ULN2003AU is a monolithic high-voltage and high-current Darlington transistor array developed by Slkor Micro. The device integrates seven groups of NPN Darlington pairs internally, with common-cathode clamp diodes for inductive load switching scenarios. Each single channel can deliver maximum collector current output of 500mA. A 2.7kΩ series base resistor is built-in for each input channel, enabling direct connection with TTL and 5V CMOS logic levels. It comes in SOP-16 package, while ULN2003AE of the same series adopts DIP-16 package. This component is widely used for driving relays, indicator lamps, display modules and other loads.

1. Core Product Parameters

Absolute Maximum Ratings (Ta=25℃)

1. Collector-Emitter Voltage: 50V
2. Input Voltage: 30V
3. Peak Collector Current for single channel: 500mA
4. Total Emitter-terminal Current: 500mA
5. Power Dissipation: 950mW at ambient temperature 25℃; 495mW at ambient temperature 85℃
6. Operating Temperature Range: -40℃ ~ +85℃
7. Storage Temperature Range: -65℃ ~ +150℃

Electrical Characteristics (Ta=25℃)

1. On-state Input Voltage: the maximum value is 2.4V, 2.7V and 3V under different collector-current test conditions
2. Collector-Emitter Saturation Voltage: typical value ranges from 0.9V to 1.2V according to different input current and collector current, with maximum value no higher than 1.6V
3. Collector Cutoff Current: maximum 50μA at room temperature, maximum 100μA at 70℃
4. Clamp Diode Forward Voltage: typical value 1.7V, maximum 2V
5. Off-state Input Current: typical value 65μA, minimum value 50μA
6. Input Current: ranging from 0.95mA to 1.35mA when input voltage equals 3.85V
7. Clamp Reverse Current: maximum 50μA at room temperature, maximum 100μA at 70℃
8. Input Capacitance: typical value 15pF, maximum 25pF
9. Propagation Delay for high-to-low and low-to-high output: maximum 1μs for both conditions

2. Core Product Features

1. Rated collector current of each single output channel reaches 500mA, and maximum output withstand voltage is 500V. Multiple Darlington channels can be paralleled to achieve higher output driving current.
2. A 2.7kΩ series base resistor is integrated inside every channel. Direct compatibility with TTL and 5V CMOS logic devices is achieved without extra external current-limiting resistors.
3. Internally equipped with common-cathode clamp diodes. For inductive loads such as relay coils, the diodes absorb reverse electromotive force generated at turn-off moment and protect the chip from damage of reverse high voltage.
4. Two package options are available. ULN2003AE uses DIP-16 through-hole package and ULN2003AU uses SOP-16 surface-mount package to fit different PCB assembly processes.
5. The input supports multiple types of logic level signals. Low signal propagation delay provides favorable switching response performance.

3. Main Application Fields

1. Relay driving circuits, controlling on-off state of relay coils with small-amplitude logic signals.
2. Driving electromagnetic actuators such as print hammers.
3. Driving indicator lamps and incandescent lamp loads.
4. Driving display devices including LED and gas discharge displays.
5. Line driving and logic signal buffer circuits.

4. Suggestions for Engineering Design

1. When driving inductive loads, make full use of the internal common-cathode clamp diodes. Connect COM pin to the positive terminal of load power supply to release reverse energy produced by inductors at power-off, and prevent component damage caused by reverse voltage.
2. When paralleling multiple channels to expand output current capacity, refer to component characteristic curves. Pay attention to restrictions on maximum allowable output current brought by duty cycle and number of simultaneously-enabled channels. Do not simply add up rated current of single channels.
3. Pay attention to power dissipation of the device. The maximum allowable power dissipation decreases when ambient temperature rises. Sufficient power margin shall be reserved for high-temperature working conditions.
4. No external base resistor is required for input signals directly sourced from TTL or 5V CMOS chips. For input of other voltage level standards, evaluate input current to avoid input current overflow.
5. Keep the emitter pin reliably connected to ground. All voltage parameters take emitter potential as reference benchmark.
6. Take output saturation voltage into consideration during circuit design. Include saturation voltage drop in load loop voltage budget to avoid insufficient actual working power of loads.

5. Product Summary

ULN2003AU is a seven-channel integrated Darlington transistor array. Darlington amplifying transistors, base current-limiting resistors and protective clamp diodes for inductive loads are fully integrated inside the chip, which greatly reduces the quantity of peripheral components. Compatible with conventional digital logic outputs, it amplifies weak logic signals to drive various low-and-medium power resistive and inductive loads. The SOP-16 surface-mount package suits high-density PCB layout, while the through-hole variant fits manual soldering and prototype debugging. It serves as a widely-adopted load-driving component in industrial control and household appliance circuits.

About Slkor：

Slkor has research and development offices in Busan, South Korea, Beijing, China, and Suzhou, China. Most of the wafer manufacturing and packaging and testing are carried out within China. The company employs and collaborates with individuals and organizations worldwide, with a laboratory for product performance and reliability testing and a central warehouse located at its headquarters in Shenzhen. Slkor has filed for over a hundred invention patents, offers more than 2,000 product models, and serves over ten thousand customers globally. Its products are exported to countries and regions including Europe, the Americas, Southeast Asia, and the Middle East, making it one of the rapidly growing semiconductor companies in recent years. With well-established management systems and streamlined workflows, Slkor has rapidly enhanced the brand awareness and reputation of its "SLKOR" brand through its outstanding quality and standardized services. Its product range includes three major series: diodes, transistors, and power devices, with recent introductions of new products such as Hall elements and analog devices, expanding its presence in sensors, Risc-v microcontrollers, and other product categories.

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