UDN2987LW - 8-Channel Source Driver, 350mA, 35V | Allegro
MPN: UDN2987LW ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.45 | $3.45 |
| 10 | $3.1 | $31.00 |
| 100 | $2.75 | $275.00 |
| 500 | $2.4 | $1,200.00 |
| 1,000 | $2.1 | $2,100.00 |
UDN2987LW Overview
As a power switch/driver IC, the UDN2987LW functions as a high-side driver that interfaces standard low-level logic (5 V TTL, Schottky TTL, DTL, PMOS, CMOS) with inductive loads such as relays, solenoids, motors, LEDs, and incandescent lamps. Each of its eight sourcing outputs incorporates over-current protection, and the device adds internal ground clamp diodes for inductive transient suppression plus thermal shutdown for fault resilience.
Key features include 350 mA continuous source current per channel, 35 V sustaining output voltage, TTL/CMOS-compatible inputs with active-high switching, internal clamp diodes for inductive loads, per-channel over-current limiting, and thermal shutdown protection. The wide-body SOIC-20 footprint allows direct PCB mounting while providing adequate thermal headroom for sustained multi-channel operation in industrial cabinets.
Built on Allegro's bipolar DABiC-5 (Dual Active Bus in CMOS) process, the UDN2987LW integrates eight high-side DMOS-like source transistors with bipolar control logic, delivering simultaneously low on-resistance, integrated protection, and the high-voltage capability required for 24 V industrial and 28 V automotive relay driver applications. Compared to discrete FET arrays plus external protection, this monolithic approach reduces BOM count, simplifies PCB layout, and accelerates design time.
Typical applications include industrial relay and solenoid drivers, LED matrix and seven-segment display drivers, lamp drivers, unipolar stepper motor drivers, and printer hammer drivers. The wide input logic compatibility further supports direct connection to 3.3 V microcontrollers when paired with a TTL-threshold interface.
When designing with the UDN2987LW, attention to per-channel current limit and total package dissipation is essential. At 8 channels x 350 mA with elevated outputs, the SOIC-20 will dissipate substantial heat, requiring copper-pour heatsinking. Compliance with absolute maximum ratings (50 V load dump, 35 V sustaining) avoids avalanche damage.
Drop-in alternatives for UDN2987LW — 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 UDN2987LW (same form factor and footprint) — differing in Package, Topology.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
UDN2987LW-6-T
✅ Drop-In📋 Reference alternative (not in catalog)
UDN2987LWTR-6-T
✅ Drop-In✓ In Stock
$1.38 / Unit
View Datasheet →UDN2987LW Maximum Ratings & Electrical Characteristics
| Device Type | 8-Channel Source Driver |
| Topology | High-side source driver |
| Number of Outputs | 8 |
| Output Current per Channel | 350 mA (continuous) |
| Sustaining Output Voltage | 35 V |
| Logic Input Compatibility | TTL, Schottky TTL, DTL, PMOS, CMOS |
| Input Logic Level | Active high (output ON when input high) |
| Over-Current Protection | Yes, per channel |
| Internal Clamp Diodes | Yes, for inductive loads |
| Thermal Shutdown | Yes |
| Turn-Off Delay (TPHL) | 200 ns typical (UDN2987LW-6 variant) |
| Supply Voltage Minimum (UDN2987LW-6) | 4.75 V |
| Package | 20-lead wide-body SOIC (SOICW-20) |
| Mounting Type | Surface Mount |
| Process Technology | Bipolar DABiC-5 |
| RoHS Status | Compliant |
UDN2987LW Pin Configuration
| Pin 1 | Input 1 — Logic input channel 1 (TTL/CMOS) |
| Pin 2 | Input 2 — Logic input channel 2 |
| Pin 3 | Input 3 — Logic input channel 3 |
| Pin 4 | Input 4 — Logic input channel 4 |
| Pin 5 | Input 5 — Logic input channel 5 |
| Pin 6 | Input 6 — Logic input channel 6 |
| Pin 7 | Input 7 — Logic input channel 7 |
| Pin 8 | Input 8 — Logic input channel 8 |
| Pin 9 | GND — Logic ground |
| Pin 10 | GND — Logic ground |
| Pin 11 | VCC — Logic supply (5 V) |
| Pin 12 | VBB — Load supply voltage |
| Pin 13 | Output 8 — Sourcing output channel 8 |
| Pin 14 | Output 7 — Sourcing output channel 7 |
| Pin 15 | Output 6 — Sourcing output channel 6 |
| Pin 16 | Output 5 — Sourcing output channel 5 |
| Pin 17 | Output 4 — Sourcing output channel 4 |
| Pin 18 | Output 3 — Sourcing output channel 3 |
| Pin 19 | Output 2 — Sourcing output channel 2 |
| Pin 20 | Output 1 — Sourcing output channel 1 |
Typical Applications
UDN2987LW is suitable for 6 applications: Industrial Relay and Solenoid Drivers, LED Matrix and Display Drivers, Unipolar Stepper Motor Drivers, Printer Hammer and Solenoid Drivers, Automotive Relay and Lamp Drivers, PLC and Industrial Automation Logic Outputs.
