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LM22680MRE-ADJ/NOPB Step-Down Voltage Regulator Comprehensive Guide

Published Published: Jan 21, 2025     
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The LM22680MRE-ADJ/NOPB is an adjustable output, high-efficiency step-down (buck) regulator from Texas Instruments. It is designed for various power management applications where a precise and stable lower voltage is needed from a higher input voltage. Below is a comprehensive guide, including key specifications, features, application circuits, and more.

 

Key Features:

1. Wide Input Voltage Range:  

   - 4.5V to 60V (supports wide input range, including 24V, 12V, and 5V input systems).

 

2. Adjustable Output Voltage:

   - 0.8V to 15V adjustable output voltage range using an external resistor divider.

 

3. High Efficiency:

   - Can achieve efficiencies up to 95%, depending on input and output voltage.

 

4. Output Current:

   - Can deliver up to 5A continuous output current with appropriate heat dissipation.

 

5. Low Quiescent Current:

   - Quiescent current of only 30µA, ensuring minimal power loss in no-load or light-load conditions.

 

6. Switching Frequency:

   - Fixed 500kHz or adjustable (depending on design).

   

7. Overvoltage and Undervoltage Lockout:  

   - Built-in OV/UV lockout to protect against unstable operating conditions.

 

8. Integrated Protection Features:

   - Overcurrent protection (OCP), overvoltage protection (OVP), and thermal shutdown (TSD).

   

9. Low Ripple:

   - Low ripple and noise due to internal filtering.

 

10. High Switching Frequency:

    - Typically 500kHz for fast response time.

 

11. Soft-Start:  

    - Soft-start circuitry for reduced inrush current during startup.

 

12. Thermal Shutdown and Hiccup Mode:

    - Integrated thermal protection and a hiccup mode to prevent damage from excessive heat or overcurrent events.

 

13. External Compensation:  

    - External feedback compensation for optimizing stability and transient response.

Applications:

· Industrial Power Supplies: For powering field devices and control circuits with tight voltage regulation requirements.

· Automotive Power Systems: Converts high-voltage automotive battery to lower voltage for system control, infotainment, or sensor systems.

· Telecom Power: Used for providing low-voltage rails in telecom and base station applications.

· Battery-Powered Systems: Efficient conversion of battery voltage to lower levels for systems like portable devices, remote sensors, and medical devices.

· Power Management in Embedded Systems: Efficient DC-DC regulation in embedded systems with tight power and voltage constraints.

 

Pinout (16-pin package):

The LM22680MRE-ADJ/NOPB comes in a 16-pin TSSOP package. The following is the general pinout:

1. VIN (Pin 1): Input voltage pin (4.5V to 60V)

2. SW (Pin 2): Switching node (connected to the inductor and external power MOSFET).

3. PGND (Pin 3): Power ground (used to connect the ground of the power side of the regulator).

4. FB (Pin 4): Feedback input, used to set the output voltage by connecting a resistor divider.

5. COMP (Pin 5): Compensation pin (for external feedback compensation).

6. VOUT (Pin 6): Output voltage pin.

7. EN (Pin 7): Enable pin (high to enable, low to disable).

8. FREQ (Pin 8): Frequency adjust pin (for adjusting the switching frequency in the external configuration).

9. REF (Pin 9): Internal voltage reference, typically used for setting the feedback voltage.

10. SS (Pin 10): Soft-start pin for controlling the rise time of the output voltage.

11. PGOOD (Pin 11): Power good status output, indicating that the output voltage is within regulation limits.

12. GND (Pin 12): Ground pin for control and signal section.

13. PGND (Pin 13): Power ground pin (for the high-current section).

14. LX (Pin 14): Output inductor node.

15. VOUT (Pin 15): Main output voltage pin.

16. VSS (Pin 16): Auxiliary ground pin (typically used for low-power control).

Functional Block Diagram:

The LM22680 consists of several key functional blocks:

· High Efficiency PWM Controller: Includes the core of the step-down regulator that drives the internal power switch.

· Feedback Circuitry: Uses external resistors to set the output voltage based on the reference voltage.

· Protection Circuitry: Includes overvoltage, undervoltage, overcurrent, and thermal protection mechanisms.

· MOSFET Driver: Drives an external MOSFET (if used), ensuring high efficiency.

