ULN2003ADR - 50V 500mA 7-ch Darlington Array SOIC-16 | TI
MPN: ULN2003ADR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.41 | $0.41 |
| 10 | $0.36 | $3.60 |
| 100 | $0.27 | $27.00 |
| 500 | $0.22 | $110.00 |
| 1,000 | $0.19 | $190.00 |
| 2,500 | $0.16 | $400.00 |
ULN2003ADR Overview
A Darlington transistor array is a monolithic IC that integrates multiple high-gain Darlington-pair switches, each formed by two cascaded bipolar transistors whose collectors tie together and whose emitters drive the load. Within the broader taxonomy, the ULN2003ADR sits under: transistor array -> bipolar transistor array -> Darlington array -> driver IC -> semiconductor. Each pair typically delivers beta > 1000, so a few milliamps of input current can switch hundreds of milliamps at the output. This integration simplifies board design by replacing seven discrete NPN transistors plus seven base resistors with a single 16-pin IC.
Key features include 500 mA continuous collector current per channel, 50 V minimum output breakdown, integrated flyback diodes, and logic-level inputs compatible with 3.3 V and 5 V microcontrollers. The open-collector outputs allow flexible pull-up voltage selection independent of the logic supply. The SOIC-16 (D) package offers a small footprint suitable for reflow soldering, with all seven channels and the common-cathode clamp brought out for easy PCB routing.
The architecture is bipolar; the seven Darlington pairs share a common emitter (substrate) tied to the GND pins. Total power dissipation for the package is approximately 0.95 W at 25 C, derating linearly with temperature. Channel-to-channel matching is tight because all pairs share the same silicon die, which is critical for stepper motors and multi-coil relay banks requiring matched drive strength.
Typical applications include unipolar stepper motor drivers, relay and solenoid drivers, lamp and LED matrix drivers, and logic-level buffers for higher-current loads. In each case the ULN2003ADR replaces discrete driver circuits with a single IC, reducing PCB area and BOM count. When designing with this device, ensure that the total package dissipation stays below the derated limit by calculating the worst-case voltage drop across each conducting Darlington and summing across active channels. The clamp diodes handle inductive kickback, but the user must still size the supply decoupling appropriately for the load.
Drop-in alternatives for ULN2003ADR — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with ULN2003ADR (same form factor and footprint) — differing in Operating Temperature Range, Package, RoHS Status.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ULN2003AD
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$0.0843 / Unit
View Datasheet →ULN2003ADRG3
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
ULN2003ADRE4
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
ULN2003ADR2G
✅ Drop-In📋 Reference alternative (not in catalog)
ULN2004ADR
✅ Drop-In📋 Reference alternative (not in catalog)
ULN2003ADR Maximum Ratings & Electrical Characteristics
| Transistor Type | 7 NPN Darlington Array |
| Number of Channels | 7 |
| Collector Current (Single Output, Max) | 500 mA |
| Collector-Emitter Voltage (Max) | 50 V |
| Output Breakdown Voltage (Min) | 50 V |
| Input Type | Logic-level compatible (TTL/CMOS) |
| Series Base Resistor | 2.7 kOhm |
| Output Configuration | Open-collector, common emitter |
| Clamp Diodes | Integrated common-cathode flyback diodes |
| Operating Temperature Range | -40 C to +70 C |
| Package | SOIC-16 (D) |
| Mounting Type | Surface Mount |
| MSL Level | 1 (unlimited) |
| RoHS Status | Compliant |
| Lead-Free | Yes |
ULN2003ADR Pin Configuration
| Pin 1 | 1B — Channel 1 input (base, with 2.7 kOhm series resistor) |
| Pin 2 | 2B — Channel 2 input |
| Pin 3 | 3B — Channel 3 input |
| Pin 4 | 4B — Channel 4 input |
| Pin 5 | 5B — Channel 5 input |
| Pin 6 | 6B — Channel 6 input |
| Pin 7 | 7B — Channel 7 input |
| Pin 8 | GND — Common emitter / substrate ground |
| Pin 9 | COM — Common-cathode clamp diode return (tie to load supply) |
| Pin 10 | 7C — Channel 7 output (open collector) |
| Pin 11 | 6C — Channel 6 output |
| Pin 12 | 5C — Channel 5 output |
| Pin 13 | 4C — Channel 4 output |
| Pin 14 | 3C — Channel 3 output |
| Pin 15 | 2C — Channel 2 output |
| Pin 16 | 1C — Channel 1 output |
Typical Applications
ULN2003ADR is suitable for 7 applications: Unipolar Stepper Motor Driver, Relay and Solenoid Driver Array, LED Matrix and 7-Segment Display Driver, Logic-Level Buffer for Higher-Current Loads, Hammer Driver for Impact Printers and Dot-Matrix Heads, Automotive and Industrial Lamp Driver, Capacitive Touch Key LED Backlight Driver.
