- At the heart of the high-efficiency switch, a low-R DSON power MOSFET is integrated
- Resistor synchronized with frequency programmable switching frequency
- Internal soft start with monotonic and pre-bias start
- Low quiescent current shutdown
- Precision activation lag
- PTOO indication function
- Input Undervoltage Lockout (UVLO)
- Output Overvoltage Protection (OVP)
- High-bandwidth load transient response and peak current mode control
- Cycle-by-cycle current limit
- Thermal shutdown
illustrate
The LM21305 is a full-featured 5A synchronous buck regulator solution with optimized size, flexibility, high conversion efficiency. High power density LM21305 design enables monolithic integration through high-side and low-side power MOSFETs, high switching frequency, current mode control, and optimized thermal design. The LM21305 efficiency enhancement with diode simulation mode minimizes switching dead time and body diode conduction losses in light load operation and heavy loads optimized by MOSFET gate drivers.
The LM21305 implements a wide input voltage range of 3V to 18V, facilitating interfaces, 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 resistor or synchronization with an external clock for flexible system configurations. On-chip bias power supply sub-supervision reduces the need for external bias power supplies and simplifies PCB layout. The device also features an internal soft-start limit inrush current, a pre-bias start function, monotony, cycle-by-cycle current limiting, 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, LM21305 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 opening. The integrated open-drain power good indicator provides rail sequencing capability and fault indication.
Key specifications:
- The monorail 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 regulation from 3.3V, 5V and 12V power rails
- High-efficiency power supplies for DSPs, FPGAs, ASICs, and processors
- broadband, optical communication networks and infrastructure
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