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# LM2596 Buck Converter Module

The classic blue step-down module: up to 40 V in, an adjustable output from a multi-turn trimmer, built on TI's 3 A LM2596.

Source page: https://www.tinkered.ai/components/lm2596-buck-module
Datasheet: https://www.ti.com/lit/ds/symlink/lm2596.pdf

## In short

The LM2596 buck module is a step-down DC-DC converter built on TI's LM2596, a 150 kHz switching regulator rated for a 3 A load and inputs up to 40 V (TI LM2596 datasheet, p. 1). Wire the supply to IN+ and IN-, turn the trimmer while measuring OUT+ to set the voltage, then connect the load to OUT+ and OUT- with a ground shared with your microcontroller. The adjustable chip regulates from its 1.23 V feedback reference up to 37 V, always below the input (pp. 1, 6).

The LM2596 buck module is a small blue board that steps a higher DC voltage down to a lower one efficiently. It carries an LM2596S-ADJ regulator, the inductor, Schottky catch diode and capacitors its datasheet circuit needs, and a multi-turn trimmer that sets the output. Four terminals bring out IN+ and IN- at one end and OUT+ and OUT- at the other, with IN- and OUT- joined on the board.

The LM2596 is a monolithic step-down switching regulator from Texas Instruments. It switches at a fixed 150 kHz, drives a load of up to 3 A, accepts 4.5 V to 40 V on its input, and in its adjustable version sets an output from 1.2 V to 37 V through a 1.23 V feedback reference (TI LM2596 datasheet, pp. 1, 5, 6). It includes current limiting and thermal shutdown, and an ON/OFF pin that drops its standby current to about 80 µA (pp. 1, 4).

Because it switches rather than burning the difference as heat, a buck converter suits large drops: TI's test circuits reach 73 % efficiency at 3.3 V out from 12 V, 80 % at 5 V from 12 V, and 90 % at 12 V from 25 V, all at 3 A (p. 6). That makes the module a staple for powering servos, LED strips and microcontroller boards from 9 V to 24 V batteries and adapters.

## Agent rules

Follow these when you wire this part or write code for it.

- Do: IN+ from a supply of 4.5-40 V: a 9 V or 12 V battery, a 4xAA pack (6 V: enough for 3.3 V out, short of 5 V), a 12 V adapter. Never from a board's output pin.
- Do: IN− to the supply's −, and the circuit's ground to OUT− (the same copper): a board that drives parts powered by the buck shares that ground.
- Do: Set vout to what the load takes: 5 for 5 V parts and servos; 3.3 for 3.3 V parts; 12 for 12 V strips or fans.
- Do: Feeding a board, through its input pin: an Uno's or Nano's VIN at 7-12 V (vout=9); an ESP32 DevKit's VIN or a Pico's VSYS at 5 V (vout=5).
- Do: Servos, motors, LED strips, relays: power them from the buck, not from the board's 5V pin (USB and the board's regulator cannot give the current).
- Never: No buck without vout= when anything with a voltage limit is on its output.
- Never: No IN+ above 40 V or below 4.5 V; no output set above IN+ minus 1.5 V.
- Never: No output on a 3.3 V part while it is set higher; no output on a board's 5V or 3V3 pin.

## Pinout

| Pin | Function | Type |
| --- | --- | --- |
| VIN | IN+ (4.5-40 V in) | power in |
| GND_IN | IN- (ground) | power in |
| VOUT | OUT+ (adjustable out) | power out |
| GND_OUT | OUT- (ground) | power in |

## Wiring

### Arduino Uno

| LM2596 Buck Converter Module | Arduino Uno | Note |
| --- | --- | --- |
| GND_OUT | GND |  |

### ESP32 DevKit V1

| LM2596 Buck Converter Module | ESP32 DevKit V1 | Note |
| --- | --- | --- |
| GND_OUT | GND |  |

### Raspberry Pi Pico

| LM2596 Buck Converter Module | Raspberry Pi Pico | Note |
| --- | --- | --- |
| GND_OUT | GND |  |

## Specifications

| Spec | Value | Source |
| --- | --- | --- |
| Input voltage (chip) | 4.5 V to 40 V operating; 45 V absolute maximum | TI LM2596 datasheet (SNVS124G), p. 5 |
| Output voltage (adjustable) | 1.2 V to 37 V, ±4 % over line and load | TI LM2596 datasheet, p. 1 |
| Feedback reference | 1.23 V typical (1.193 V to 1.267 V at 25 °C) | TI LM2596 datasheet, p. 6 |
| Load current (chip) | 3 A | TI LM2596 datasheet, p. 1 |
| Switching frequency | 150 kHz typical (127 kHz to 173 kHz at 25 °C) | TI LM2596 datasheet, pp. 1, 7 |
| Switch saturation voltage | 1.16 V typical, 1.4 V max at 3 A, 25 °C | TI LM2596 datasheet, p. 7 |
| Current limit | 4.5 A peak typical (3.6 A min at 25 °C) | TI LM2596 datasheet, p. 7 |
| Efficiency (TI test circuits, 3 A) | 73 % (3.3 V from 12 V), 80 % (5 V from 12 V), 90 % (12 V from 25 V) | TI LM2596 datasheet, p. 6 |
| Quiescent and standby current | 5 mA operating; 80 µA in standby (ON/OFF high) | TI LM2596 datasheet, p. 7 |
| Module terminals | IN+, IN-, OUT+, OUT- (IN- and OUT- common) | Tinkered component registry |
| Maximum supply voltage | 40 V | Tinkered component registry |
| Dimensions | 43 × 21 × 14 mm | Tinkered component registry |
| Weight | 12 g | Tinkered component registry |
| Output voltage | 1.2–37 V | maker's datasheet, checked 29 Oct 2026 |