Unipolar Stepper Motor Driver
The ULN2003ADR's seven NPN Darlington channels drive the four coils of a 28BYJ-48 or similar 5-wire unipolar stepper motor directly from a 3.3 V or 5 V microcontroller. Each channel's 500 mA rating covers the typical 100-240 mA per-phase coil current, while the integrated clamp diodes absorb the back-EMF when coils de-energize. The 50 V breakdown provides ample margin above the 12 V supply used for hobby steppers. Engineers wire four MCU GPIOs to inputs 1B-4B and tie the motor common to 12 V, then pulse the four lines in sequence to step the motor. The remaining three channels remain unused or drive status LEDs. Compared to discrete NPN arrays, the integrated base resistors eliminate seven external components and the matched die ensures equal current sharing across phases.
Recommended
Relay and Solenoid Driver Array
Each ULN2003ADR channel sinks up to 500 mA, making it well-suited for driving 5 V or 12 V signal relays and small solenoids that exceed MCU GPIO drive capability. The 2.7 kOhm input resistors allow direct connection to 3.3 V MCU logic without external drivers, and the open-collector outputs let the relay coil pull-up voltage (typically 12 V or 24 V) be set independently from the logic supply. The integrated common-cathode clamp diodes tied to pin 9 (COM) protect the IC from inductive kickback when the coil de-energizes; users connect the COM pin to the relay supply rail. With seven channels per IC, one ULN2003ADR handles an entire 7-relay bank in industrial control and home-automation designs, simplifying PCB layout versus seven discrete transistors.
Recommended
LED Matrix and 7-Segment Display Driver
The ULN2003ADR serves as a low-side driver for multi-digit 7-segment LED displays or LED bar-graph arrays, sinking up to 500 mA per segment. Each channel's open-collector output pairs naturally with the common-anode configuration of standard LED displays, with the display's anode tied to a current-limited high-side supply. The 50 V output rating means the IC also supports higher-voltage vacuum fluorescent (VFD) and neon indicator loads. Because all seven channels share tight Vce(sat) matching from the same die, segment brightness stays uniform across the display. The SOIC-16 footprint fits easily behind a 0.56-inch 7-segment display, enabling compact front-panel designs in white goods and industrial HMIs.
Recommended
Logic-Level Buffer for Higher-Current Loads
When a 3.3 V or 5 V microcontroller GPIO cannot source enough current for lamps, small DC motors, or Peltier elements, the ULN2003ADR provides a current-amplifying buffer that preserves the original control logic. Each channel accepts a few hundred microamps of input current and switches up to 500 mA at the load. The 50 V collector rating supports 24 V industrial rail applications, while the integrated base resistors eliminate any need for external current-limiting. Common uses include driving indicator lamps, small DC brushed fans, Peltier coolers, and heater elements in low-voltage appliances. The seven channels can also be paralleled for higher current with appropriate thermal management.
Recommended
Hammer Driver for Impact Printers and Dot-Matrix Heads
The ULN2003ADR's 7-channel architecture and 500 mA per-channel drive make it a classic hammer driver for impact printer solenoids, dot-matrix print heads, and similar pulsed-inductive loads. Each print hammer or pin solenoid is fired by one Darlington channel, with the COM pin tied to the solenoid supply rail so the integrated clamp diodes absorb the inductive kickback. Tight channel-to-channel Vce(sat) matching ensures consistent hammer impact force across all seven pins, which is critical for uniform print quality. The 50 V rating covers typical 24 V and 35 V hammer-driver supplies used in industrial receipt and ticket printers. The SOIC-16 package enables compact printer carriage designs.
Recommended
Automotive and Industrial Lamp Driver
The ULN2003ADR can drive indicator lamps, panel backlights, and small automotive relay coils where the supply rail is 12 V or 24 V and MCU logic runs at 3.3 V or 5 V. Each channel's 500 mA rating handles typical 12 V incandescent and LED lamp loads up to several watts, while the 50 V collector breakdown tolerates load-dump transients common in 12 V automotive systems when paired with appropriate external TVS protection. The open-collector outputs are inherently current-sinking, so high-side P-MOSFET drivers or PNP transistors are added when sourcing is required. The wide -40 C to +70 C operating temperature range suits under-hood and industrial cabinet environments, and the SOIC-16 footprint supports automated SMT assembly in volume production.
