ULN2065B

ULN2065B Technical Summary

Overview

The ULN2065B is a high-voltage, high-current Darlington transistor array designed to interface between low-level logic circuitry and high-power peripheral devices. This component integrates multiple Darlington pairs with common emitters, enabling efficient switching of inductive loads such as relays, solenoids, and motors. Its robust design ensures reliable performance in industrial, automotive, and consumer applications where high-power switching is required.

Built with built-in suppression diodes for inductive load protection, the ULN2065B simplifies circuit design by reducing the need for external components. Its ability to handle high currents (up to 1.5A per channel) and voltages (up to 50V) makes it a versatile solution for driving various electromechanical devices.

Features

• High-Voltage Outputs: Capable of handling up to 50V, making it suitable for driving a wide range of loads.
• High-Current Sinking Capability: Supports up to 1.5A per channel, with a peak current of 2A.
• Integrated Suppression Diodes: Built-in clamp diodes for inductive load protection, eliminating the need for external flyback diodes.
• Multiple Darlington Pairs: Contains four independent Darlington transistor channels in a single package.
• TTL/CMOS Compatible Inputs: Directly interfaces with 5V logic, simplifying control circuit design.
• Wide Operating Temperature Range: Operates reliably from -20°C to +85°C, suitable for harsh environments.
• Common Emitter Configuration: Simplifies circuit design by allowing shared ground connections.

Applications

The ULN2065B is widely used in applications requiring high-power switching controlled by low-voltage logic signals. Key applications include:

• Relay and Solenoid Drivers: Provides the necessary current and voltage handling for electromechanical relays and solenoids.
• Motor Control: Used in driving small DC motors and stepper motors in automation systems.
• LED Display Drivers: Capable of driving high-current LED arrays in signage and display applications.
• Industrial Automation: Interfaces PLCs and microcontrollers with high-power actuators and sensors.
• Automotive Systems: Suitable for automotive control modules requiring robust switching capabilities.
• Consumer Electronics: Used in appliances and entertainment systems for power management.

Electrical Characteristics

The following table summarizes the key electrical specifications of the ULN2065B:

• Output Voltage (V_CE): 50V (max)
• Output Current (I_C): 1.5A per channel (continuous), 2A (peak)
• Input Voltage (V_IN): 5V (TTL/CMOS compatible)
• Input Current (I_IN): 1.5mA (typical)
• Saturation Voltage (V_CE(sat)): 1.1V (max) at I_C = 350mA
• Power Dissipation (P_D): 2.25W per channel (max)
• Turn-On Time (t_ON): 500ns (typical)
• Turn-Off Time (t_OFF): 250ns (typical)

Package Information

The ULN2065B is available in a 16-pin DIP (Dual In-line Package) and SOIC (Small Outline Integrated Circuit) package, providing flexibility for different PCB layouts. Key package details include:

• Package Type: 16-pin DIP or 16-pin SOIC
• Pin Pitch: 2.54mm (DIP), 1.27mm (SOIC)
• Mounting Style: Through-hole (DIP) or Surface-mount (SOIC)
• Dimensions (DIP): 19.3mm x 6.35mm x 4.57mm
• Dimensions (SOIC): 10.3mm x 7.5mm x 2.35mm
• Operating Temperature Range: -20°C to +85°C
• Storage Temperature Range: -55°C to +150°C

Functional Description

The ULN2065B consists of four Darlington transistor pairs, each with an input resistor and a suppression diode. The input resistor (typically 2.7kΩ) limits the base current, ensuring compatibility with TTL and CMOS logic levels. The suppression diodes are connected between each output and a common COM pin, which must be tied to the positive supply voltage when driving inductive loads.

When a logic high signal is applied to an input pin, the corresponding Darlington pair turns on, sinking current through the output pin to ground. The built-in diodes provide a path for the inductive kickback current when the transistor turns off, protecting the device from voltage spikes.

Design Considerations

When using the ULN2065B in a circuit, the following design considerations should be taken into account:

• Heat Dissipation: Ensure adequate heat sinking or PCB copper area to dissipate power, especially when driving multiple channels simultaneously.
• Inductive Load Protection: The COM pin must be connected to the positive supply voltage when driving inductive loads to activate the built-in suppression diodes.
• Input Current Requirements: While the input current is low, ensure the driving logic can supply sufficient current for all active channels.
• Parallel Operation: For higher current requirements, outputs can be paralleled, but derating may be necessary.
• PCB Layout: Keep high-current traces short and wide to minimize voltage drops and electromagnetic interference.

Conclusion

The ULN2065B is a versatile and robust solution for interfacing low-voltage logic circuits with high-power loads. Its integrated protection features, high current handling, and flexible packaging options make it an excellent choice for a wide range of industrial, automotive, and consumer applications. By following proper design practices, engineers can leverage the ULN2065B to create reliable and efficient switching circuits.