ULN2003A Technical Summary

ULN2003A - High-Voltage, High-Current Darlington Transistor Array

Overview

The ULN2003A is a high-voltage, high-current Darlington transistor array consisting of seven NPN Darlington pairs capable of handling load currents up to 500 mA per channel. This device features common-cathode clamp diodes for switching inductive loads, making it particularly suitable for interfacing between low-level logic circuitry and multiple peripheral power loads.

Designed for general-purpose switching applications, the ULN2003A offers compatibility with TTL, DTL, PMOS, or CMOS logic levels. Each channel is rated at 95V, with all outputs protected by suppression diodes for handling inductive load transients. The device is available in both dual in-line (DIP) and small-outline (SOIC) packages.

Features

Seven Darlington transistor arrays with common emitters
Output current rating of 500 mA per channel (600 mA peak)
Output voltage rating of 95V
Integrated suppression diodes for inductive load switching
Inputs compatible with various logic families:
- TTL (5V)
- DTL
- PMOS
- CMOS
Available in 16-pin configurations:
- Dual in-line plastic package (ULN2003A)
- Small-outline IC package (ULN2003L)
Inputs pinned opposite outputs to simplify board layout
High noise immunity

Applications

The ULN2003A finds extensive use in various electronic systems requiring high-current switching capabilities:

Relay drivers
Stepper motor controllers
Lamp drivers
Display drivers (LED, incandescent)
Logic buffers
Hammer drivers
Industrial control systems
Automotive applications
Peripheral drivers for microcontrollers

Electrical Characteristics

Absolute Maximum Ratings

Output Voltage (V_CE): 95V
Output Current (I_C): 500 mA per channel
Peak Output Current (I_C peak): 600 mA per channel
Input Voltage (V_IN): 30V
Power Dissipation (P_D): 2.25W (DIP), 1.4W (SOIC)
Operating Temperature Range: -20°C to +85°C
Storage Temperature Range: -65°C to +150°C

Electrical Specifications (T_A = 25°C unless otherwise noted)

Input Clamp Voltage (V_IK): 1.5V max at I_IN = 3.0 mA
Input Current (I_IN): 1.0 mA max at V_IN = 3.85V
Output Saturation Voltage (V_CE(sat)):
- 1.1V max at I_C = 200 mA, I_B = 0.25 mA
- 1.6V max at I_C = 350 mA, I_B = 0.5 mA
Output Leakage Current (I_CEO): 100 μA max at V_CE = 50V
Output Clamp Diode Forward Voltage (V_F): 1.6V max at I_F = 350 mA
Current Gain (h_FE): 1000 min at I_C = 350 mA

Package Information

16-Pin Dual In-Line Package (DIP)

Package Designation: ULN2003A
Package Type: PDIP-16
Dimensions: 19.30mm x 6.35mm (body)
Pin Spacing: 2.54mm (100 mil) between pins
Row Spacing: 7.62mm (300 mil) between rows
Lead Material: Copper alloy
Lead Finish: Matte tin
Moisture Sensitivity Level (MSL): MSL 1

16-Pin Small Outline IC Package (SOIC)

Package Designation: ULN2003L
Package Type: SOIC-16
Dimensions: 9.90mm x 3.90mm (body)
Pin Spacing: 1.27mm (50 mil)
Lead Pitch: 1.27mm
Lead Material: Copper alloy
Lead Finish: Matte tin
Moisture Sensitivity Level (MSL): MSL 1

Pin Configuration

The ULN2003A features the following pinout configuration:

Pin 1: Input 1
Pin 2: Input 2
Pin 3: Input 3
Pin 4: Input 4
Pin 5: Input 5
Pin 6: Input 6
Pin 7: Input 7
Pin 8: Ground
Pin 9: Common (for clamp diodes)
Pin 10: Output 7
Pin 11: Output 6
Pin 12: Output 5
Pin 13: Output 4
Pin 14: Output 3
Pin 15: Output 2
Pin 16: Output 1

Thermal Characteristics

Thermal Resistance, Junction-to-Air (θ_JA):
- DIP Package: 60°C/W
- SOIC Package: 95°C/W
Thermal Resistance, Junction-to-Case (θ_JC):
- DIP Package: 25°C/W
- SOIC Package: 40°C/W

Design Considerations

When implementing the ULN2003A in circuit designs, several important factors should be considered:

For inductive loads, connect the common pin (Pin 9) to the positive supply voltage to provide a return path for the clamp diodes
Ensure proper heat sinking when operating multiple channels simultaneously or at high currents
The device can drive loads directly connected to the positive supply (high-side switching) when