Why did you make it?

This circuit let for easy connecting electicaly not compatibile chips whatever interface they have. Low voltage system can be supplied from translator PCB, thus only one power supply is needed. In example PCB can be used to connect low voltage microcontrollers to 5V sensor with I2C, SPI or UART interface.

You are buying

• RT-NVT2008 with selected LDO - 1 pc.
• 2.54 pin headers - 2 pc.

PROPERTIES

• Wide range of the low side voltage
• Maximum high side input voltage: 5V
• Max. output current up to 150mA
• 1k resistors side B resistors - RB1..8
• Holes for 2.54 pin headers (CA,CB)
• Holes for ~AWG26 wires
• Detachable Wire strap slots
• 2x 2.54 pin headers

Product Description

This is a voltage level shifter/translator. It is capable of connecting the SPI/I2C communication buses or digital signals with different voltage standards. I.e. you can connect the 5V logic Arduino to 3.3V/1.8V logic sensors or to connect 3V3 IO of Digilent Analog Discovery to 1.8V/5V sensors.

This board has 8 bidirectional digital channels, SOT23-5 LDO voltage regulator for low side voltage and LEDs indicating supply voltages (low and high voltage). Voltage regulator can be used as power supply for connected sensor.

How it works?

Permitted voltage difference between connected devices is limited by equation (Input_B - Input_A)>= 1V. Where Input_B (Vref_B) is external supply voltage, Input_A (Vref_A) is the LDO regulator voltage.

Pull-up resistors

This board has an optional RA and RB 0402 pull-up resistors. More on choosing proper value of the pull-up resistors can be found in NVT2008 Datasheet. We assemble 1k Ohm RB resistors.

Low Voltage LDO regulator

RT-NVT2008 has fixed voltage regulator in the SOT23-5 package. You can switch freely LDOs according to the table 1.

Connecting module

How to choose correct voltage shifter

Connecting directly two systems supplied with different voltages can cause unpredictable behavior and in many cases damage lower voltage devices.

Voltage transltator is not necessary when connecting 3.3V output with 5V input or when 3.3V input is called 5V tolerant. In other cases it is demanded to use the voltage level shifter to ensure that the lower voltage device will not suffer from overvoltage damage.

Check in the chip or evaluation board datasheet what is the supply voltage of digital logic or what is the abolute maximum voltage rating. Choose voltage of the level shifter regulator to match system with the lower supply voltage.

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