Single Supply Logic Level Converter Hookup Guide

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Contributors: bboyho, LightningHawk
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Introduction

The Single Supply Logic Level Converter combines a boost converter (TPS61200), adjustable voltage regulator (MIC5205), and logic level translator (TXB0104) into one board. It provides 5V to the high side of the TXB0104 and the low side is programmable to 3.3V, 2.5V and 1.8V. The default low side voltage is 3.3V. With this device you can use your 5V microcontroller with 3.3V sensors and vice versa without the need for a second power supply!

SparkFun Logic Level Converter - Single Supply

SparkFun Logic Level Converter - Single Supply

PRT-14765
$14.95

What makes this logic level converter truly special is the fact that you can supply it with 3.3V and it will boost it to 5V - meaning you can use your 3.3V system, and convert directly to another 5V sensor - and even power your sensor or other board! We will use a 3.3V microcontroller and a 5V sensor for the example. However, you can use still this board with a 5V microcontroller and a 3.3V sensor.

Required Materials

To follow along with this project tutorial, you will need the following materials to level shift between a 3.3V microcontroller with a 5V sensor. You may not need everything, depending on what you have. Add it to your cart, read through the guide, and adjust the cart as necessary.

Tools

You will need a soldering iron, solder, and general soldering accessories.

Solder Lead Free - 100-gram Spool

Solder Lead Free - 100-gram Spool

TOL-09325
$7.95
7
Weller WLC100 Soldering Station

Weller WLC100 Soldering Station

TOL-14228
$44.95

Suggested Reading

If you aren’t familiar with the following concepts, we recommend checking out these tutorials before continuing.

How to Solder: Through-Hole Soldering

This tutorial covers everything you need to know about through-hole soldering.

How to Use a Breadboard

Welcome to the wonderful world of breadboards. Here we will learn what a breadboard is and how to use one to build your very first circuit.

Installing Arduino IDE

A step-by-step guide to installing and testing the Arduino software on Windows, Mac, and Linux.

Logic Levels

Learn the difference between 3.3V and 5V devices and logic levels.

How to Install FTDI Drivers

How to install drivers for the FTDI Basic on Windows, Mac OS X, and Linux.

Using the Arduino Pro Mini 3.3V

This tutorial is your guide to all things Arduino Pro Mini. It explains what it is, what it's not, and how to get started using it.

Hardware Overview

Before we discuss hooking up the breakout, let’s go over some of the features of this board.

Top View of Single Supply Logic Level Converter

Pinout

The following table describes the pins that are broken out.

PinDescription
VINInput Supply Voltage (3V - 5.5V)
GNDGround
VOUT, 5VBoost Converter's Voltage Output Set to 5V
VOUT, 3.3VRegulated Voltage Output Set to 3.3V
(can be adjusted depending on resistor)
A1-A4Programmable VCCA Port for Lower TTL Logic Levels - Default = 3.3V
B1-B4VCCB Port for Higher TTL Logic Levels - Set to 5V

Logic Level Shifter

The Single Supply Logic Level Converter breaks out Texas Instrument's TXB0104 module. The TXB0104 is a 4-bit, noninverting, bi-directional voltage-level translator with automatic direction sensing.

TXB0104 Highlighted on the board with Low and High Side TTL pins

Each pin on this module is broken out for you to easily access ports A and B. Port A (A1-A4) is for low side TTL levels. This device’s VCCA is set to 3.3V by default but can easily be programmable with a resistor to 2.5V and 1.8V. Port B (B1-B4) is for high side TTL levels. VCCB is hard wired to 5V. VCCA should not exceed VCCB. Depending on which voltage is chosen for VCCA the data rate may vary.

Adjusting the Lower Voltage Side (i.e. VCCA)

To adjust the reference voltage for the low side, you will need an associated resistor value to adjust the MIC5205’s output voltage. Below is a table of calculated resistor values that can be used. For more information, check out equation 4-7 on page 11 of the datasheet.

VCCAResistor Value
3.3VDefault = 13kΩ
2.5V22kΩ
1.8V49kΩ

Simply remove the default surface mount resistor with a blob of solder so that heat can be transferred to both terminals. Once heated, the surface mount resistor can be removed with tweezers or a gentle sweep of a soldering iron. Once removed, a resistor of your choice can be used to adjust the VCCA's reference voltage.

Resistor to Modify When Adjusting the Low Side Voltage Reference Pin

Power Supply and Voltage Regulator

The TPS61200 buck/boost converter on the Single Supply Logic Level Converter takes an input between 3V - 5.5V (most likely from your microcontroller’s VCC pin) and regulates it to 5V. This output is also connected to the high side on VCCB for reference.

