LM21305 Datasheet | National Semiconductor

Description The LM21305 is a full featured adjustable frequency synchronous buck regulator capable of delivering up to 5A of continuous output current. The device is optimized to work over the input voltage range of 3V to 18V making it suitable for wide variety of applications. The LM21305 provides 1% output-voltage accuracy and excellent line and fast load transient response for digital loads. The device offers flexible system configuration via programmable switching frequency and ability to synchronize switching frequency. The device also provides internal soft-start to limit in-rush current, cycleby-cycle current limiting, and thermal shutdown. The device features internal over voltage protection (OVP) and over current protection (OCP) circuits for increased system reliability. A precision enable pin and integrated UVLO allows the turn-on of the device to be tightly controlled and sequenced. Start-up inrush currents are limited by an internal Soft-Start circuit. Fault detection and supply sequencing are possible with the integrated power good circuit. The frequency of this device can be adjusted from 300 k Hz to 1.5 MHz through an external resistor. The LM21305 is offered in a 28-pin LLP package. Key Specifications Features - Single rail input voltage from 3V to 18V - Feedback Voltage of 0.6V - 1% typical output voltage accuracy - High-efficiency switcher core - Switching frequency range: 300 k Hz to 1.5 MHz - Resistor programmable switching frequency - Ability to synchronize switching frequency - Precision enable - Internal soft-start to reduce in-rush current - PGOOD function - Under Voltage Lock Out (UVLO) - Over Voltage Protection (OVP) - Fast transient response - Cycle-by-cycle current limiting - Thermal shutdown - LLP-28 package (5mm x 5mm x 0.8mm, 0.5mm pitch) Applications - Point of Load regulation from 3.3V, 5V, and 12V rails - Power supply for DSPs, FPGAs, ASICs and Processors - Broadband, Networking and Optical munications Infrastructure Typical...