Bi-Directional 5V to 3.3V 4-Channel Logic Level Converter User Guide

📋 Overview

This Bi-Directional 5V to 3.3V 4-Channel Logic Level Converter is a compact module that safely translates digital signals between 5V and 3.3V logic — in both directions, simultaneously, on the same channel. If you've ever tried to connect a 3.3V sensor or I2C module to a 5V Arduino and worried about frying your component, this little board is exactly what you need.

Most Arduino boards (Uno, Mega, Nano) operate at 5V logic. Many modern sensors, displays, and modules — especially those that communicate over I2C or SPI — run at 3.3V. Connecting them directly risks damaging the lower-voltage device. This module acts as a safe bridge between the two voltage worlds, using MOSFET-based circuitry to automatically detect signal direction and shift levels accordingly — no manual direction control needed.

With four independent channels, you can convert up to four signal lines at once. It's compatible with a wide range of logic voltages (1.8V, 2.8V, 3.3V, and 5V), making it useful beyond just 5V-to-3.3V conversions.

---

⭐ Key Features

• Bi-Directional Conversion: Shifts signals from 5V down to 3.3V AND from 3.3V up to 5V on the same channel — automatically.
• 4 Independent Channels: Convert up to four signal lines simultaneously (HV1–HV4 / LV1–LV4).
• Wide Voltage Compatibility: Works with 1.8V, 2.8V, 3.3V, and 5V logic devices.
• I2C & Arduino Ready: Designed specifically for I2C bus signals (SDA, SCL), but works with any digital signal.
• Auto Direction Detection: No direction-control pins needed — the MOSFET circuit handles it automatically.
• Compact & Easy to Use: Breadboard-friendly with included pin headers for quick prototyping.
• Protects Your Components: Prevents 5V signals from reaching 3.3V devices that could be damaged.

---

🎯 Applications

• Connecting 3.3V I2C sensors (temperature, humidity, pressure, IMU, etc.) to a 5V Arduino
• Interfacing 3.3V OLED or LCD displays with 5V microcontrollers
• Level-shifting SPI bus signals (MOSI, MISO, SCK, CS) between 5V and 3.3V systems
• Bridging a 5V Arduino with a 3.3V Raspberry Pi GPIO or other single-board computers
• Any general-purpose digital signal conversion between mismatched logic voltage systems
• Prototyping and breadboard development projects requiring mixed-voltage components

---

📊 Specifications

Parameter	Value
Number of Channels	4 (independent)
High Voltage (HV) Maximum	6V
Low Voltage (LV) Minimum	1.8V
Supported Logic Levels	1.8V, 2.8V, 3.3V, 5V
Signal Type	Digital only (not suitable for analog signals)
Direction Control	Automatic (no manual direction pin)
I2C Compatible	Yes
Dimensions	Approx. 15 × 13 mm (0.6 × 0.5 inches) L × W

---

📌 Pinout / Pin Diagram

The module has two rows of pins — one row for the high-voltage (5V) side and one for the low-voltage (3.3V) side.

High Voltage Side (HV — left row)

Pin Label	Description
HV	High Voltage power supply input — connect to your 5V supply
GND	Common ground — connect to the ground of both your 5V and 3.3V systems
HV1	Channel 1 signal pin — high voltage side
HV2	Channel 2 signal pin — high voltage side
HV3	Channel 3 signal pin — high voltage side
HV4	Channel 4 signal pin — high voltage side

Low Voltage Side (LV — right row)

Pin Label	Description
LV	Low Voltage power supply input — connect to your 3.3V supply
GND	Common ground — connect to the ground of both your 5V and 3.3V systems
LV1	Channel 1 signal pin — low voltage side
LV2	Channel 2 signal pin — low voltage side
LV3	Channel 3 signal pin — low voltage side
LV4	Channel 4 signal pin — low voltage side

Important: Both GND pins (HV side and LV side) must be connected to a common ground shared by your 5V and 3.3V systems. Without a common ground, the module will not work correctly.

---

🔌 Wiring / Connections

Wiring this module is straightforward. Follow these three steps:

Step 1 — Connect Power

• Connect the HV pin to your 5V supply (e.g., Arduino's 5V pin).
• Connect the LV pin to your 3.3V supply (e.g., Arduino's 3.3V pin, or your sensor's 3.3V rail).
• Connect both GND pins to the common ground of your circuit.

Step 2 — Connect Signal Lines

Each channel pairs a high-voltage signal pin with a low-voltage signal pin:

• HV1 ↔ LV1 — Channel 1
• HV2 ↔ LV2 — Channel 2
• HV3 ↔ LV3 — Channel 3
• HV4 ↔ LV4 — Channel 4

Connect the 5V device's signal to the HVx pin of the chosen channel, and the 3.3V device's signal to the corresponding LVx pin. The module automatically handles the signal direction — it doesn't matter which side is "sending" and which is "receiving."

Step 3 — You're Done!

You don't need to use all four channels. Leave unused channels unconnected.

Example — I2C connection (SDA & SCL only, using 2 channels):

• Arduino SDA → HV1 — Sensor SDA → LV1
• Arduino SCL → HV2 — Sensor SCL → LV2

Channels 3 and 4 are left unconnected.

---

🚀 Getting Started

The most common use case for this module is connecting a 3.3V I2C sensor or device to a 5V Arduino. Here's a complete walkthrough.