Recommended
Capacitive Touch Key LED Backlight Driver
In capacitive-touch human-machine interfaces, the ULN2003ADR drives the LED backlights behind each key while a separate touch controller handles the sensing. Each channel sinks up to 500 mA to illuminate one key's RGB LED string or single-color backlight, with PWM dimming generated directly by the MCU. The seven channels cover a typical 7-button front panel or single-digit 7-segment display. The 2.7 kOhm input resistors allow direct PWM from 3.3 V MCU logic, and the SOIC-16 footprint sits behind the touch panel without consuming significant PCB area. The integrated clamp diodes are useful when driving small inductive buzzer elements as key-press feedback alongside the LEDs.
Recommended
Recommended Products Summary
Engineering reference data for ULN2003ADR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ULN2003AD | ULN2003ADRG3 | ULN2003ADRE4 | ULN2003ADR2G | ULN2004ADR |
|---|---|---|---|---|---|---|
| Package | SOIC-16 (D) | SOIC-16 (D) | SOIC-16 (D) | SOIC-16 (D) | SOIC-16 (D) | SOIC-16 (D) |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | onsemi | Texas Instruments |
| Number of Channels | 7 | 7 | 7 | 7 | 7 | 7 |
| Collector Current (Max per Channel) | 500 mA | 500 mA | 500 mA | 500 mA | 500 mA | 500 mA |
| Collector-Emitter Voltage (Max) | 50 V | 50 V | 50 V | 50 V | 50 V | 50 V |
| Input Base Resistor | 2.7 kOhm | 2.7 kOhm | 2.7 kOhm | 2.7 kOhm | 2.7 kOhm | 10.5 kOhm |
| Logic Compatibility | 3.3 V / 5 V TTL/CMOS | 3.3 V / 5 V TTL/CMOS | 3.3 V / 5 V TTL/CMOS | 3.3 V / 5 V TTL/CMOS | 3.3 V / 5 V TTL/CMOS | 6 V to 15 V CMOS |
| Operating Temperature | -40 C to +70 C | -40 C to +70 C | -40 C to +70 C | -40 C to +70 C | -40 C to +85 C | -40 C to +70 C |
Key Differentiators
- On-die 2.7 kOhm base resistors for direct 3.3 V/5 V logic interface (vs ULN2803A)
- Integrated common-cathode clamp diodes on COM pin (vs Discrete NPN transistor array (e.g. 7 x 2N4401))
- Wide 50 V collector breakdown supports 24 V and 36 V industrial rails (vs TPL7407 (40 V max))
- Tight channel-to-channel Vce(sat) matching from shared silicon die (vs Discrete transistor solutions)
Design Notes
Estimated: With all 7 channels simultaneously conducting at 200 mA each into 12 V loads (Vce(sat) approximately 1.0 V at that current), package dissipation is roughly 7 channels x 200 mA x 1.0 V = 1.4 W. The SOIC-16 has a theta_JA of about 73 C/W on a standard JEDEC 4-layer test board, so junction temperature would rise about 102 C above ambient - exceeding the 70 C operating range. Derate current per channel or pulse-duty-cycle the load (e.g. stepper motor half-stepping) to stay within the 0.95 W package dissipation limit at 25 C.
Always connect the COM pin (pin 9) to the positive load supply rail. Without this connection the integrated clamp diodes have no return path and inductive kickback from relays or solenoids will destroy the outputs. For purely resistive loads like LED arrays where no inductance is present, the COM pin can be left open or tied to ground (though tying to the load supply is the safer default).
Place a 0.1 uF ceramic bypass capacitor on the load supply rail as close as possible to the COM pin, plus a 10 uF bulk capacitor if driving multiple inductive loads. The Darlington outputs share a common emitter trace on pin 8 (GND) - use a wide ground pour to handle the summed return current without significant voltage drop. For 28BYJ-48 stepper motors drawing 240 mA per phase, route the four phase outputs as matched-length traces to keep step timing symmetrical.
Do not parallel multiple ULN2003ADR channels to get more than 500 mA per output - the on-die base resistors and Vce(sat) matching are not characterized for parallel operation, and current hogging can occur. If more than 500 mA per channel is required, move up to the TPIC6B595 (with shift register) or discrete MOSFETs. Also, do not exceed 50 V on the collector outputs even momentarily - load-dump transients in 12 V automotive systems require an upstream TVS diode clamp.
When driving stepper motors at high step rates, the dV/dt on the open-collector outputs can inject noise into adjacent analog traces. Keep the ULN2003ADR outputs away from sensitive analog signal paths, or shield them with a ground trace. The Darlington pair has a typical turn-off time of several microseconds due to stored charge in the bipolar transistors, which limits maximum step rates to about 10 kHz per channel.
Compliance Information
RoHS compliant per TI ULN2003A product page. Not AEC-Q100 qualified - for automotive applications verify with TI or use a Q-graded Darlington array. Lead-free (Sn-plated or NiPdAu finish variants available).
