Role / Timing Role: Low-side sink switch that replaces discrete transistor+diode combinations for each relay coil. Use Value: Eliminates 14 external components per 7-relay bank, reduces PCB area by >35%, and ensures consistent turn-off timing with integrated flyback clamping. |
Use Scenario: Controlling unipolar stepper motors in 3D printers and CNC motion controllers using microstep sequencing. IC Role / Device Role / Timing Role: Phase current sink for four-phase windings, synchronized to MCU step pulses. Use Value: Delivers 350mA per phase at <1.2V saturation drop, limiting power loss to <420mW/channel and enabling compact motor driver modules. |
| LED Display Panels | Industrial Lamp Drivers |
Use Scenario: Multiplexed 7-segment or dot-matrix LED displays requiring high-current segment sinking in factory HMIs. IC Role / Device Role / Timing Role: Column driver in common-anode matrix configurations, activated during row scan cycles. Use Value: Sustains 500mA peak current per segment for bright red/green LEDs while maintaining <1.3V VCE(sat) at 200mA - improves display contrast and longevity. |
Use Scenario: Switching incandescent and halogen indicator lamps in test equipment and power distribution units. IC Role / Device Role / Timing Role: Solid-state replacement for mechanical lamp sockets, handling inrush currents up to 10× steady-state. Use Value: Withstands 50V transient surges and absorbs lamp filament cold-resistance spikes without latch-up - increases field reliability vs. MOSFET alternatives. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Darlington array applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ULN2003ADR | Same electrical specs, but rated for –40°C to +105°C operation (vs. ULN2003AD's –40°C to +70°C); identical SOIC-16 package. | Required for automotive under-hood or extended-temperature industrial deployments where junction temperature exceeds 125°C. | Select ULN2003ADR when ambient operating temperature exceeds 70°C or when AEC-Q200 qualification is mandated. |
| STMicroelectronics ULN2003APG | Pin-compatible PDIP-16 variant with same 500mA/50V ratings; lacks SOIC thermal performance (RθJA = 66.7°C/W). | Suitable for prototyping and through-hole assembly, but requires larger board area and reduced channel density vs. SOIC. | Choose ULN2003APG for breadboard evaluation or legacy through-hole production lines where SOIC reflow is unavailable. |
Compared with ULN2003AD, ULN2003ADR offers extended temperature capability without layout changes, while ULN2003APG trades thermal efficiency for assembly flexibility - both retain identical functional behavior and pinout, enabling drop-in substitution in non-thermal-critical designs.
Availability
ULN2003AD is available at Aetrix Electronics and suitable for relay control systems, stepper motor drivers, and LED display panels requiring stable component supply across industrial automation, building management, and embedded instrumentation programs.
Supply support for ULN2003AD 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 over 50 years of innovation in industrial and automotive-grade components.
The ULN2003AD belongs to TI's legacy high-voltage Darlington array product line, engineered specifically for robust logic-to-load interfacing in harsh environments - emphasizing reliability, ease of use, and long-term manufacturability.
FAQ
What is the maximum continuous current per channel for ULN2003AD?
The ULN2003AD supports 500mA continuous collector current per Darlington channel under recommended operating conditions (TA ≤ 70°C, proper PCB copper area). Derating is required above 70°C ambient - e.g., ~350mA at 100°C - based on RθJA = 88.6°C/W and maximum junction temperature of 125°C. This rating applies to steady-state DC loads, not pulsed operation.
Can ULN2003AD drive 3.3V logic directly?
Yes, ULN2003AD accepts 3.3V logic inputs directly due to its internal 2.7kΩ series base resistors. At 3.3V, input current is ~1.22mA - sufficient to saturate the Darlington pair with guaranteed VCE(sat) ≤ 1.3V at 200mA load. No level-shifter or external resistor is needed, making it compatible with modern low-voltage MCUs.
Is a flyback diode required when using ULN2003AD with relays?
No external flyback diode is required when using ULN2003AD with relays, provided the COM pin is connected to the relay coil's positive supply rail. The device integrates seven common-cathode clamp diodes that recirculate inductive kickback energy safely. Omitting the COM connection invalidates this protection and risks device failure.
What is the purpose of the E (emitter) pin on ULN2003AD?
The E pin (Pin 8) is the common emitter connection for all seven Darlington pairs and must be tied to system ground. It serves as the return path for all sink currents - unlike high-side switches, ULN2003AD cannot operate without this ground reference. Floating or misconnecting E prevents any channel from conducting.
How does ULN2003AD differ from ULN2003A in part numbering?
ULN2003AD denotes the SOIC-16 package variant (D suffix) of the ULN2003A family. The base part ULN2003A defines the electrical functionality, while the suffix specifies packaging: D = SOIC, N = PDIP, PW = TSSOP. All variants share identical Darlington architecture, 500mA rating, 2.7kΩ input resistors, and 50V VCE, differing only in thermal and mechanical properties.
ULN2003AD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Series:
- ULx200xA
- Packaging:
- Tube
- Product Status:
- Obsolete
- Switch Type:
- Relay, Solenoid Driver
- Number of Outputs:
- 7
- Ratio - Input:Output:
- 1:1
- Output Configuration:
- Low Side
- Output Type:
- Darlington
- Interface:
- Parallel
- Voltage - Load:
- 50V (Max)
- Voltage - Supply (Vcc/Vdd):
- Not Required
- Current - Output (Max):
- 500mA
- Rds On (Typ):
- -
- Input Type:
- Inverting
- Features:
- -
- Fault Protection:
- -
- Operating Temperature:
- -40°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
ULN2003AD FAQ
1.How can I place an order for ULN2003AD through Aetrix?
Please submit a Request for Quotation (RFQ) for ULN2003AD on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for ULN2003AD reliable?
The price and inventory of ULN2003AD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ULN2003AD is usually 5 days.
3.What payment methods are accepted for ULN2003AD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ULN2003AD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ULN2003AD?
ULN2003AD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ULN2003AD order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for ULN2003AD?
For technical support, including ULN2003AD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ULN2003AD requirements.
6.How does Aetrix verify that ULN2003AD is sourced from the original manufacturer or authorized distributors?
All ULN2003AD products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ULN2003AD meets industry standards.
7.What is the process for return or replacement of ULN2003AD?
All ULN2003AD units undergo pre-shipment inspection (PSI). If there is an issue with ULN2003AD, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The ULN2003AD part is unused and in its original packaging.
Return procedure for ULN2003AD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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