Circuits / Power
AMS1117 module with an LED
A low-dropout regulator: 3.3 V out from 5 V in
Tap a part to see its voltages and currents. It is a model, not a measurement.
What do you need?
- Voltage regulator AMS1117-3.3Search on Amazon
- Resistor 220 ΩSearch on Amazon
- Red LEDSearch on Amazon
- Jumper wires × 2Search on Amazon
- BreadboardSearch on Amazon
How does an AMS1117 regulator make 3.3 V from 5 V?
The AMS1117-3.3 is a low-dropout linear regulator: it gives a steady 3.3 V from an input only a little higher. Here it runs from 5 V, the voltage of a USB port, and its 3.3 V output lights the LED through R1 (220 Ω) at about 7.2 mA, with 1.6 V across the resistor and 1.7 V across the LED. Low dropout means it keeps regulating with about 1.1 V of headroom, where a 7805 needs about 2 V. That is why it is the usual way to power an ESP32 or a sensor from 5 V. Like any linear regulator it turns the difference into heat: 1.7 V times the current. At a few milliamps that is nothing, but an ESP32 using Wi-Fi can draw a few hundred milliamps, and then the module gets warm.
Values from the Protoboard ISO simulation: a model, not a bench measurement.
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