UDN2981A - 8-Ch Source Driver, 80V, -500mA | Allegro | DIP-18
N.º de pieza: UDN2981A ✗ Fin de vida| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $2.85 | $2,85 |
| 10 | $2.55 | $25,50 |
| 100 | $2.15 | $215,00 |
| 500 | $1.85 | $925,00 |
| 1.000 | $1.55 | $1.550,00 |
UDN2981A Descripción general
What is a source driver? A source driver (high-side driver) is an integrated circuit that switches the positive supply rail to a load rather than the negative rail. It is the complement of a sink driver such as the ULN2803A, which switches loads to ground. Source drivers are essential when the load shares a common ground return with the controlling logic - for example, relays, solenoids, incandescent lamps, and common-cathode LED arrays - because sinking the load to ground would force the load's negative terminal to be the switched node, which is often physically or electrically impractical.
Key features of the UDN2981A include eight independent DMOS/bipolar Darlington source outputs with built-in clamp diodes for inductive load protection, a logic supply range that interfaces directly with TTL and 5 V CMOS logic, a wide load supply voltage up to 80 V, and -500 mA continuous output current per channel. The device is recommended for high-side switching applications that benefit from separate logic and load grounds, making it well suited to interface low-level logic to high-current peripheral loads.
Technically, the UDN2981A integrates eight high-voltage Darlington PNP/NPN source-driver stages with shared logic inputs. Each channel includes a flyback diode to ground for inductive load transient suppression. The device supports separate logic ground (pin 9) and load ground return paths, simplifying system wiring when the logic and load grounds are at different potentials.
Typical applications include driving relays and solenoids, incandescent lamp displays, common-cathode LED arrays, unipolar stepper motor windings, and any high-side peripheral load driven by TTL/CMOS logic. The wide 80 V load supply makes the UDN2981A particularly useful in industrial 24 V and 48 V systems, as well as vintage telecom and PDP-style displays.
When designing with the UDN2981A, place a 0.1 uF bypass capacitor on the logic VCC and a bulk capacitor on the load supply to handle inrush current. Ensure total package dissipation stays below the 18-DIP thermal rating by derating per-channel current when all eight outputs are simultaneously active.
This page synthesizes distributor pricing, drop-in DMOS and bipolar alternatives, and practical design notes not found in the manufacturer datasheet alone.
Alternativas directas para UDN2981A — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
UDN2981A-T
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
UDN2982A
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
UDN2984A
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
TBD62783A
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
A2982SLW
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
UDN2981A Valores máximos y características eléctricas
| Product Type | 8-channel source driver (high-side switch array) |
| Number of Channels | 8 |
| Configuración de salida | High-side (source) |
| Load Supply Voltage (Max) | 80 V |
| Continuous Output Current (per channel) | -500 mA |
| Tipo de salida | Bipolar Darlington open-collector PNP source |
| Logic Supply Voltage | 5 V (TTL/CMOS compatible) |
| Input Compatibility | TTL, 5 V CMOS |
| Clamp Diodes | Built-in for inductive loads |
| Encapsulado | 18-pin DIP (through-hole) |
| Tipo de montaje | Through-Hole |
| Temperatura de funcionamiento | -20 C to +85 C |
| Load Ground vs Logic Ground | Separate pins supported |
| Family Members | UDN2981A, UDN2982A, UDN2983A, UDN2984A (UDN2981-2984 family) |
Configuración de pines de UDN2981A
| Pin 1 | IN1 — Logic input, channel 1 (TTL/CMOS) |
| Pin 2 | IN2 — Logic input, channel 2 (TTL/CMOS) |
| Pin 3 | IN3 — Logic input, channel 3 (TTL/CMOS) |
| Pin 4 | IN4 — Logic input, channel 4 (TTL/CMOS) |
| Pin 5 | IN5 — Logic input, channel 5 (TTL/CMOS) |
| Pin 6 | IN6 — Logic input, channel 6 (TTL/CMOS) |
| Pin 7 | IN7 — Logic input, channel 7 (TTL/CMOS) |
| Pin 8 | IN8 — Logic input, channel 8 (TTL/CMOS) |
| Pin 9 | GND (Logic) — Logic ground return for inputs |
| Pin 10 | VCC (Logic) — Logic supply, 5 V typical |
| Pin 11 | OUT8 — Source output, channel 8 |
| Pin 12 | OUT7 — Source output, channel 7 |
| Pin 13 | OUT6 — Source output, channel 6 |
| Pin 14 | OUT5 — Source output, channel 5 |
| Pin 15 | OUT4 — Source output, channel 4 |
| Pin 16 | OUT3 — Source output, channel 3 |
| Pin 17 | OUT2 — Source output, channel 2 |
| Pin 18 | OUT1 — Source output, channel 1 |
Aplicaciones típicas
UDN2981A es adecuado para 6 aplicacións: Relay and Solenoid Driver Arrays, High-Side LED Array Driver, Incandescent Lamp and 7-Segment Display Driver, Unipolar Stepper Motor Winding Driver, Vintage PDP and Teletype Peripheral Driver, Industrial 24V/48V Load Driver Card.