Input Voltage Pins

The output current of the TPS61200 depends on the input to output voltage ratio. The TPS61200 provides output currents up to 600 mA at 5V. The maximum average input current is limited to 1.5A. For more information, check out the datasheet.

Components Highlighted on the Single Supply Logic Level Converter for a Buck/Boost Voltage of 5V

The regulated 5V is then further regulated to 3.3V, which is connected to the low side on VCCA for reference. There is an option to reprogram VCCA's voltage using an external PTH resistor as explained earlier.

Components Highlighted on the Single Supply Logic Level Converter for Regulated 3.3V

Timing Requirements

Not all logic level converters are the same! Compared to the lower cost bi-directional logic level converter with BSS138, the single supply logic level converter with TXB0104 is able to achieve higher data rates. The speed is dependent on the reference voltage that is used for the low side voltage on VCCA. This is indicated by the table below and was taken from the datasheet. For more information, check out page 8 of the datasheet.

VCCAData RatePulse Duration
1.5V40 Mbps25 ns
1.8V60 Mbps17 ns
2.5V100 Mbps10 ns
3.3V100 Mbps10 ns

Hardware Hookup

Grab some straight header pins, break the pins apart, and solder them to the single supply logic level converter.

Soldered Single Supply Logic Level Converter

This would also be a good time to solder headers to the 3.3V/8MHz Arduino Pro Mini if you have not already done so!

Soldered Arduino Pro Mini

Circuit Diagram

Ready to start hooking everything up? Check out the circuit diagram below to connect the components together.

Fritzing Diagram of Example Circuit to Translate 5V Sensor Data to a 3.3V Arduino Microcontroller

Having a hard time seeing the circuit? Click on the image for a closer look.

Example Code

Note: This example assumes you are using the latest version of the Arduino IDE on your desktop. If this is your first time using Arduino, please review our tutorial on installing the Arduino IDE.

The single supply logic level converter can be used to shift data in either direction. In this example, we are going to shift levels from a 3.3V Arduino microcontroller and a 5V sensor.

Level Shifting Between a 3.3V Microcontroller w/ 5V Sensor

Copy the code below and paste it into the Arduino IDE. Since we are using an Arduino Pro Mini 3.3V/8MHz, make sure that you are selecting the correct board. Additionally, make sure to have the correct COM port selected when uploading. When ready, upload the example code!

language:c
/*
Single Supply Logic Level Converter Hookup Guide

This project will beep continuosly with a frequency proportional
to distance. As objects get closer, the beep gets faster.

Hardware:
 HC-SR04 Ultrasonic Sensor
 Arduino Pro Mini 3.3V/8MHz
 SparkFun Single Supply Logic Level Converter
 Piezo Buzzer

*/


#define TRIG_PIN 10
#define ECHO_PIN 11
#define Beep 3

void setup() {
  Serial.begin (9600);
  pinMode(TRIG_PIN, OUTPUT);
  digitalWrite(TRIG_PIN, LOW);
  pinMode(Beep, OUTPUT);
}

void loop() {
  unsigned long t1;
  unsigned long t2;
  unsigned long pulse_width;
  float cm1;


  // Hold the trigger pin high for at least 10 us
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // Wait for pulse on echo pin
  while (digitalRead(ECHO_PIN) == 0 );

  // Measure how long the echo pin was held high (pulse width)
  // Note: the micros() counter will overflow after ~70 min
  t1 = micros();
  while (digitalRead(ECHO_PIN) == 1);
  t2 = micros();
  pulse_width = t2 - t1;

  // Calculate distance in centimeters.
  cm1 = pulse_width*0.034/2;
  if (cm1 >= 200 || cm1 <= 0){
    Serial.println("Out of range");
  }
  else {
    Serial.print(cm1);
    Serial.println(" cm");

    tone(Beep,528);
    delay(100);
    noTone(Beep);
    delay(cm1);


  }
}

After uploading, place your hand in front of the ultrasonic sensor. When your hand is within a certain range, the buzzer will begin beeping! As you move your hand toward the sensor, the buzzer will beep faster. Moving your hand away from the sensor will slow down the beeping until you are out of range.

Circuit for shifting logic between a 3.3V microcontroller and 5V sensor

Resources and Going Further

Now that you know how to get the Single Supply Logic Level Converter up and running, it’s time to incorporate it into your own project!

For more on the Single Supply Logic Level Converter, check out the links below:

Need some inspiration for your next project? Check out some of these related tutorials:

PCA9306 Level Translator Hookup Guide

A quick primer to get you going with the PCA9306 Logic Level Converter.

Bi-Directional Logic Level Converter Hookup Guide

An overview of the Bi-Directional Logic Level Converter, and some example circuits to show how it works.