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 monitors

■ Networking: XDSL, modems, DC-DC modules

■ Computer: printers, audio/graphic cards, optical storage, hard disk drive

■ Industrial: changers, car battery, DC-DC converters


图1.L5973D测试应用电路

图2.L5973D演示板应用电路

演示板应用电路元件列表:



图3.L5973D正向升压/降压稳压器

图4.L5973D升压/降压稳压器

图5.L5973D带辅助绕组的双输出电压稳压器

STEVAL-ILL007V1: High intensity LED driver for MR-16 format based on L5973D
This reference design is a constant current driver for high brightness LEDs. The supply input voltage can be either 12 V AC or DC, and for DC it can range from 6 V to 24 V. It can also be adapted for reverse battery protection in automotive applications. The output is a constant current that can drive a single or multiple LEDs in series at 350 mA, 700 mA or 1.05 A.

STEVAL-ILL007V1 HBLED驱动器特性:

■ This evaluation board was designed so that it can be configured to accept several different input voltages

■ The most common input voltages are 12 Vac, 12 Vdc (for automotive) and 24 Vdc

■ The board also allows the user to select the output current by using jumpers setting only

■ The standard configuration of the board includes a full wave bridge rectifier that is
required for an AC input


图6.STEVAL-ILL007V1 HBLED驱动器外形图

图7.STEVAL-ILL007V1 HBLED驱动器电路图