## Circuit notes

- Set the output before connecting the load: power IN+ and IN-, put a multimeter on OUT+ and OUT-, and turn the trimmer until it reads the voltage you need. A module straight from the bag can be set to any voltage.
- Keep the input comfortably above the output. The chip's internal switch drops 1.16 V typical and up to 1.4 V at 3 A (TI datasheet, p. 7), plus the inductor's drop, so plan on at least 1.5 V of headroom: 6.5 V or more for a 5 V output.
- The input must be 4.5 V to 40 V (p. 5). A 2S or 3S lithium pack, a 9 V battery, or a 12 V or 24 V adapter all fit; never exceed 40 V, since the absolute maximum is 45 V.
- IN- and OUT- are the same ground on the module. Tie the microcontroller's GND to OUT- whenever the buck powers parts it talks to.
- Feed a development board through its regulated input (an Uno's VIN at 7 V to 12 V, or the 5 V input of a 5 V board) and never back into a 3.3 V output pin.
- The chip is rated for 3 A, but at high current the regulator and its diode heat up; TI's thermal considerations size the copper and heatsink for the power lost (pp. 5, 33). On a small module, add airflow or a heatsink for sustained loads near the limit.

## Common mistakes

- **Connecting the load before setting the voltage.** The trimmer can leave the output anywhere from about 1.2 V up to near the input. Set and measure OUT+ with a meter first, or the first power-up can overvolt a 5 V or 3.3 V part.
- **Too little input headroom.** A buck only steps down, and the LM2596's switch alone drops up to 1.4 V at 3 A (TI datasheet, p. 7). From a 6 V pack, a 5 V output sags under load; use a higher input or a lower output.
- **Swapping IN and OUT.** Power must go into IN+ and IN-. Feeding the supply into the OUT terminals does not regulate and can damage the chip and whatever is on the input side.
- **No common ground with the microcontroller.** A servo or LED strip powered by the buck needs its ground tied to the controller's GND, through OUT-, or its signal line has no reference.
- **Exceeding 40 V on the input.** The LM2596's operating input tops out at 40 V, with a 45 V absolute maximum (TI datasheet, p. 5). A 48 V supply or the spikes of a long motor cable can kill it; use a part rated higher.

## Questions

### How do I set the output voltage of an LM2596 module?

Power the input, put a multimeter across OUT+ and OUT-, and turn the brass multi-turn trimmer until the meter reads your target. On the chip the output is 1.23 V times (1 + R2/R1), with R1 about 1 kΩ (TI LM2596 datasheet, p. 28); the trimmer is R2.

### What input voltage does the LM2596 buck module accept?

4.5 V to 40 V on the chip's input, with a 45 V absolute maximum (TI LM2596 datasheet, p. 5). The input must also stay above the output by the switch's drop, up to 1.4 V at 3 A (p. 7).

### Can an LM2596 module power an Arduino, ESP32 or Raspberry Pi Pico?

Yes. Set it to 5 V and feed a 5 V input such as an ESP32 DevKit's VIN or a Pico's VSYS, or set it to 7 V to 12 V for an Uno's VIN. Never connect it to a board's 3.3 V output pin, and share ground.

### How much current can an LM2596 module supply?

The LM2596 chip is rated for a 3 A load, with a peak current limit of 4.5 A typical (TI LM2596 datasheet, pp. 1, 7). On a small module, heat in the chip, diode and inductor usually limits sustained current below that unless you add cooling.

### Why does my LM2596 output not change, or read the same as the input?

If the output follows the input, the input is too low for the setting: the switch runs at up to 100 % duty and simply passes the input minus its drop (TI LM2596 datasheet, p. 7). Lower the target or raise the input. If turning the trimmer does nothing, it is multi-turn: keep turning, it can take many turns to move.

### LM2596 buck vs AMS1117 or LM1117 linear regulator: which should I use?

A buck converter switches, reaching 73 % to 90 % efficiency at 3 A in TI's test circuits (LM2596 datasheet, p. 6). A linear regulator burns (VIN minus VOUT) times the current as heat. For 12 V to 5 V at more than a few hundred milliamps, use the buck; for a quiet 3.3 V from 5 V at low current, a linear regulator is simpler.

### LM2596 vs MT3608: what is the difference?

The LM2596 is a step-down (buck) converter: its output is always below its input (TI LM2596 datasheet, p. 1). An MT3608 module is a step-up (boost) converter that raises a voltage, for example from a single Li-ion cell to 5 V. Pick by whether you need less or more voltage than the supply gives.

## Related parts

- [9V Battery](https://www.tinkered.ai/components/battery-9v.md): wired with it in its circuit
- [SG90 Micro Servo](https://www.tinkered.ai/components/servo-sg90.md): wired with it in its circuit
- [MB102 Breadboard Power Module](https://www.tinkered.ai/components/mb102-power-module.md): same job: regulates a supply
- [AMS1117 3.3V Regulator Module](https://www.tinkered.ai/components/ams1117-3v3-module.md): same job: regulates a supply
- [LM1117 3.3V Regulator (TO-220)](https://www.tinkered.ai/components/lm1117t-3v3.md): same job: regulates a supply
- [MT3608 Boost Converter Module](https://www.tinkered.ai/components/mt3608-boost-module.md): same job: regulates a supply

## Try it

Tinkered can design a circuit with the LM2596 Buck Converter Module, draw its schematic and check it. Free to start at https://www.tinkered.ai.