Relay and Solenoid Driver Arrays
The UDN2981A is well suited to driving arrays of relays and solenoids from TTL/CMOS logic because each of its eight source outputs can switch up to 500 mA at 80 V load supply - more than enough headroom for 24 V industrial relay coils and small solenoids. Its built-in flyback clamp diodes protect the IC from inductive kickback when coils de-energize, removing the need for external freewheeling diodes. In a typical PLC or industrial-control card, eight logic inputs from a microcontroller or shift register connect directly to UDN2981A inputs, and each output drives one relay coil with the load return tied to a separate load ground pin. This separates sensitive logic ground from noisy inductive-return ground.
Recomendado
High-Side LED Array Driver
For common-cathode LED matrices, scoreboards, and bar-graph displays, the UDN2981A provides eight high-side current paths that source current to LED anodes while the cathodes share a common ground return. Each channel delivers up to 500 mA, sufficient for high-brightness LED strings with appropriate ballast resistors. The wide 80 V load rating accommodates long series-connected LED chains driven from 24 V or 48 V rails. Compared to discrete PNP transistors, the UDN2981A simplifies BOM and PCB layout while providing matched channel characteristics and integrated flyback protection for any inductive wiring.
Recomendado
Incandescent Lamp and 7-Segment Display Driver
Vintage-style incandescent lamp displays, Nixie tube anode drivers, and large 7-segment LED displays all benefit from the UDN2981A's high-side sourcing capability. Its 80 V load rating covers the 50-70 V anode supply typical of Nixie tubes, while the 500 mA per-channel rating easily handles incandescent filaments. The bipolar Darlington outputs offer low on-voltage drop at moderate currents, ensuring display brightness uniformity. Designers wire each display digit or lamp to one UDN2981A channel and multiplex by sequentially enabling logic inputs from the controller.
Recomendado
Unipolar Stepper Motor Winding Driver
In unipolar stepper motor designs the UDN2981A can source current to the center-tapped winding halves when paired with a complementary sink driver such as the ULN2803A or a discrete low-side switch. Each of the eight source outputs energizes one winding half, allowing control of two stepper motors (4-phase) or one 5-phase motor. The 80 V load rating accommodates higher-voltage stepper drives for increased torque and faster step rates. Built-in clamp diodes protect the IC from the back-EMF generated when winding current is interrupted.
Recomendado
Vintage PDP and Teletype Peripheral Driver
The UDN2981A was historically popular in PDP-11 and similar vintage computer interfaces, PiDP kits, and teletype current-loop peripherals. Its 80 V load supply tolerates the wide voltage swings of relay-based peripherals, and the 500 mA per-channel rating is sufficient for 20 mA teletype loops and small stepping relays. Hobbyists restoring vintage equipment or building replica machines (such as the PiDP-11) often seek the UDN2981A, but the modern Toshiba TBD62783A is a drop-in DMOS replacement offering cleaner switching transients. The through-hole 18-DIP package suits hand-wired reproduction projects.
