How to Use NJM2670: Examples, Pinouts, and Specs

The NJM2670 is a low-dropout (LDO) voltage regulator designed to provide a stable output voltage with low noise and high power supply rejection. It is particularly well-suited for battery-powered devices, where efficiency and reliability are critical. The NJM2670 includes built-in features such as thermal shutdown and current limiting, ensuring safe operation under various conditions.

• Portable electronics and battery-powered devices
• Noise-sensitive analog circuits
• Microcontroller power supplies
• Audio equipment
• Wireless communication devices

• Input Voltage Range: 2.5V to 14V
• Output Voltage Range: 1.5V to 12V (fixed or adjustable, depending on the model)
• Output Current: Up to 1A
• Dropout Voltage: Typically 0.2V at 500mA
• Quiescent Current: Typically 50µA
• Thermal Shutdown: Yes
• Current Limiting: Yes
• Operating Temperature Range: -40°C to +85°C
• Package Options: TO-252, SOT-223, and others

The NJM2670 is available in multiple package types. Below is the pin configuration for the TO-252 package:

For the SOT-223 package, the pin configuration is as follows:

1. Input Capacitor: Connect a low-ESR capacitor (e.g., 10µF ceramic) between the VIN pin and ground to stabilize the input voltage.
2. Output Capacitor: Connect a low-ESR capacitor (e.g., 10µF ceramic) between the VOUT pin and ground to ensure stable operation and reduce output noise.
3. Thermal Considerations: Ensure proper heat dissipation by connecting the thermal pad (if available) to a large ground plane or using a heatsink.
4. Load Connection: Connect the load to the VOUT pin. Ensure the load current does not exceed the maximum rated output current (1A).
5. Power Supply: Provide an input voltage within the specified range (2.5V to 14V) to the VIN pin.

• Input Voltage: Ensure the input voltage is at least 0.2V higher than the desired output voltage to maintain proper regulation.
• Capacitor Selection: Use low-ESR capacitors for both input and output to minimize noise and improve stability.
• Thermal Management: Avoid overheating by ensuring adequate heat dissipation. Use a PCB layout with a large ground plane or thermal vias.
• Current Limiting: Do not exceed the maximum output current to prevent triggering the current limiting feature.

The NJM2670 can be used to power an Arduino UNO by providing a stable 5V output. Below is an example circuit and Arduino code:

1. Connect the VIN pin of the NJM2670 to a 9V battery.
2. Connect the GND pin to the ground of the circuit.
3. Connect the VOUT pin to the 5V pin of the Arduino UNO.
4. Add a 10µF capacitor between VIN and GND, and another 10µF capacitor between VOUT and GND.

// Example code for Arduino UNO powered by NJM2670
// This code blinks an LED connected to pin 13

void setup() {
  pinMode(13, OUTPUT); // Set pin 13 as an output
}

void loop() {
  digitalWrite(13, HIGH); // Turn the LED on
  delay(1000);            // Wait for 1 second
  digitalWrite(13, LOW);  // Turn the LED off
  delay(1000);            // Wait for 1 second
}

1. No Output Voltage

   • Cause: Input voltage is too low or not connected.
   • Solution: Verify that the input voltage is within the specified range (2.5V to 14V).

2. Excessive Heat

   • Cause: Overloading the regulator or insufficient heat dissipation.
   • Solution: Reduce the load current or improve thermal management by using a heatsink or larger ground plane.

3. Output Voltage Instability

   • Cause: Improper capacitor selection or insufficient capacitance.
   • Solution: Use low-ESR capacitors with the recommended values (e.g., 10µF ceramic).

4. Thermal Shutdown Triggered

   • Cause: Regulator temperature exceeds the safe operating limit.
   • Solution: Reduce the input voltage, decrease the load current, or improve heat dissipation.

Q1: Can the NJM2670 be used with a variable input voltage?
A1: Yes, as long as the input voltage remains within the specified range (2.5V to 14V) and is at least 0.2V higher than the desired output voltage.

Q2: What happens if the load current exceeds 1A?
A2: The NJM2670 includes a current limiting feature that will reduce the output current to protect the regulator from damage.

Q3: Can I use electrolytic capacitors instead of ceramic capacitors?
A3: While electrolytic capacitors can be used, low-ESR ceramic capacitors are recommended for better performance and stability.

Q4: Is the NJM2670 suitable for powering noise-sensitive circuits?
A4: Yes, the NJM2670 is designed for low noise and high power supply rejection, making it ideal for noise-sensitive applications.