Overview
The LM21305SQ/NOPB is a high-performance, 5-A synchronous buck dc-dc converter designed by Texas Instruments. This device is optimized for solution size, flexibility, and high conversion efficiency, making it suitable for a wide range of power management applications. The LM21305 features monolithic integration of high-side and low-side power MOSFETs, peak current-mode control, and optimized thermal design, enabling high-power density designs.
Key Specifications
| Parameter | Value |
|---|---|
| Input Voltage Range | 3 V to 18 V |
| Output Current | Up to 5 A |
| Output Voltage Reference | 0.598 V ± 1.5% |
| Switching Frequency Range | 300 kHz to 1.5 MHz |
| Package Type | 28-Pin WQFN with Exposed Thermal Pad |
| Package Size | 5 mm × 5 mm |
| Minimum Controllable On-Time | 70 ns |
| Thermal Shutdown | With automatic recovery |
| Protection Features | Overvoltage Protection (OVP), Overcurrent Protection (OCP), Thermal Shutdown |
Key Features
- Programmable switching frequency from 300 kHz to 1.5 MHz using one resistor or external clock synchronization
- Internal output overvoltage protection (OVP) and overcurrent protection (OCP) circuits
- Integrated open-drain PGOOD indicator for output voltage monitoring, power-rail sequencing, and fault indication
- Thermal shutdown with automatic recovery
- Low PWM minimum on-time and low shutdown quiescent current
- Precision enable with hysteresis for programmable line undervoltage lockout (UVLO)
- Internal soft-start to limit inrush current and provide monotonic startup capability
- Integrated boot diodes and cycle-by-cycle current limiting
- On-chip bias supply low-dropout (LDO) sub-regulators
Applications
The LM21305 is versatile and can be used in various power management applications, including:
- Intermediate bus voltages such as 3.3 V, 5 V, and 12 V rails
- High-density power supply designs
- Multi-regulator systems where beat-frequency sensitivity is a concern
- Systems requiring high efficiency and reliability, such as in industrial, automotive, and consumer electronics
Q & A
- What is the input voltage range of the LM21305?
The input voltage range of the LM21305 is 3 V to 18 V. - What is the maximum output current of the LM21305?
The maximum output current of the LM21305 is up to 5 A. - What is the output voltage reference of the LM21305?
The output voltage reference of the LM21305 is 0.598 V ± 1.5%. - How can the switching frequency of the LM21305 be adjusted?
The switching frequency of the LM21305 can be adjusted from 300 kHz to 1.5 MHz using one resistor or by external clock synchronization. - What protection features does the LM21305 include?
The LM21305 includes overvoltage protection (OVP), overcurrent protection (OCP), and thermal shutdown with automatic recovery. - What is the package type and size of the LM21305?
The LM21305 is available in a 28-Pin WQFN package with an exposed thermal pad, measuring 5 mm × 5 mm. - Does the LM21305 have an internal soft-start feature?
Yes, the LM21305 has an internal soft-start feature to limit inrush current and provide monotonic startup capability. - What is the purpose of the PGOOD indicator in the LM21305?
The PGOOD indicator provides output voltage monitoring, power-rail sequencing capability, and fault indication. - Does the LM21305 support external frequency synchronization?
Yes, the LM21305 supports external frequency synchronization. - What are some common applications of the LM21305?
The LM21305 is commonly used in high-density power supply designs, multi-regulator systems, and applications requiring high efficiency and reliability.
