When to use level shifter ?

Hello everyone,
i would like to know when exactly should a level shifter be used and not a normal voltage regulator ? is it when very small current is needed ?

thank you in advance

A voltage regulator is for power. When you have a 12V battery and an Arduino that requires 5V then you need a voltage regulator.

Level shifters are for signals. Like if a 5V Arduino has to talk to a 3.3V sensor.

MorganS:
A voltage regulator is for power. When you have a 12V battery and an Arduino that requires 5V then you need a voltage regulator.

Level shifters are for signals. Like if a 5V Arduino has to talk to a 3.3V sensor.

thank you for your reply MorganS, so I understand that if i have a wireless module that needs a 3.6V let's say i may use a level shifter to give it power ?

firashelou:
so I understand that if i have a wireless module that needs a 3.6V let's say i may use a level shifter to give it power ?

I think MorganS said exactly the opposite....

sayHovis:
I think MorganS said exactly the opposite....

So does it mean like i must put the level shifter between the arduino and the data pin of the sensor ?

Let’s put it this way. I have an HC-06 BT module- not on a breakout board, the actual smaller board with the half-round holes on the edge, I bought it by mistake.

  • The module itself requires 3V power, so I give it that from an Arduino 3V output.
  • The module’s Rx signal pin needs to be 3V, so I condition the Arduino 5V Tx output through a voltage divider
  • The module’s Tx pin is 3V so that can go into the Arduino Rx pin which is 5V, and 3V is enough to be a high.

sayHovis:
Let's put it this way. I have an HC-06 BT module- not on a breakout board, the actual smaller board with the half-round holes on the edge, I bought it by mistake.

  • The module itself requires 3V power, so I give it that from an Arduino 3V output.
  • The module's Rx signal pin needs to be 3V, so I condition the Arduino 5V Tx output through a voltage divider
  • The module's Tx pin is 3V so that can go into the Arduino Rx pin which is 5V, and 3V is enough to be a high.

ok so you mean you connected the TX of arduino to the level shifter and then to the module RX ?
because you said voltage divider which might means connecting resistors in a voltage divider way

I’m using the voltage divider as a level shifter… 5V in, 3V out at the middle.

sayHovis:
I’m using the voltage divider as a level shifter… 5V in, 3V out at the middle.

ok thank you :slight_smile:

I think you are confusing a level shifter with a dc to dc converter.
A dc to dc converter is for changing one power
voltage up or down to power something that uses
a different voltage whereas a level shifter is used for converting signal levels up or down.
Is that clear enough ?

Power is not signal in the same way a bulldozer is not a pair of tweezers!

Level shifters can translate a digital signal from one voltage level to the other. They can switch very fast (how fast will be stated in the data sheet). Often, they will need sources for both voltage levels. They mostly cannot provide excessive current (tens of mA is already a lot).
Voltage dividers will often work to shift to a lower voltage, but they have a (much higher) trade-off between current consumption and maximal signal speed.

A linear voltage regulator provides a constant voltage from a higher voltage source by "burning off" the power in the excess voltage. Switching it is comparably slow, because mostly, capacitors are involved. Consequently, you can only transmit slow digital signals. They can provide an amount of current that is usable to power things, how much stated in the datasheet. Current in = Current out. They can only reduce the voltage.

Switching regulators are similar, but they not burn the excess energy but convert it to a lower voltage level. Current in != Current out. They are also slow to change, tend to have more variation on the output voltage and may be inefficient under low load (i.e., drain your battery despite the fact that your device is in ultra low energy sleep). Step-up regulators can also increase the voltage.

I'm using the voltage divider as a level shifter.... 5V in, 3V out at the middle.

A voltage divider reduces the power considerably and therefore is not used for converting
power levels. It can be used in some cases as a signal level shifter.

Thank you gents for helping, i got the idea now it is for signal where we have signal voltage change