Industrial Relay and Solenoid Drivers
The UDN2987LW drives 24 V industrial relay coils and solenoid valves at up to 350 mA per channel across eight outputs. Internal clamp diodes suppress inductive back-EMF during turn-off, eliminating external flyback components. Per-channel over-current protection guards against shorted coils, and thermal shutdown protects the IC during sustained faults on multiple channels simultaneously.
Recommended
LED Matrix and Display Drivers
Eight sourcing outputs of 350 mA each make the UDN2987LW well-suited for common-anode LED matrix rows, seven-segment displays, and bar-graph indicators. TTL-compatible inputs interface directly with microcontroller GPIO. Active-high switching allows simple bit-banged multiplexing at refresh rates up to a few kHz, while internal current limiting prevents LED burnout from wiring faults.
Recommended
Unipolar Stepper Motor Drivers
For low-current unipolar stepper motors drawing under 350 mA per winding, the UDN2987LW acts as an 8-channel source array, replacing discrete transistor arrays with one integrated part. Each phase winding is driven directly from one output; combined with a complementary sink driver such as UDN2894L, full stepper control is achieved with minimal PCB area.
Recommended
Printer Hammer and Solenoid Drivers
Dot-matrix printers and industrial hammer actuators need fast, repeatable current pulses with back-EMF protection - exactly what the UDN2987LW supplies. Eight channels of 350 mA source drive multiple solenoids in parallel; the device's ~200 ns TPHL on the -6 variant enables sharp, repeatable hammer strikes without coil saturation. Internal clamping protects against solenoid inductive kickback.
Recommended
Automotive Relay and Lamp Drivers
The 35 V sustaining voltage rating comfortably covers 12 V and 24 V automotive and truck electrical systems, including the 50 V load-dump transient when paired with external TVS protection. The UDN2987LW drives relay coils, indicator lamps, and small motors at up to 350 mA per channel, with TTL/CMOS logic inputs that interface cleanly to body-control modules and BCM ASICs.
Recommended
PLC and Industrial Automation Logic Outputs
Programmable logic controllers (PLCs) require 24 V digital outputs to drive field devices. The UDN2987LW translates 5 V CMOS logic from the PLC's microcontroller into 24 V sourcing outputs at 350 mA per channel. Built-in over-current and thermal protection allow operation in cabinets with limited airflow, while internal clamp diodes simplify the BOM by removing external flyback components.
Recommended
Recommended Products Summary
Engineering reference data for UDN2987LW — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | UDN2987LW-6-T | UDN2987LWTR-6-T | UDN2987A |
|---|---|---|---|---|
| Package | SOICW-20 | SOICW-20 - same | SOICW-20 - same | DIP-20 - different package |
| Brand | Allegro MicroSystems | Allegro MicroSystems - same | Allegro MicroSystems - same | Allegro MicroSystems - same |
| Output Current per Channel | 350 mA | 350 mA | 350 mA | 350 mA |
| Sustaining Output Voltage | 35 V | 35 V | 35 V | 35 V |
| TPHL (Turn-Off Delay) | Longer (legacy) | 200 ns typical (improved) | 200 ns typical (improved) | Longer (legacy) |
| Over-Current Protection | Yes, per channel | Yes, per channel | Yes, per channel | Yes, per channel |
| Thermal Shutdown | Yes | Yes | Yes | Yes |
| Lifecycle Status | Not for New Design | Active | Active | Active |
Key Differentiators
- Integrated per-channel over-current protection (vs Discrete transistor arrays (e.g., discrete 2N4401 + fuse))
- Faster TPHL on the -6 variant (vs Original UDN2987LW)
- Surface-mount SOICW-20 package (vs UDN2987A in DIP-20 through-hole)
Design Notes
Estimated: at 8 channels x 350 mA with 24 V load supply and 5 V logic, total dissipation can reach 5-6 W in worst-case full-load scenarios. The SOICW-20 package requires substantial copper-pour heatsinking; a 1 sq-in copper area on a multi-layer PCB is recommended to keep theta_JA within safe limits and avoid triggering thermal shutdown prematurely.
Place VBB bypass capacitors (10 uF to 100 uF electrolytic in parallel with 0.1 uF ceramic) as close to the device pins as possible to suppress load-induced transients. Keep logic input traces short and away from the output traces to prevent cross-talk. Connect the exposed pad (if present on the SOICW variant) to a wide ground pour for optimal thermal performance.
Do not exceed 35 V sustaining voltage on the outputs; for automotive load-dump environments (up to 50 V transient), add an external TVS diode from VBB to ground. Avoid paralleling outputs to exceed the per-channel 350 mA rating - the over-current protection is per channel and does not sum across paralleled channels. The original UDN2987LW (non-6 suffix) is marked 'Not for New Design'; new layouts should use the -6 variant for longevity.
Compliance Information
RoHS compliant per Allegro product page. Not AEC-Q100 qualified - automotive designs should verify compliance via PPAP documentation with Allegro.
