ULN2803APG - 8ch Darlington Sink Driver, 50V, 500mA DIP-18
MPN: ULN2803APG ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.1 | $2.10 |
| 10 | $1.85 | $18.50 |
| 100 | $1.55 | $155.00 |
| 500 | $1.32 | $660.00 |
| 1,000 | $1.18 | $1,180.00 |
ULN2803APG Overview
A Darlington transistor array is a monolithic bipolar IC that pairs two NPN transistors so the emitter of the first drives the base of the second, multiplying current gain (hFE typically > 1000). Eight such pairs share a common-emitter ground pin, forming an 8-channel low-side switch well suited to driving relays, solenoids, stepper motor windings, lamp filaments, and LED displays from low-power digital logic. The ULN2803 family sits within the broader hierarchy of bipolar transistor arrays → interface ICs → driver ICs → power management.
Key specifications of the ULN2803APG include 500 mA continuous collector current per channel, 50 V VCEO sustain voltage, integrated free-wheeling clamp diodes on each output for inductive load protection, and an input structure compatible with 5 V CMOS logic levels. The DIP-18 footprint matches industry-standard pinouts used by competing parts from TI, STMicroelectronics, and Allegro, simplifying PCB migration.
Typical applications span relay drivers in industrial control, hammer/lamp drivers in point-of-sale and copier equipment, LED/display matrix drivers, and stepper or DC motor bridge half-drivers. The integrated clamp diodes eliminate external snubbers on solenoids and relay coils, reducing BOM count and improving long-term reliability against back-EMF transients.
When designing with this device, observe the package power dissipation limit of 760 mW for the DIP-18 variant and derate per channel when multiple outputs switch simultaneously at high duty cycle. The common-emitter architecture makes the ULN2803APG strictly a low-side (sink) driver — for high-side (source) driving use the complementary ULN2803 family high-side counterpart or a PNP/PMOS array.
Drop-in alternatives for ULN2803APG — 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 ULN2803APG (same form factor and footprint) — differing in Package, Mounting Type, Clamp Diodes, DC Current Gain (hFE), Input Base Resistor.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ULN2803AFWG
✅ Drop-In📋 Reference alternative (not in catalog)
ULN2803APG
✅ Drop-In✓ In Stock
$1.18 / Unit
View Datasheet →ULN2804APG
✅ Drop-In📋 Reference alternative (not in catalog)
ULN2803AN
✅ Drop-In📋 Reference alternative (not in catalog)
ULN2803ADWR
✅ Drop-In✓ In Stock
$0.38 / Unit
View Datasheet →ULN2803ADWR
✅ Drop-In✓ In Stock
$0.38 / Unit
View Datasheet →ULN2803APG Maximum Ratings & Electrical Characteristics
| Number of Channels | 8 |
| Transistor Type | 8x NPN Darlington Pairs |
| Configuration | Common-emitter, 8-channel sink driver |
| Collector-Emitter Voltage (Vceo) | 50 V |
| Continuous Collector Current (per channel) | 500 mA |
| Package Power Dissipation | 760 mW (DIP-18) |
| DC Current Gain (hFE) | Typical > 1000 (Darlington) |
| Input Base Resistor | 2.7 kOhm |
| Logic Input Compatibility | 5 V CMOS / TTL |
| Clamp Diodes | Integral free-wheeling diodes on each output |
| Operating Temperature | -40C to +85C |
| Mounting Type | Through-Hole |
| Package | DIP-18 (0.300 inch, 7.62 mm) |
| Pin Count | 18 |
| RoHS Status | Compliant |
ULN2803APG Pin Configuration
| Pin 1 | IN1 — Channel 1 input (base of Darlington pair) |
| Pin 2 | IN2 — Channel 2 input |
| Pin 3 | IN3 — Channel 3 input |
| Pin 4 | IN4 — Channel 4 input |
| Pin 5 | IN5 — Channel 5 input |
| Pin 6 | IN6 — Channel 6 input |
| Pin 7 | IN7 — Channel 7 input |
| Pin 8 | IN8 — Channel 8 input |
| Pin 9 | GND — Common emitter / ground |
| Pin 10 | COM — Common cathode of clamp diodes (tie to load supply) |
| Pin 11 | OUT8 — Channel 8 output (open collector) |
| Pin 12 | OUT7 — Channel 7 output |
| Pin 13 | OUT6 — Channel 6 output |
| Pin 14 | OUT5 — Channel 5 output |
| Pin 15 | OUT4 — Channel 4 output |
| Pin 16 | OUT3 — Channel 3 output |
| Pin 17 | OUT2 — Channel 2 output |
| Pin 18 | OUT1 — Channel 1 output |
Typical Applications
ULN2803APG is suitable for 6 applications: Industrial Relay Driver Arrays, Solenoid and Hammer Driver (Printer/POS), LED Matrix and Display Driver, Stepper Motor Bridge Half-Driver, Automotive Lamp and Indicator Driver, Logic-Level Buffer / Level Shifter.
