How to Use MIC2571: Examples, Pinouts, and Specs

The MIC2571 is a high-efficiency, step-up (boost) DC-DC converter designed to provide a regulated output voltage from a lower input voltage. It integrates a built-in switch and operates with low quiescent current, making it ideal for battery-powered applications. The MIC2571 is commonly used in portable devices, handheld electronics, and other applications requiring efficient voltage boosting.

• Portable electronics (e.g., cameras, MP3 players)
• Battery-powered devices
• LCD bias supplies
• LED drivers
• Wireless communication devices

• Input Voltage Range: 2.0V to 16.5V
• Output Voltage Range: Adjustable up to 34V
• Switch Current Limit: 1.5A (typical)
• Quiescent Current: 120µA (typical)
• Efficiency: Up to 90% (depending on load and configuration)
• Operating Frequency: 120kHz (fixed)
• Package Options: 8-pin DIP or SOIC

The MIC2571 is available in an 8-pin package. Below is the pinout and description:

1. Input and Output Capacitors:

   • Place a low-ESR capacitor (e.g., 10µF ceramic) close to the VIN pin to stabilize the input voltage.
   • Use an appropriate output capacitor (e.g., 22µF ceramic or electrolytic) to smooth the output voltage.

2. Inductor Selection:

   • Choose an inductor with a current rating higher than the MIC2571's switch current limit (1.5A).
   • Typical inductance values range from 10µH to 47µH, depending on the desired output voltage and current.

3. Feedback Resistor Divider:

   • Use two resistors to set the output voltage. The formula is: [ V_{OUT} = V_{REF} \times \left(1 + \frac{R1}{R2}\right) ] where ( V_{REF} = 1.25V ).

4. Compensation Capacitor:

   • Connect a capacitor (e.g., 1nF to 10nF) to the COMP pin for loop stability.

5. Shutdown Control:

   • To enable the MIC2571, pull the SHDN pin high (e.g., connect to VIN).
   • To disable the MIC2571, pull the SHDN pin low (e.g., connect to GND).

Below is a basic circuit diagram for a 5V output from a 3.3V input:

• Input Voltage (VIN): 3.3V
• Output Voltage (VOUT): 5V
• Inductor: 22µH
• Feedback Resistors: R1 = 10kΩ, R2 = 5.6kΩ
• Input Capacitor: 10µF
• Output Capacitor: 22µF

The MIC2571 can be used with an Arduino UNO to power external components requiring a higher voltage. Below is an example code to control the MIC2571's shutdown pin:

// MIC2571 Shutdown Control Example
// This code toggles the SHDN pin of the MIC2571 using Arduino UNO's digital pin 7.

#define SHDN_PIN 7  // Define the Arduino pin connected to the MIC2571 SHDN pin

void setup() {
  pinMode(SHDN_PIN, OUTPUT);  // Set SHDN_PIN as an output
  digitalWrite(SHDN_PIN, HIGH);  // Enable the MIC2571 (pull SHDN high)
}

void loop() {
  // Toggle the MIC2571 on and off every 5 seconds
  digitalWrite(SHDN_PIN, LOW);  // Disable the MIC2571 (pull SHDN low)
  delay(5000);  // Wait for 5 seconds
  digitalWrite(SHDN_PIN, HIGH);  // Enable the MIC2571 (pull SHDN high)
  delay(5000);  // Wait for 5 seconds
}

• Ensure the input voltage is within the specified range (2.0V to 16.5V).
• Select components (inductor, capacitors, and resistors) based on the desired output voltage and current.
• Keep traces for the SW pin and associated components (inductor, diode) as short as possible to minimize noise.
• Use proper heat dissipation techniques if operating at high currents.

1. Can the MIC2571 be used for negative voltage outputs?

   • No, the MIC2571 is designed for positive voltage step-up applications only.

2. What is the maximum output current the MIC2571 can provide?

   • The maximum output current depends on the input voltage, output voltage, and inductor selection. Refer to the datasheet for detailed calculations.

3. Can I leave the SHDN pin floating?

   • No, the SHDN pin must be pulled high to enable the device or pulled low to disable it. Leaving it floating may cause unpredictable behavior.

4. What type of diode should I use with the MIC2571?

   • Use a fast-recovery Schottky diode with a current rating higher than the output current.

By following this documentation, users can effectively integrate the MIC2571 into their designs for efficient voltage boosting.