Allegro MicroSystems UDK2559LB

Overview

UDK2559LB from Allegro MicroSystems is a protected quad high-side power driver IC for industrial and automotive load control, featuring 700 mA per channel sink capability, 60 V output breakdown voltage, TTL/5 V CMOS-compatible inputs, and integrated thermal and overcurrent protection. It drives incandescent lamps, relays, solenoids, and unipolar stepper motors without external current-limiting resistors or flyback diodes.

For engineers reviewing the UDK2559LB datasheet, UDK2559LB pinout, UDK2559LB application, or UDK2559LB equivalent, key selection criteria include its –40°C to +125°C operating range, 16-pin SOICW package with fused leads, 1.0 A overcurrent trip threshold, and internal thermal limiting at ~165°C junction temperature.

Technical Context

The UDK2559LB integrates four independent bipolar NPN output stages with on-chip current-sense resistors and shunting transistors that activate at ~1.0 A to force linear operation and limit peak current. Each channel includes integral clamp diodes for inductive load suppression and sustains 40 V during overload conditions.

Its ENABLE input controls all four drivers simultaneously, and logic-level compatibility with both TTL and 5 V CMOS ensures direct interfacing with microcontrollers and FPGAs without level-shifting. The LB package uses internally fused pins (4 & 5, 12 & 13) to enhance thermal dissipation in surface-mount applications.

Key Specifications

Pinout & Package

UDK2559LB is housed in a 16-lead wide-body SOIC (SOICW) package (JEDEC MS-013 AA) with internally fused pins 4 & 5 and 12 & 13 for improved thermal performance. Pin 1 is marked with a notch or dot; pin numbering follows standard SOIC convention.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad high-side power driver applications.

Compared with UDK2559LB, UDK2559B-T offers better thermal resistance but requires through-hole assembly, while UDK2559EBTR-T delivers the lowest thermal resistance but demands larger PCB area and different packaging logistics - UDK2559LB balances SMT compatibility, thermal adequacy, and board space efficiency.

Availability

UDK2559LB is available at Aetrix Electronics and suitable for automotive lighting control, industrial relay interface, unipolar stepper motor driver, and heavy-duty load protection systems requiring stable component supply across extended temperature ranges.

Supply support for UDK2559LB 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

Allegro MicroSystems is a U.S.-based designer and manufacturer of high-performance magnetic sensors, power ICs, and motor driver solutions, headquartered in Worcester, Massachusetts.

The UDK2559LB belongs to Allegro's protected quad power driver family, engineered specifically for robust, fault-tolerant control of resistive and inductive loads in harsh automotive and industrial environments.

FAQ

What is the maximum continuous output current per channel for UDK2559LB?

The UDK2559LB supports 700 mA continuous sink current per channel under normal operating conditions. This rating assumes proper PCB thermal design - specifically, use of adequate copper pour on ground pins and adherence to JEDEC MS-013 AA pad layout guidelines. Exceeding this current continuously risks thermal shutdown or long-term reliability degradation, even though the overcurrent trip threshold is set at 1.0 A for transient fault protection.

Does UDK2559LB require external flyback diodes when driving relays?

No, UDK2559LB does not require external flyback diodes when driving relays or other inductive loads. Each output includes an integral clamp diode connected between the output pin and the K terminal (tied to VCC), which safely dissipates inductive energy during turn-off. This eliminates four discrete diodes from the BOM and reduces PCB layout complexity - confirmed in the Functional Block Diagram and Circuit Description sections of the official Allegro datasheet for UDK2559LB.

What is the operating temperature range specified for UDK2559LB?

The UDK2559LB is rated for an operating ambient temperature range of –40°C to +125°C. This extended range is explicitly defined for all UDK-prefix variants in the Absolute Maximum Ratings table and distinguishes UDK2559LB from UDN- and UDQ-series versions with narrower ranges. It qualifies the device for under-hood automotive applications and high-temperature industrial control environments.

How does the overcurrent protection mechanism work in UDK2559LB?

In UDK2559LB, overcurrent protection activates at approximately 1.0 A per channel. When triggered, the affected output stage enters linear mode instead of saturation, reducing output current to a level dependent on supply voltage and load resistance. If the condition persists, thermal-limiting circuits sense rising junction temperature and further decrease drive current. This two-stage response prevents immediate shutdown while maintaining partial functionality - a behavior documented in the "Fault Conditions" section of the UDK2559LB datasheet.

Is UDK2559LB pin-compatible with other members of the 2559B family?

UDK2559LB shares identical pin functions with UDK2559B-T and UDK2559EBTR-T, but physical pinouts differ due to package variations: LB (16-pin SOICW), B (16-pin DIP), and EB (28-pin PLCC) have distinct footprints and pin counts. While logic-level behavior and signal mapping are consistent across packages, PCB layout must be redesigned for each variant - UDK2559LB is not a drop-in replacement for the DIP or PLCC versions without mechanical and thermal redesign.