Industrial Relay Driver Arrays
The ULN2803APG is widely used as a 24 V industrial relay driver because each channel sinks up to 500 mA at 50 V VCEO, comfortably exceeding the 20-30 mA typical holding current of signal relays. Place the relay coil between +24 V and the ULN2803APG output pin; the 5 V CMOS logic on the input pin drives the Darlington pair directly without a buffer. The integral free-wheeling clamp diode eliminates the external flyback diode traditionally required across each coil, reducing BOM count and PCB area. With 8 channels per IC, a single ULN2803APG replaces eight discrete transistors and eight diodes in a PLC output module or home automation relay board.
Recommended
Solenoid and Hammer Driver (Printer/POS)
In dot-matrix print heads, POS cash drawers, and valve controllers, the ULN2803APG drives 8 solenoid or hammer coils directly from a microcontroller. Each channel's 500 mA rating covers most 12-24 V solenoids, while the integrated clamp diode absorbs the inductive kickback generated when the coil de-energizes. The 2.7 kOhm base resistor ensures the input current stays below 2 mA at 5 V, so any 5 V CMOS GPIO can drive the input without an external buffer. The DIP-18 package suits legacy through-hole printer controller boards and field-replaceable designs.
Recommended
LED Matrix and Display Driver
The ULN2803APG multiplexes rows or columns in 7-segment LED displays, dot-matrix panels, and large LED arrays. Each channel's 500 mA supports parallel LED strings of up to ~8 standard 20 mA LEDs per output, and 8 channels simplify scanning architectures for 8-row or 8-column matrix designs. The low-side sinking architecture pairs naturally with PNP high-side drivers or P-MOSFET high-side switches for full H-bridge LED matrix driving. The 50 V VCEO margin accommodates long LED chains with stacked supply rails. The DIP-18 form factor is convenient for hobbyist and educational electronics prototyping kits.
Recommended
Stepper Motor Bridge Half-Driver
Two ULN2803APG ICs form the low-side half of a unipolar stepper motor bridge, with each IC handling one phase of a bipolar or unipolar stepper. The 500 mA per channel rating covers most NEMA 14, NEMA 17, and small NEMA 23 stepper windings at low duty cycles; for higher current motors, parallel two channels per phase. The Darlington pair's high hFE (>1000) means the microcontroller can directly toggle the phase winding without a discrete driver stage. With 8 channels, a single ULN2803APG can drive two phases of a bipolar stepper plus auxiliary relays.
Recommended
Automotive Lamp and Indicator Driver
Although the ULN2803APG is not AEC-Q100 qualified, it is commonly used in non-safety automotive subsystems such as interior dome lamp controllers, dashboard indicator multiplexers, and aftermarket accessory drivers where 24 V truck body systems are common. Each channel handles 500 mA at 50 V, accommodating 12 V or 24 V lamp loads with adequate transient headroom. Designers typically add external TVS protection and a fuse per channel for automotive reliability. For AEC-Q100 applications, the TI ULN2803AQ or qualified alternatives must be substituted.
