MP1584

MP1584 / MP1584EN
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Function	Step-Down DC-DC Converter (Buck Converter)
Type	Integrated Circuit / Breakout Module
Manufacturer	Monolithic Power Systems (MPS)
Operating Voltage	Input: 4.5V – 28V / Output: 0.8V – 20V (adjustable)
Current Rating	3A maximum output
Package	SOIC-8 (IC) / Breakout Module
Interface	Analog (potentiometer adjustment)
Typical Cost	$0.50 – $1.50 USD (module)
Datasheet	MP1584 Datasheet (MPS)

The MP1584 (or MP1584EN) is a high-efficiency step-down (buck) DC-DC converter IC commonly used to provide regulated voltage for microcontrollers and other electronics. It's widely available as a small breakout module with an adjustable output voltage.

Overview

The MP1584 is a switching regulator that efficiently converts a higher input voltage to a lower output voltage. Unlike linear regulators, which waste excess voltage as heat, buck converters use high-frequency switching and energy storage (inductors and capacitors) to achieve >90% efficiency.

For robotics applications, the MP1584 module is typically used to step down battery voltage (6V from 4× AA batteries) to the 3.3V or 5V required by microcontrollers and sensors.

Key Features

• High Efficiency: Up to 96% efficiency (typical 92% at moderate loads)
• Wide Input Range: 4.5V to 28V input
• Adjustable Output: 0.8V to 20V (must be lower than input)
• High Current: 3A maximum output current
• Compact Size: Module typically 22mm × 17mm × 4mm
• Over-Current Protection: Built-in current limiting
• Thermal Shutdown: Protects IC from overheating
• Fixed Switching Frequency: 1.5 MHz (reduces inductor/capacitor size)

Module Configuration

The typical MP1584 breakout module includes:

• MP1584EN IC: The switching regulator chip
• Inductor: Energy storage element (typically 22µH or 33µH)
• Input Capacitor: Smooths input voltage
• Output Capacitor: Smooths output voltage
• Potentiometer: Adjusts output voltage
• Input/Output Terminals: Screw terminals or solder pads

Pin Configuration

Typical module pinout:

• IN+ / VIN: Positive input voltage (4.5V – 28V)
• IN− / GND: Ground input
• OUT+ / VOUT: Positive output voltage (adjustable)
• OUT− / GND: Ground output

How Buck Converters Work

A buck converter uses:

1. Switching Transistor: Rapidly switches input voltage on/off (1.5 MHz in MP1584)
2. Inductor: Stores energy when switch is ON, releases when OFF
3. Diode (or synchronous rectifier): Provides current path when switch is OFF
4. Capacitor: Smooths the output voltage

The output voltage is controlled by the duty cycle (percentage of time the switch is ON):

$V_{out}=V_{in}\times D$

Where D is the duty cycle (0 to 1). The MP1584's feedback loop automatically adjusts the duty cycle to maintain the set output voltage.

Adjustment Procedure

CRITICAL: Always adjust the buck converter BEFORE connecting it to your circuit!

1. Do NOT connect your microcontroller or other electronics yet
2. Connect a voltmeter to the output terminals
3. Apply power to the input (e.g., connect battery)
4. Use a small screwdriver to adjust the potentiometer
5. Turn clockwise to increase voltage, counter-clockwise to decrease
6. Set to desired voltage (e.g., 3.3V for Raspberry Pi Pico)
7. Verify voltage is stable
8. Disconnect power
9. Now you can connect the buck converter to your circuit

WARNING: If you connect electronics before adjusting, the output could be too high and damage your components. Always set the voltage first!

Usage in BRS Projects

The MP1584 is used in SimpleBot's BRS Differential Drive Robot Control Board to convert the 6V battery voltage (4× AA batteries) down to 3.3V for the Raspberry Pi Pico.

Why Use a Buck Converter?

• Efficiency: ~92% efficient vs. ~60% for linear regulators at this voltage drop
• Less Heat: Wasted energy is minimized, so the converter stays cool
• Battery Life: Higher efficiency means longer runtime on the same batteries
• Stable Voltage: Output remains constant even as battery voltage drops

Design Considerations

• Input Voltage Range: 4× fresh AA batteries = 6V, but drops to ~4.8V when depleted. The MP1584's 4.5V minimum input means the robot will function until batteries are nearly dead.
• Output Current: The Pico and sensors draw <500mA, well within the 3A capability
• Capacitors: The module's capacitors smooth out voltage ripple for clean microcontroller power

Efficiency Comparison

For 6V → 3.3V conversion at 500mA load:

Regulator Type	Efficiency	Power Loss	Heat
MP1584 (Buck)	~92%	0.14W	Minimal
LM1117 (Linear)	~55%	1.35W	Significant
AMS1117 (Linear)	~55%	1.35W	Significant

The buck converter wastes 90% less power as heat!

Heat Dissipation

At moderate loads (<1.5A), the MP1584 module requires no heatsink. At higher currents, the IC and inductor will warm up:

• <1A: No heatsinking needed
• 1-2A: Module may become warm (safe)
• 2-3A: Module will become hot; ensure good airflow or add heatsink

Common Issues

• Output Voltage Too High: Adjust potentiometer before connecting load
• Output Voltage Drops Under Load: Input voltage too low or module current limit reached
• Excessive Ripple: Bad capacitors or counterfeit module
• Module Gets Hot: Normal at high currents, but check for short circuits
• No Output: Input voltage below 4.5V or module damaged

Alternatives

• LM2596: Older buck converter, lower frequency (52 kHz), lower efficiency, but very common
• XL4015: Higher current capability (5A) for more powerful applications
• MP2307: Smaller package, lower current (3A max)
• Linear Regulators (LM1117, AMS1117): Simpler but much less efficient

Buck vs. Linear Regulator

Feature	Buck Converter (MP1584)	Linear Regulator (LM1117)
Efficiency	85-96%	50-70%
Heat Generation	Low	High
Output Ripple	Some (mV)	Very low
Component Count	More (L, C, diode)	Fewer (just capacitors)
Cost	$1-1.50	$0.30-0.50
Complexity	Higher	Lower
Best For	Battery power	Clean, low-current supplies

For battery-powered robots, buck converters are almost always the better choice.

See Also

• BRS Differential Drive Robot Control Board - Uses MP1584 for power regulation
• SimpleBot - Powered by 4× AA batteries via MP1584
• Buck_converter - More on step-down converters
• Linear_regulator - Alternative voltage regulation method