Technical Summary: ULN2064B

ULN2064B High-Voltage, High-Current Darlington Transistor Array

Overview

The ULN2064B is a high-voltage, high-current Darlington transistor array designed to interface between low-level logic circuits and high-power peripheral devices. This monolithic integrated circuit features four Darlington pairs with common emitters and integral suppression diodes for inductive load driving. It is optimized for use in applications requiring high-voltage switching, such as relays, solenoids, lamps, and motor control.

Built with robust bipolar technology, the ULN2064B offers excellent performance in harsh environments while maintaining compatibility with standard TTL, CMOS, and PMOS logic levels. Each channel can handle load currents up to 1.5A, with a maximum output voltage rating of 50V, making it suitable for a wide range of industrial and automotive applications.

Features

Four high-voltage, high-current Darlington pairs in a single package
Output current rating of 1.5A per channel (3A peak)
Output voltage rating of 50V
Integrated suppression diodes for inductive load protection
Inputs compatible with TTL (5V), CMOS, and PMOS logic levels
Input resistors for direct interfacing with logic circuits
High noise immunity during switching operations
Common emitter configuration for simplified circuit design
Wide operating temperature range: -20°C to +85°C
Available in 16-pin DIP and SOIC packages

Applications

The ULN2064B finds use in numerous applications requiring high-current switching capabilities:

Industrial Control Systems

Relay and solenoid drivers
Stepper motor controllers
Industrial automation equipment
Programmable logic controller (PLC) interfaces

Automotive Electronics

Power window and seat control
Lighting systems
Fuel injection systems
Wiper motor control

Consumer Electronics

Appliance control circuits
Home automation systems
High-power LED drivers
Audio amplifier mute circuits

Computer Peripherals

Printer head drivers
Disk drive head positioning
Tape drive control

Electrical Characteristics

Absolute Maximum Ratings

Output Voltage (V_CE): 50V
Output Current (I_C) per Channel: 1.5A (continuous), 3A (peak)
Input Voltage (V_IN): 30V
Total Power Dissipation (P_D): 4W (DIP package), 2.25W (SOIC package)
Operating Temperature Range: -20°C to +85°C
Storage Temperature Range: -55°C to +150°C

Recommended Operating Conditions

Supply Voltage (V_CC): 5V to 25V
Input Voltage High (V_IH): 2.0V minimum
Input Voltage Low (V_IL): 0.8V maximum
Output Current (I_C): 0 to 1.5A per channel

Electrical Performance (T_A = 25°C unless otherwise specified)

Input Clamp Voltage (V_IK): 1.5V maximum at I_IK = -20mA
Output Saturation Voltage (V_CE(sat)): 1.1V typical at I_C = 350mA
Input Current (I_IN): 1.0mA maximum at V_IN = 5V
Output Leakage Current (I_CEO): 50μA maximum at V_CE = 50V
DC Current Gain (h_FE): 1000 minimum per Darlington pair
Turn-on Time (t_on): 0.5μs typical
Turn-off Time (t_off): 2.0μs typical

Package Information

16-Pin Dual In-Line Package (DIP)

Package Type: PDIP-16
Dimensions: 19.3mm x 6.35mm x 4.57mm (body)
Lead Pitch: 2.54mm
Lead Material: Copper alloy
Lead Finish: Matte tin
Mounting Style: Through-hole
Thermal Resistance (θ_JA): 50°C/W

16-Pin Small Outline Integrated Circuit (SOIC)

Package Type: SOIC-16
Dimensions: 9.9mm x 3.9mm x 1.75mm (body)
Lead Pitch: 1.27mm
Lead Material: Copper alloy
Lead Finish: Matte tin
Mounting Style: Surface mount
Thermal Resistance (θ_JA): 73°C/W

Design Considerations

Thermal Management

When operating at maximum current ratings, proper heat sinking or PCB copper area should be provided to maintain junction temperatures within safe limits. The DIP package offers better thermal performance than the SOIC version due to its larger size and through-hole mounting.

Input Circuitry

The ULN2064B includes 2.7kΩ input resistors, allowing direct connection to most logic families without additional components. For CMOS interfaces operating at voltages higher than 5V, external current-limiting resistors may be required.

Output Protection

The integrated clamp diodes provide protection against voltage spikes generated by inductive loads. For highly inductive loads, additional external protection components such as TVS diodes may be considered for enhanced reliability.

Parallel Operation

For applications requiring higher current than a single channel can provide, multiple outputs can be paralleled. However, current sharing resistors (0.1Ω to 0.5Ω) should be used to ensure balanced current distribution between channels.