ADI ADP2102/1653 LED驱动方案

2009-07-15 15:57:00 ADI, , ,

ADP2102低静态电流降压式DC/DC变换器和ADP1653 白色LED闪光灯驱动器都属于电源管理集成电路(IC)，它们适合于便携式手持应用，例如无线手机、数码照相机和其它应用。这两款芯片以高达95%的电源效率显著延长了电池寿命，并且配合节能模式在轻负载条件下降低了开关频率。此外，它们还提供过压和欠压锁定以及软启动功能，有助于减少或消除启动期间电池过度放电或启动电流过冲造成的损害影响。当射频（RF）发射期间放大器的电流突然增加时，ADP1653提供一种独特的功能——当在RF传输时，Tx masking启动，降低闪光灯LED的消耗电流。这两款芯片在小尺寸封装中实现了这些附加的性能。本文介绍了ADP2102和ADP1653的主要性能，应用电路以及ADP1653闪光LED驱动器评估板中主板和子板的详细电路图。

1．
The ADP2102 is a synchronous step-down dc-to-dc converter that converts a 2.7 V to 5.5 V unregulated input voltage to a lower regulated output voltage with up to 95% efficiency and 1% accuracy. The low duty cycle capability of the ADP2102 is ideal for USB applications or 5 V systems that power up submicron subvolt processor cores. Its 3 MHz typical operating frequency and excel-lent transient response allow the use of small, low cost 1 μH inductors and 2.2 μF ceramic capacitors. At medium-to-high load currents, it uses a current mode, pseudofixed frequency pulse-width modulation to extend battery life. To ensure the longest battery life in portable applications, the ADP2102 has a power save mode (PSM) that reduces the switching frequency under light load conditions to significantly reduce quiescent current.
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