What You'll Need

• Arduino Uno, Nano, or Mega (5V logic)
• A 3.3V I2C sensor or module (e.g., BME280, MPU-6050 at 3.3V, OLED display, etc.)
• Bi-Directional Logic Level Converter module (this module)
• Breadboard and jumper wires

Wiring the I2C Bus

The I2C protocol uses two signal lines: SDA (Serial Data) and SCL (Serial Clock). Both need to be level-shifted.

Arduino Pin	Level Converter Pin	Level Converter Pin	3.3V Sensor Pin
5V	HV	LV	3.3V
GND	GND (HV side)	GND (LV side)	GND
SDA (A4 on Uno)	HV1	LV1	SDA
SCL (A5 on Uno)	HV2	LV2	SCL

Note for Arduino Uno users: The I2C pins are A4 (SDA) and A5 (SCL). On the Arduino Mega they are pins 20 (SDA) and 21 (SCL). On the Arduino Nano they share A4/A5 as well.

Verifying the Connection — I2C Scanner Sketch

Once wired up, upload this I2C Scanner sketch to your Arduino. It scans all possible I2C addresses and prints any detected devices to the Serial Monitor. If your sensor shows up, the level converter is working correctly.

#include <Wire.h>

void setup() {
  Wire.begin();
  Serial.begin(9600);
  while (!Serial);  // Wait for Serial Monitor to open
  Serial.println("I2C Scanner — scanning for devices...");
}

void loop() {
  byte error, address;
  int devicesFound = 0;

  for (address = 1; address < 127; address++) {
    Wire.beginTransmission(address);
    error = Wire.endTransmission();

    if (error == 0) {
      Serial.print("Device found at address 0x");
      if (address < 16) Serial.print("0");
      Serial.println(address, HEX);
      devicesFound++;
    }
  }

  if (devicesFound == 0) {
    Serial.println("No I2C devices found. Check wiring.");
  }

  Serial.println("---");
  delay(5000);  // Scan again every 5 seconds
}

Open the Serial Monitor (set to 9600 baud) and you should see the I2C address of your connected sensor printed. A typical I2C address looks like 0x76 or 0x68 depending on your device.

---

💡 Tips

Tip 1 — Digital signals only. This module shifts digital (high/low) signals. It cannot proportionally convert an analog voltage — for example, you cannot use it to scale a 5V analog sensor reading down to 3.3V for an ADC input. Use a resistor voltage divider for analog signals.

Tip 2 — I2C pull-up resistors. I2C requires pull-up resistors on the SDA and SCL lines. Many breakout boards for sensors include on-board pull-ups, so you may not need to add your own. If you're having communication issues, verify that pull-up resistors (typically 4.7kΩ) are present on both the HV side and LV side of the bus.

Tip 3 — Unused channels. You only need to use as many channels as your project requires. Unused channels can be left completely unconnected — there is no need to tie them to ground or any voltage.

Tip 4 — Common ground is essential. This is the most overlooked step. Both the 5V system and the 3.3V system must share a common ground connection. If they are powered from separate supplies, make sure their ground rails are connected together.

Tip 5 — Speed limitations. MOSFET-based level shifters like this module work well for I2C standard mode (100 kHz) and fast mode (400 kHz). For very high-speed signals (above 1 MHz), you may need a dedicated high-speed level shifter IC.

---

🛠️ Troubleshooting

No I2C devices detected in the Scanner sketch

• Double-check all wiring — verify HV goes to 5V, LV goes to 3.3V, and both GND pins are connected to common ground.
• Confirm the sensor is receiving power (check with a multimeter if needed).
• Make sure SDA and SCL are on the correct channels (HV1/LV1 and HV2/LV2, for example).
• Verify that I2C pull-up resistors are present on both the HV and LV sides of the bus.

Communication is unreliable or intermittent

• Check that your power supplies are stable and within spec (HV max 6V, LV min 1.8V).
• Inspect wiring for loose connections on a breadboard — this module is very small and the pins are closely spaced.
• Try adding small decoupling capacitors (0.1µF ceramic) near the HV and LV power pins to reduce noise.
• If operating at high I2C speeds (above 400 kHz), try reducing the clock speed — the MOSFET design has rise-time limitations.

Signal reads always HIGH or always LOW

• Verify the LV pin is connected to the correct voltage — not left floating.
• Confirm the ground connection is solid and shared between both sides.
• Check the sensor's own power supply — a sensor with no power will hold signal lines in an indeterminate state.

The module feels warm

• This module should not generate significant heat under normal operation. Warmth could indicate a wiring error — for example, if HV and LV are swapped, or if a signal line is shorted. Power down and recheck connections.

---

🏪 Where to Buy

This Bi-Directional Logic Level Converter is available from Envistia Mall

Bi-Directional 5V to 3.3V 4-Channel Logic Level Converter Module  →

• 📦 Fast US Shipping
• 🔄 Hassle-Free Returns
• 📧 Responsive Customer Support

---

Sold and supported by Envistia Mall. Ships from the USA. The manufacturer and Envistia LLC (dba Envistia Mall) are not responsible for any damages or losses resulting from the use of this product. Always follow proper electrical safety practices when working with electronic components. Specifications are based on manufacturer data and are subject to change without notice.