How to Use MRB045: Examples, Pinouts, and Specs

The MRB045 is a fixed-value resistor with a resistance of 45 ohms. Resistors are passive electronic components that are fundamental to most electronic circuits. They are used to control the flow of current, divide voltages, and can be used in a variety of applications such as in voltage regulation, timing circuits, and as pull-up/pull-down resistors on digital inputs or outputs.

• Limiting current to LEDs and other sensitive components
• Pull-up/pull-down resistors for microcontroller inputs
• Voltage divider networks
• Analog circuits
• Timing circuits with capacitors (RC circuits)

• Resistance: 45 ohms
• Tolerance: ±5% (common for carbon film resistors)
• Power Rating: 0.25W (1/4 Watt) typical, but verify based on part number
• Maximum Operating Voltage: V_max = sqrt(Power Rating * Resistance)
• Temperature Coefficient: Varies with material, often around -55°C to 155°C for carbon film

Since a resistor is a two-terminal component, the MRB045 does not have a complex pin configuration. The two terminals are identical and interchangeable, known as non-polarized. The resistor can be connected in any direction in a circuit.

1. Current Limiting: To limit the current to a component like an LED, connect the MRB045 in series with the component.

2. Voltage Divider: To create a voltage divider, connect two resistors in series across a voltage source. The MRB045 can be one of these resistors.

3. Pull-Up/Pull-Down: Connect the MRB045 between a digital input pin and VCC for a pull-up or between the pin and GND for a pull-down.

• Ensure the power rating is not exceeded to prevent damage.
• Consider the tolerance when designing precision circuits.
• Be mindful of the temperature coefficient in temperature-sensitive applications.

// Define the pin where the LED is connected
const int ledPin = 13;

void setup() {
  // Set the LED pin as an output
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // Turn on the LED with a 45-ohm resistor in series
  digitalWrite(ledPin, HIGH);
  delay(1000); // Wait for 1 second
  // Turn off the LED
  digitalWrite(ledPin, LOW);
  delay(1000); // Wait for 1 second
}

Note: The MRB045 resistor should be connected in series with the LED to limit the current. The exact connection point can be either at the anode or cathode side of the LED.

• Excessive Heat: If the resistor is too hot, it may be dissipating more power than its rating allows. Check the current through the resistor and the voltage across it.
• No Effect in Circuit: If the resistor seems to have no effect, ensure it is properly connected and not bypassed by another conductive path.

• Verify Connections: Ensure that the resistor is properly soldered or connected to the circuit.
• Check Power Rating: Use Ohm's law (V=IR) and the power equation (P=IV) to ensure the power rating is not exceeded.
• Measure Resistance: Use a multimeter to confirm the resistance value is as expected.

Q: Can I use the MRB045 in a high-power application? A: No, the MRB045 is typically rated for 0.25W. For high-power applications, use a resistor with an appropriate power rating.

Q: Does the orientation of the resistor matter in a circuit? A: No, resistors are non-polarized components and can be connected in any direction.

Q: What happens if I use a resistor with a tolerance higher than 5%? A: The actual resistance value may vary more from the specified 45 ohms, which can be critical in precision circuits.

Q: Can I connect multiple MRB045 resistors in parallel or series for different applications? A: Yes, connecting in series increases the total resistance, while parallel connections decrease it. This can be used to achieve specific resistance values or power ratings.