LM21305SQE/NOPB

Step-Down DC/DC Converters Integrated Switch 9V to 30V Input Max., Texas Instruments### 直流/直流开关调节器转换器（集成开关），Texas InstrumentsTexas Instruments 的此系列高度集成的高效开关稳压器包括步升（升压）、步降（降压）、步升/降（增压/降压）和反相类型，为每个直流稳压器应用提供高效的解决方案。

The LM21305 is a full-featured, 5-A, synchronous buck dc-dc converter optimized for solution size, flexibility, and high conversion efficiency. High-power density LM21305 designs are easily achieved by virtue of monolithic integration of high-side and low-side power MOSFETs, high switching frequency, peak current-mode control, and optimized thermal design. The efficiency of the LM21305 is maximized at light loads with diode emulation mode operation and at heavy loads by optimal design of the MOSFET adaptive gate drivers to minimize switch dead-times and body-diode conduction losses.

The LM21305 accepts a wide input voltage range of 3 V to 18 V for interface to various intermediate bus voltages, including 3.3-V, 5-V, and 12-V rails. A 1.5% voltage reference and 70-ns, high-side MOSFET minimum controllable on-time enable output voltages as low as 0.598 V with excellent setpoint accuracy. The LM21305 is available in a 5-mm × 5-mm2 WQFN-28 thermally-enhanced package with 0.5-mm pitch.

The LM21305 offers flexible system configuration with programmable switching frequency from 300 kHz to 1.5 MHz using one resistor or by external clock synchronization for beat-frequency-sensitive and multi-regulator applications. On-chip bias supply low-dropout LDO sub-regulators eliminate the need for an external bias power and simplify circuit board layout. The device also offers an internal soft-start to limit inrush current and provide monotonic startup capability into unbiased and pre-biased loads, integrated boot diodes, cycle-by-cycle current limiting, and thermal shutdown. Peak current-mode control with a high-gain error amplifier maintains stability throughout the entire input voltage and load current ranges, enabling excellent line and load transient response.

The LM21305 features internal output overvoltage protection OVP and overcurrent protection OCP circuits for increased system reliability. An integrated open-drain, PGOOD indicator provides output voltage monitoring, power-rail sequencing capability, and fault indication. Other features include thermal shutdown with automatic recovery, low PWM minimum on-time, low shutdown quiescent current, and precision enable with hysteresis for programmable line undervoltage lockout UVLO.