How to convert 5V peripherals to 3.3V microcontroller interfaces?

bigbat

How to convert 5V peripherals to 3.3V microcontroller interfaces? [Copy link]

Recently, I am working on a project where the sensor interface is a 5V UART TTL level interface, but the microcontroller is an NXP LPC824 3.3V UART interface. I know that it can be implemented with a chip like NLSX4378, but is there a solution to connect a suitable resistor in series with the interface? I hope that colleagues with practical experience can give some suggestions. Thank you for the friends who provide theoretical support!   

Angel_YY

The level conversion is usually realized by transistors. The specific schematic diagram is as follows:

tiankai001

You can use the circuit above, there are also voltage conversion chips, or use voltage regulator diodes

bigbat

Thank you all

bigbat

Some people say that it would be better to replace 8050 with MOS. I originally planned to use SN74LVC2T45, but it is a bit expensive

tiankai001

There was a post about this in the forum some time ago. You can take a look at 3.3V and 5V MCU communication circuit schematic diagram https://en.eeworld.com/bbs/thread-1059934-1-1.html Level conversion between 3.3V and 5V https://en.eeworld.com/bbs/thread-1059935-1-1.html

chunyang

The serial interface chip is generally a push-pull output type, and its output is interconnected with the MCU. It is theoretically possible to use resistors to divide the voltage or even directly connect resistors to limit the current, but whether the MCU can drive the serial port side requires careful reference to the device manual of the serial interface chip, and it is necessary to ensure that the level intersection is large enough. From the perspective of reliability, it is better to use a level conversion circuit.

bigbat

The New Year is coming soon, I wish you all a happy New Year and good health!

qwqwqw2088

5V and 3.3V level conversion is now mostly realized by chips, discrete components are troublesome