Datasheet > LM21305

LM21305

更新时间： 2024-11-23 11:33:59

品牌	Logo	应用领域
美国国家半导体 - NSC		稳压器
页数	文件大小	规格书
24页	1429K
描述
5A Adjustable Frequency Synchronous Buck Regulator

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LM21305 数据手册

September 27, 2011

LM21305

5A Adjustable Frequency Synchronous Buck Regulator

General Description

Key Specifications

The LM21305 is a full-featured 5A synchronous buck POL

regulator optimized for solution size, flexibilty, and high con-

version efficiency. High power density LM21305 designs are

achieved via monolithic integration of the high-side and low-

side power MOSFETs, high switching frequency, current-

mode control, and optimized thermal design. The efficiency

of the LM21305 is elevated at light loads with diode emulation

mode operation and at heavy loads by optimal design of the

MOSFET gate drivers to minimize switch dead-times and

body-diode conduction losses.

Single-rail input voltage range from 3V to 18V

■

0.598V feedback voltage reference

300 kHz to 1.5 MHz switching frequency range

LLP-28 package (5 x 5 x 0.8 mm, 0.5 mm pitch)

Features

High efficiency switcher core with integrated low R_DSon

power MOSFETs

■

Resistor programmable switching frequency with

frequency synchronization

■

The LM21305 accepts a wide input voltage range of 3V to

18V, facilitating interface to all intermediate bus voltages, in-

cluding 3.3V, 5V and 12V rails. An output voltage as low as

0.598V is supported with excellent setpoint accuracy and low

ripple and RMS noise. The LM21305 offers flexible system

configuration with programmable switching frequency from

300 kHz to 1.5 MHz using one resistor or via external clock

synchronization. On-chip bias supply sub-regulators alleviate

the need for external bias power and simplify PCB layout. The

device also offers internal soft-start to limit inrush current, pre-

biased and monotonic startup capability, cycle-by-cycle cur-

rent 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

and enables excellent line and load transient response.

Internal soft-start with monotonic and pre-biased startup

■

Low shutdown quiescent current

Precision enable with hysteresis

PGOOD indicator function

Input under-voltage lock-out (UVLO)

Output over-voltage protection (OVP)

High-bandwidth load transient response with peak

current-mode control

Cycle-by-cycle current limiting

■

Thermal shutdown

Applications

Offered in a thermally enhanced LLP-28 package, the

LM21305 features internal output over-voltage and over-cur-

rent protection circuits for increased system reliability. A pre-

cision enable pin and integrated input UVLO allow the turn-

on of the device to be tightly controlled and sequenced. An

integrated open-drain power good indicator provides power

rail sequencing capability and fault indication.

POL regulation from 3.3V, 5V, and 12V supply rails

■

High efficiency supply for DSPs, FPGAs, ASICs and

processors

Broadband, networking and optical communications

infrastructure

■

Typical Application Circuit

30111101

301111

www.national.com

12 3 4 5 6 7...24

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与LM21305相关器件

型号	品牌	获取价格	描述	数据表
LM21305_11	NSC	获取价格	5A Adjustable Frequency Synchronous Buck Regulator
LM21305_15	TI	获取价格	5A Adjustable Frequency Synchronous Buck Regulator
LM21305SQ	NSC	获取价格	5A Adjustable Frequency Synchronous Buck Regulator
LM21305SQ/NOPB	TI	获取价格	5A Adjustable Frequency Synchronous Buck Regulator
LM21305SQE	NSC	获取价格	5A Adjustable Frequency Synchronous Buck Regulator
LM21305SQE/NOPB	TI	获取价格	5A Adjustable Frequency Synchronous Buck Regulator
LM21305SQX	NSC	获取价格	5A Adjustable Frequency Synchronous Buck Regulator
LM21305SQX/NOPB	TI	获取价格	5A Adjustable Frequency Synchronous Buck Regulator
LM213-155.52M	CONNOR-WINFIELD	获取价格	5.0x7.0mm Surface Mount LVDS Clock Oscillator Series
LM216	NSC	获取价格	OPERATIONAL AMPLIFIERS

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