 

Detailed Electrical Specifications:

· Input Voltage (V_in): 4.5V to 60V

· Output Voltage (V_out): 0.8V to 15V (adjustable via external resistors)

· Maximum Output Current: 5A (depending on thermal performance and ambient conditions)

· Efficiency: Up to 95% (typical)

· Operating Frequency: 500kHz (fixed) or adjustable (via external resistor/capacitor for custom applications)

· Output Ripple: Low (depending on external capacitors and inductors)

· Quiescent Current (I_Q): 30µA (typical)

· Soft Start Time: 4ms (typical)

 

Typical Application Circuit:

In a basic Buck Converter application, the LM22680MRE-ADJ/NOPB typically uses:

· Inductor (L): 10µH to 100µH inductor to filter the switching ripple and maintain steady output voltage.

· Input Capacitor (C_in): Typically 10µF to 100µF ceramic capacitor for input filtering.

· Output Capacitor (C_out): 47µF to 330µF ceramic or electrolytic capacitor for output smoothing.

· Resistor Divider (R1, R2): Determines the output voltage by selecting appropriate resistor values.

Example:

For a 5V output, a typical resistor divider might have:

· R1 = 100kΩ

· R2 = 33kΩ

 

Thermal Performance:

· Thermal Shutdown: Integrated thermal protection with automatic recovery (hiccup mode).

· Thermal Resistance: Junction to ambient thermal resistance typically around 50°C/W (depends on board design).

 

Protection Features:

· Overcurrent Protection: Limits output current to prevent damage to the device.

· Undervoltage Lockout (UVLO): Prevents operation when the input voltage is too low to maintain stable operation.

· Overvoltage Protection (OVP): Ensures that the output voltage does not exceed safe operating limits.

· Overtemperature Protection (OTP): Limits temperature to prevent thermal damage.

 

Applications:

· Industrial Power Supply: Powers equipment requiring a 5V, 12V, or 15V output from a higher voltage source.

· Automotive Power Systems: Converts high 12V or 24V automotive battery voltage to regulated lower voltage rails.

· Battery-Powered Systems: Powers low-voltage devices from a battery with high efficiency.

· Communication Equipment: Powering communication equipment requiring tightly regulated voltage rails.

 

Recommended Compatible Component Series

 

To fully utilize the LM22680MRE-ADJ/NOPB in various applications, consider the following compatible electronic components:

 

1. TI's TPS62150 Series - Synchronous Step-Down Converters

· Category: DC-DC converters

· Parameters: Input Voltage: 4.75V to 28V, Output Current: up to 1A

· Application Scenarios: Suitable for systems requiring additional low-noise, high-efficiency power conversion stages.

· Specific Models: TPS62150-Q1, designed for automotive and industrial environments.

 

2. Coilcraft XAL6060 Series - High-Current Inductors

· Category: Power Inductors

· Parameters: Inductance Range: 0.27 µH to 10 µH, Saturation Current: up to 24.2A

· Application Scenarios: Ideal for use with LM22680 in high-output current designs, providing stable operation and low ripple.

· Specific Models: XAL6060-103ME, offering 10 µH and rated for automotive environments.

 

3. Panasonic SEPF Series - Polymer Electrolytic Capacitors

· Category: Output Capacitors

· Parameters: Capacitance: 100 µF to 470 µF, Voltage Rating: up to 16V, Low ESR.

· Application Scenarios: Essential for maintaining low ripple in high-frequency applications where stable voltage output is critical.

· Specific Models: SEPF470M160ST, with low ESR and excellent performance in high-temperature environments.

 

4. Murata GRM31CR61C476KE15L - Multilayer Ceramic Capacitors

· Category: Input Capacitors

· Parameters: Capacitance: 47 µF, Voltage Rating: 16V, Temperature Coefficient: X5R

· Application Scenarios: Suitable as an input capacitor for high-frequency switching regulators.

· Specific Models: GRM31CR61C476KE15L, a compact capacitor for stabilizing input voltage.

 

5. Diodes Inc. B120/B140 Series - Schottky Barrier Rectifiers

· Category: Power Diodes

· Parameters: Voltage: up to 40V, Average Forward Current: 1A

· Application Scenarios: Effective for applications needing fast recovery and low forward voltage.

· Specific Models: B140-13-F, ideal for output rectification due to its low forward voltage drop and fast switching characteristics.

 

 

 

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