Dual Boost Regulator Handles H
among 2-cell boost regulators, five watts (5v at 1a) is high power. but, obtaining even 5w from a 2-cell or 3-cell battery is not a trivial problem. peak currents exceed 2a, and the small voltage drops they produce in the power devices, battery, capacitors, and pc wiring can lead to poor efficiency and failure. the high internal impedance of alkaline aa batteries, for example, can support 5w loads only for short surges.
combining the outputs of two simple boost regulators with a diode-or connection (figure 1) provides a surge-current capability for small systems that must support intermittent radio transmissions or disk spin-ups. the main regulator (controlled by the lx terminal) contributes high efficiency during normal operation and also guarantees start-up at low voltage (its internal power mosfet has a gate-threshold voltage of 0.8v).
figure 1. this ic, designed as a power-supply controller for palmtop computers with flash memory, includes two switching regulators. combining the outputs with a diode-or connection and common feedback produces an efficient 5v output with surge-current capability.
the auxiliary surge-current regulator, on the other hand, has an external mosfet and is not limited to 5w. it can be tailored for heavier loads by substituting larger inductors and larger capacitors.
the chip offers a low-power mode that lowers the peak currents, which raises the light-load efficiency by 10% (figure 2).
figure 2. conversion efficiency in the figure 1 circuit depends on the operating mode and the input voltage.
in most cases, it's not a good idea to connect unsynchronized switching regulators in parallel: the oscillators can produce unwanted beat frequencies, and the load can monopolize current from one of the outputs. this circuit avoids such problems because the regulators differ greatly in switching frequency and output-current capability.
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combining the outputs of two simple boost regulators with a diode-or connection (figure 1) provides a surge-current capability for small systems that must support intermittent radio transmissions or disk spin-ups. the main regulator (controlled by the lx terminal) contributes high efficiency during normal operation and also guarantees start-up at low voltage (its internal power mosfet has a gate-threshold voltage of 0.8v).
figure 1. this ic, designed as a power-supply controller for palmtop computers with flash memory, includes two switching regulators. combining the outputs with a diode-or connection and common feedback produces an efficient 5v output with surge-current capability.
the auxiliary surge-current regulator, on the other hand, has an external mosfet and is not limited to 5w. it can be tailored for heavier loads by substituting larger inductors and larger capacitors.
the chip offers a low-power mode that lowers the peak currents, which raises the light-load efficiency by 10% (figure 2).
figure 2. conversion efficiency in the figure 1 circuit depends on the operating mode and the input voltage.
in most cases, it's not a good idea to connect unsynchronized switching regulators in parallel: the oscillators can produce unwanted beat frequencies, and the load can monopolize current from one of the outputs. this circuit avoids such problems because the regulators differ greatly in switching frequency and output-current capability.
嵌入式处理器市场，Intel不会是ARM的对手？
来访中国、牵手Arm，英特尔这头“大象”要转型
基于JTAG的星型扫描接口的设计及其仿真
韩国政府正式公布了该国5G技术的七年期增长计划
LM339的原理和应用
Dual Boost Regulator Handles H
消息称任天堂计划导入更先进的Mini LED显示技术
联发科凭天玑9300推动市场份额达到新高
简述SMT贴片加工制造务必做好的一些产前准备工作
Intel2020年第4季度总收入达到200亿美元
德赛西威徐建：以原子化整合服务打开智能座舱新未来
别人家的孩子：5岁学编程、8岁开发iOS应用程序
变换器的EMI是怎么辐射出去的
工业物联网为个性化领域带来新挑战和新风险
插电式混合动力汽车被重新定义，但不会那么快退出新能源汽车市场
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意法半导体扩大抗辐射航天用模拟芯片产品阵容
手机,折叠屏风口来了?
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DigiKey 在 2023 EDS 领导力峰会上斩获供应商授予的多项大奖