- The heart of the high efficiency switch with integrated low RDSONPower MOSFETs
- Programmable switching frequency where resistors are synchronized to frequency
- Internal soft-start with monotonic and prebiased start-up
- Low quiescent current shutdown
- Precision enable hysteresis
- PGOOD indicates the function
- Input Undervoltage Lockout (UVLO)
- Output Overvoltage Protection (OVP)
- High bandwidth load transient response with peak current mode control
- Cycle-by-cycle current limit
- Thermal shutdown
illustrate
The LM21305 is a full-featured 5A synchronous buck regulator optimized for solution size, flexibilty, and high conversion efficiency. The high power density LM21305 is designed to optimize the integration of thermal designs with high-side and low-side power MOSFETs, high switching frequency, and current-mode control. The LM21305 improves efficiency with diode emulation mode in light load operation and heavy loads optimized by MOSFET gate drivers to minimize switching dead time and body diode on-turn-on losses.
The LM21305 implements a wide input voltage range of 3V to 18V, facilitating an interface to all intermediate bus voltages, including 3.3V, 5V and 12V power rails. An output voltage setpoint as low as 0.6V is supported with excellent accuracy and low ripple and RMS noise. The LM21305 offers programmable switching frequencies from 300 kHz to 1.5 MHz using a single resistor or synchronizing flexible system configurations via an external clock. On-chip bias power supply sub-supervision reduces the need for external bias supplies and simplifies PCB layout. The device also features internal soft-start to limit inrush current, prebias start-up and monotony, cycle-by-cycle current limit, and thermal shutdown. Peak current mode, high gain error amplifier control maintains stability over the entire input voltage and load current range, enabling superior voltage and load transient response.
Available in an LLP-28 package with enhanced thermal dissipation, the LM21305 features internal output overvoltage and overcurrent protection circuitry for improved system reliability. A high-precision enable pin and integrated input UVLO allow for tight control and sequencing device turn-on. The comprehensive open-drain power good indicator provides rail sequencing capability and fault indication.
Main specifications
- The single-rail input voltage range is 3V to 18V
- 0.6V feedback voltage reference
- Switching frequency range from 300 kHz to 1.5 MHz
- LLP - 28 package (5 × 5 × 0.8 mm, 0.5 mm pitch)
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- POL regulates from 3.3V, 5V, and 12V rails
- High efficiency power supplies to DSPs, FPGAs, ASICs and processors
- Broadband, optical communication networks and infrastructure
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