4-channel BSS138 logic level converter board with two loose 6-pin headers, component side up

4-Channel Logic Level Converter BSS138 - Bidirectional 3.3V to 5V

$2.59 NZD
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SKU: MOD-LLC-4CH-BSS138

4-Channel Logic Level Converter BSS138 - Bidirectional 3.3V to 5V

$2.59 NZD
Availability:
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A 4-channel bidirectional logic level converter for joining 3.3V and 5V boards, such as a 5V Arduino Uno and a 3.3V sensor, or an ESP32 and a 5V module. Each channel uses a BSS138-type MOSFET with 10 kΩ pull-ups on both sides, so it shifts I2C, UART serial and slow SPI signals in either direction. You power the low side (LV) from the lower voltage and the high side (HV) from the higher one. Two 6-pin headers come loose in the bag.

Specifications

Channels4, each bidirectional
TransistorsBSS138-type N-channel MOSFET (marked J1), one per channel
Pull-ups10 kΩ on every signal pin, both sides
Low side (LV)1.8 to 3.6V, must be lower than HV
High side (HV)3.3 to 5.5V
Good speedsI2C 100 kHz (400 kHz on short wires), UART to 115200 baud, SPI to about 1 MHz
Not suited toWS2812 LED data, fast SPI displays, or driving relays, motors and LEDs
PinsHV, LV, 2 x GND, HV1 to HV4, LV1 to LV4, 2.54 mm pitch
Board sizeAbout 14.4 x 12.4 mm, no mounting holes

Datasheets

What's in the box

1×
4-channel logic level converter board

Header holes empty, ready to solder.

2×
6-pin straight male headers, 2.54 mm

Loose. Jumper wires and the boards you are joining are not included.

Great for

Read a 3.3V BMP280 sensor from a 5V Uno
Drive a 5V I2C LCD backpack from an ESP32
Connect an ESP32 to a 5V serial GPS or module
Read a 5V HC-SR04 echo pin on a 3.3V board
Join a Raspberry Pi to 5V I2C devices
Run slow SPI between 3.3V and 5V parts

Wiring & getting started

  1. Fit the headers

    Solder the two 6-pin headers, long pins down, to plug the board into a breadboard or onto female jumper wires.

  2. Power both sides

    HV to the higher supply (5V), LV to the lower one (3.3V), and GND to the ground of both boards. Both HV and LV must be connected or nothing converts.

  3. Wire the signals

    Use the same channel number on each side: for an Uno and a 3.3V I2C sensor, A4 (SDA) to HV1 and LV1 to the sensor's SDA, then A5 (SCL) to HV2 and LV2 to SCL. The BMP280 3.3V sensor and Dupont jumper wires suit this.

  4. Check it works

    Upload the I2C scan sketch from the Quick Start and open the Serial Monitor at 9600 baud. The sensor's address prints, for example 0x76.

Frequently Asked Questions

Answers to the questions buyers ask most.

Will it let my 5V Arduino talk to a 3.3V sensor or ESP32?
Yes, that is its job. Connect HV to the 5V board's 5V pin, LV to the 3.3V side's 3.3V supply and join the grounds. Signals on HV1 to HV4 then appear at 3.3V on LV1 to LV4, and signals from the 3.3V side appear at 5V on the HV side.
Which way round does it go?
LV must go to the lower voltage and HV to the higher one. Both must be connected, because each channel takes its high level from those two pins. With LV and HV swapped, or one left off, the signals pass through unconverted or not at all.
How fast can it go?
I2C at 100 kHz is reliable, and 400 kHz works over short wires when the bus has its own pull-ups too. UART serial is fine up to 115200 baud, and SPI up to about 1 MHz. The high level comes from 10 kΩ pull-ups, so rising edges are slow. For fast SPI displays, SD cards or WS2812 LED data, use a buffer-type level shifter instead.
Do I need to add pull-up resistors for I2C?
No. Every signal pin already has a 10 kΩ pull-up on both sides, so SDA and SCL need nothing extra. Pull-ups already on your sensor board can stay.
Can it switch a relay, LED or motor?
No. It shifts logic signals only. A high output can supply only about 0.5 mA through its pull-up, which is enough for a logic input but not for a relay, LED or motor driver input that needs current.
How many signals can it handle?
Four, one per channel, and each works in both directions. I2C needs two (SDA and SCL), UART needs two (TX and RX), and SPI usually needs four (SCK, MOSI, MISO and CS). Unused channels can be left unconnected.
Do I need to solder it?
Yes. The board comes with its holes empty and two loose 6-pin headers. Solder them long pins down to use the board on a breadboard or with female jumper wires, or solder wires straight to the holes.

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