I bought a this voltage regulator . DC-DC 5v 8A voltage regulator. ıts supported 8-35V input voltage . And i want to use this with 12v power supply. But i searched on the internet . Nodemcu max amp is 800mA. This device can provide 2A per usb output if i will plug the nodemcu with usb cable this what happen ? Does it burn ? How can i drop the amps ? i want to use other 3 usb output with other devices sensors and screen .

Dc-Dc 5V 8A Voltage regulator

  • the 8 A is the maximum current that can be supplied before the power supply shuts down, or the output voltage starts to drop .... it does not mean that 8 amps will be pushed through any load ... the amount of current that 5 V can push through a load is dependent on the load resistance
    – jsotola
    Feb 8, 2020 at 23:19
  • @jsotola i understand thanks for your answer :) Feb 9, 2020 at 9:04

2 Answers 2


Generally, we specify DC power supplies as constant voltage sources. In order to do this, power supplies deliver more or less current as demanded by the load in an attempt to keep the voltage constant regardless of the load.

When a constant voltage DC power supply specifies a maximum current, it is saying the power supply can only maintain the specified voltage while the current demand is less than the specified maximum current.

To be clear, unless you need a constant current power supply, a power supply should be picked based on the required constant voltage. And the capacity of that power supply, usually measured in Amps, should exceed the maximum combined current demand of all connected devices (loads).

  • usb output is 5.2V which is its ok . But now I have a prototype for my project . i plug nodemcu to pc usb port and its provide 500mAh and its ok . but i want to connect 5v 2A usb port . I dont have too much electrical knowledge . I have difficulty about that. I just wonder nodemcu and other devices does it burn or not ? Feb 8, 2020 at 22:44
  • USB ports are regulated to be 5 volts or very close to 5 volts. You don't regulate both voltage and current. It is one or the other. Older USB ports are obliged to supply up to 500mA. Newer USB ports can supply more. But you only need to match voltages when talking about constant voltage power supplies. You do not match the current values. You only need to make sure you draw less current then the constant voltage power supply is rated for.
    – st2000
    Feb 8, 2020 at 23:45
  • For example, it is fine if you plug in a USB keyboard which expects 5 volts and draws only 15mA. As even the oldest USB computer ports supply 5 volts and have at least 500mA to offer. See, 5 volts == 5 volts and 15mA is < 500mA. So this should work fine.
    – st2000
    Feb 9, 2020 at 0:08
  • Ok. I understand now. more clear in my mind. Thank you for explanation and fast reply :) Feb 9, 2020 at 0:45

It will not burn. The nodeMCU will only "pull" the amount of current (amps) it needs.

  • Thanks man . I'm saying hypothetically. We will connect 5v 10A supply for nodemcu and nodemcu still pulls as much as it needs right ? Feb 8, 2020 at 22:36
  • Yes, it will only pull as much as it needs no matter how many amps the supply is capable of.
    – tavis
    Feb 9, 2020 at 5:12
  • Ok man thanks for your answer :) Feb 9, 2020 at 9:02

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