Recommended
Logic-Level Buffer / Level Shifter
Beyond power driving, the ULN2803APG acts as a logic buffer that translates low-current 3.3 V or 5 V microcontroller outputs to higher-current 12 V or 24 V peripheral rails. The Darlington pair provides both current amplification and voltage translation up to 50 V, useful for driving vacuum fluorescent displays (VFDs), large relays, and high-voltage optocouplers. The 2.7 kOhm input resistor limits input current such that even 3.3 V GPIO can drive the inputs with adequate base current. The DIP-18 package makes it breadboard-friendly for prototyping and educational kits.
Recommended
Recommended Products Summary
Engineering reference data for ULN2803APG — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ULN2803AFWG | ULN2803AN | ULN2803A | ULN2804APG | ULN2803 |
|---|---|---|---|---|---|---|
| Package | DIP-18 (THT) | SOP-18 wide-body (SMD) | DIP-18 (THT) - same | DIP-18 (THT) - same | DIP-18 (THT) - same | DIP-18 (THT) - same |
| Brand | Toshiba | Toshiba | Texas Instruments | STMicroelectronics | Toshiba | Allegro Microsystems |
| Channels | 8 | 8 | 8 | 8 | 8 | 8 |
| VCEO Max | 50 V | 50 V | 50 V | 50 V | 50 V | 50 V |
| Continuous Collector Current / Channel | 500 mA | 500 mA | 500 mA | 500 mA | 500 mA | 500 mA |
| Input Base Resistor | 2.7 kOhm | 2.7 kOhm | 2.7 kOhm | 2.7 kOhm | 10.5 kOhm | 2.7 kOhm |
| Clamp Diodes | Yes (integral) | Yes (integral) | Yes (integral) | Yes (integral) | Yes (integral) | Yes (integral) |
| Mounting Type | Through-Hole | Surface Mount | Through-Hole | Through-Hole | Through-Hole | Through-Hole |
Key Differentiators
- Established Toshiba quality with broad second-source availability (vs ULN2803AN (Texas Instruments))
- Higher package power dissipation than some equivalents (vs ULN2803A (STMicroelectronics))
- 2.7 kOhm base resistor for 5 V CMOS direct drive (vs ULN2804APG (Toshiba))
Design Notes
The DIP-18 package has a maximum power dissipation of 760 mW at 25C per the Toshiba ULN2803APG datasheet and DigiKey listing. With all 8 channels sinking 500 mA simultaneously, even at modest VCE(sat) of 1.0 V, total internal dissipation would be 4 W and exceed the package rating. Estimated: at 8 channels active the designer must derate per-channel current to ~100 mA or implement external heat-sinking. In practice most applications switch only a few channels at a time, so dissipation stays within spec.
The ULN2803APG is a low-side (sink) driver ONLY — the load must connect between V+ and the ULN2803APG output pin, with the IC switching the low side to ground. Connecting the load between the output and ground will not work because the Darlington's collector is left floating. For high-side (source) driving, use the Toshiba TD62783APG (PNP source array) which shares the same 18-pin DIP pinout for layout compatibility. Also, the COM pin (pin 10) is the common cathode of the clamp diodes and must be tied to the load supply voltage — leaving it floating disables inductive load protection and risks device damage from back-EMF.
Place the ULN2803APG close to the load connectors to minimize the high-current trace length between the IC outputs and the relay coils/solenoids. Keep the COM (pin 10) trace short and direct to the load V+ supply; long traces allow inductive transients to develop voltage spikes that can exceed the clamp diode ratings. For DIP-18 through-hole designs, use wide copper pours (at least 0.5 mm/20 mil) on the output traces to handle the 500 mA continuous current without significant voltage drop. Decouple the logic supply with a 100 nF ceramic capacitor near the GND pin if the inputs are driven from a noisy source.
Compliance Information
RoHS compliant per Toshiba ULN2803APG product page and current distributor listings. DIP-18 G-suffix indicates green (RoHS) molding compound. AEC-Q100 qualification not applicable to standard ULN2803APG - look for ULN2803AQ or qualified alternatives for automotive safety applications.
