ST L5973D MR-16格式HBLED驱动方案

ST 公司的L5973D是降压单片开关功率稳压器,开关电流大于2.5A,可向负载提供2A直流电流,输入电压从4V到36V,输出电压可设定为1.235V到35V,基准电压3.3 V / (±2%),LDO工作,100%占空比,内部固定频率250kHz,零负载电流工作和热关断特性,主要用在消费类电子如STB, DVD,TV, VCR,汽车收音机,LCD监视器,网络设备如常XDSL,调制解调器,DC/DC模块,计算机如打印机,音频/图像卡,光存储,硬盘驱动,以及工业如汽车电池,EC/EC转换器等.本文介绍了L5973D主要特性, 测试应用电路, 演示板电路和所用元件列表以及多种典型应用与MR-16格式HBLED驱动器的特性和详细电路图.
The L5973D is a step down monolithic power switching regulator with a minimum switch current limit of 2.5 A so it is able to deliver more than 2 A DC current to the load depending on the application conditions.
The output voltage can be set from 1.235 V to 35 V. The high current level is also achieved thanks to an SO8 package with exposed frame, that allows to reduce the Rth(j-amb) down to approximately 40℃/W.
The device uses an internal P-channel D-MOS transistor (with a typical Rdson of 250 mΩ) as switching element to minimize the size of the external components.
An internal oscillator fixes the switching frequency at 250 kHz. Having a minimum input voltage of 4 V only, it is particularly suitable for 5 V bus, available in all computer related applications.
Pulse by pulse current limit with the internal frequency modulation offers an effective constant current short circuit protection.
L5973D主要特性:
■ 2.5 A internal switch
■ Operating input voltage from 4 V to 36 V
■ 3.3 V / (±2%) reference voltage
■ Output voltage adjustable from 1.235 V to 35 V
■ Low dropout operation: 100 % duty cycle
■ 250 kHz internally fixed frequency
■ Voltage feedforward
■ Zero load current operation
■ Internal current limiting
■ Inhibit for zero current consumption
■ Synchronization
■ Protection against feedback disconnection
■ Thermal shutdown
L5973D应用:
■ Consumer: STB, DVD, TV, VCR, car radio, LCD mon...