UL2003APG

Ahhh yes! 😄 The ULN2003APG — one of the most classic “power driver” ICs in hobby electronics. If you’ve ever controlled motors, relays, or LEDs from a microcontroller, you’ve probably used (or needed) this chip! ⚡🤖

📦 ULN2003APG – Product Description

The ULN2003APG is a high-voltage, high-current Darlington transistor array IC.

It’s basically 7 Darlington pairs in a single IC, designed to interface low-voltage logic (like 5 V from Arduino, PIC, or 8051) with high-voltage/high-current loads such as:

Relays

Stepper motors

LEDs

Solenoids

Lamps

It handles up to 500 mA per channel and 50 V max.

The “APG” suffix usually refers to the PDIP-16 package (through-hole version).

✨ Key Features

✅ 7-channel Darlington array (7 drivers in one IC)
✅ Handles 500 mA per channel
✅ Maximum voltage: 50 V
✅ Open-collector outputs (can sink current)
✅ Internal flyback diodes (for inductive loads)
✅ TTL/CMOS compatible input
✅ Easy interface to microcontrollers

📊 Electrical Specifications
Parameter Typical / Max Value
Output voltage 50 V max
Output current 500 mA per channel
Input voltage (logic) 5 V typical (TTL/CMOS compatible)
Input current ~1.35 mA at 5 V
Total package dissipation ~2 W
Saturation voltage ~1 V @ 350 mA
Package 16-pin PDIP (ULN2003APG)
Temperature range 0 °C – 70 °C (commercial)
🔌 Pin Configuration (PDIP-16)
ULN2003APG
┌─────────────┐
1 IN1 COM 16
2 IN2 OUT7 15
3 IN3 OUT6 14
4 IN4 OUT5 13
5 IN5 OUT4 12
6 IN6 OUT3 11
7 IN7 OUT2 10
8 GND OUT1 9
└─────────────┘

Pin functions:

IN1–IN7 → logic inputs from MCU

OUT1–OUT7 → outputs to load (relays, motors, LEDs)

COM → common for flyback diodes (connect to +V for inductive loads)

GND → ground

⚙️ How It Works

Logic input HIGH → corresponding Darlington pair conducts

Output sinks current from load to GND

Internal flyback diodes protect IC from voltage spikes from inductive loads

Can switch up to 50 V and 500 mA per channel

💡 Perfect for microcontroller-to-motor/relay interface.

🛠️ Typical Applications

Stepper motor control (unipolar stepper motors)

Relay driving circuits

LED matrices

Solenoid or small actuator control

Arduino/Raspberry Pi motor shields

💡 Pro Tips
✅ Flyback protection

Always connect COM pin to +V if switching relays/inductive loads.

✅ Parallel channels

Can parallel outputs for higher current, up to ~1 A (careful with heating).

✅ Microcontroller friendly

Inputs draw very little current (~1 mA) → perfect for 5 V logic.

✅ Heatsink

If driving many channels at high current, consider cooling — otherwise, safe under 500 mA per channel.

✅ Quick Summary

ULN2003APG = 7-channel Darlington driver IC

Use it when you need:
✔ Control relays from Arduino/PIC/MCU
✔ Drive stepper motors
✔ Switch high-voltage/high-current loads with logic-level signals
✔ Minimal external components