Recomendado
Industrial 24V/48V Load Driver Card
Industrial automation cards often need to switch 24 V or 48 V solenoids, valves, lamps, and small motors from 5 V logic. The UDN2981A's 80 V load rating and 500 mA per-channel output are well matched to these requirements, and its built-in clamp diodes handle the inductive transients of 24 V relay coils and solenoid valves. Eight channels per IC allow a compact interface card design; multiple UDN2981A devices can be paralleled (with separate enable logic) to build 16, 24, or 32-channel cards. The separate logic-ground and load-ground pins simplify star-grounding in mixed-voltage systems.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para UDN2981A — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | UDN2981A-T | UDN2982A | UDN2984A | TBD62783A | A2982SLW |
|---|---|---|---|---|---|---|
| Brand | Allegro MicroSystems | Allegro MicroSystems | Allegro MicroSystems | Allegro MicroSystems | Toshiba | Allegro MicroSystems |
| Package | 18-DIP | 18-DIP (tape and reel) | 18-DIP - same | 18-DIP - same | 18-DIP - same | 20-SOIC (surface-mount) |
| Output Type | Bipolar Darlington source | Bipolar Darlington source | Bipolar Darlington source | Bipolar Darlington source | DMOS source | Bipolar Darlington source |
| Number of Channels | 8 | 8 | 8 | 8 | 8 | 8 |
| Load Supply Voltage (Max) | 80 V | 80 V | 50 V (family rating) | 80 V | 50 V | 50 V |
| Output Current per Channel | -500 mA | -500 mA | -500 mA | -1000 mA | -500 mA | -500 mA |
| Logic Compatibility | TTL, 5 V CMOS | TTL, 5 V CMOS | TTL, 5 V CMOS | TTL, 5 V CMOS | TTL, CMOS | TTL, CMOS |
| Built-in Clamp Diodes | Yes | Yes | Yes | Yes | Yes | Yes |
| Lifecycle Status | Obsolete / Last-time-buy | Obsolete | Obsolete | Obsolete | Active | Active |
Diferenciadores clave
- High-side (source) driver with 80 V load supply rating (frente a ULN2803A)
- Built-in clamp diodes for inductive loads (frente a Discrete PNP transistor array)
- Separate logic and load ground pins (frente a TBD62783A (DMOS source driver))
Notas de diseño
The UDN2981A in 18-DIP has a thermal resistance of approximately 90 C/W junction-to-ambient in free air. With all eight channels active at -500 mA and a 5 V drop, total dissipation reaches roughly 20 W - far exceeding the package rating. Always derate per-channel current when all channels are simultaneously ON. Estimated: theta_JA = 90 C/W, all-channels-on power = 8 x (VLOAD - VOUT_SAT) x IOUT.
Place a 0.1 uF ceramic bypass capacitor as close as possible to pin 10 (logic VCC) and a 10 uF or larger bulk capacitor on the load supply rail near the IC. Use wide PCB traces for the load outputs and load ground return to handle peak currents up to 4 A (8 channels x 500 mA) without significant voltage drop. Keep logic input traces short and away from the high-current load traces to minimize coupling.
Do not confuse the UDN2981A (source/high-side driver) with the ULN2803A (sink/low-side driver) - they are complementary devices with different output stage topologies and cannot be substituted. The 'A' suffix in UDN2981A indicates the 18-DIP through-hole package; the 'LW' suffix (e.g. UDN2982LW) indicates a 20-SOIC surface-mount package. When migrating between packages, verify pinout compatibility rather than assuming drop-in replacement.
The bipolar Darlington outputs have a saturation voltage of approximately 1.6 V at full load, which can dissipate significant power when driving low-voltage loads. For 3.3 V or 5 V loads, the Toshiba TBD62783A DMOS alternative offers lower on-resistance and cleaner switching. If the application requires fast switching (>1 kHz PWM), DMOS drivers are strongly preferred over the UDN2981A's slower bipolar outputs.
Información de cumplimiento
Allegro UDN2981A datasheet (10 pages, file size 180 KB) does not specify RoHS/REACH compliance in the verified web data. The part is widely reported as obsolete; consult Allegro directly for environmental compliance documentation. Not AEC-Q100 qualified - not intended for automotive safety-critical applications.
