Examples will be given using design characteristics of Analog Devices LDO families 3. This article reviews the basic LDO topology, explains key specifications, and shows the application of low-dropout voltage regulators in systems. LDOs have also been used as band-aids for noise reduction, to solve voltage-regulation problems caused by electromagnetic interference (EMI) and printed-circuit board (PCB) routing, and to improve system efficiency by switching off unneeded functions. Dedicated LDOs must be added in the later stages of system development to power such optional items as camera modules, Bluetooth, WiFi, and other bolt-on modules. Many of the LDOs in today’s portable devices are integrated into multifunction power-management ICs 2 (PMICs)-highly integrated systems with 20 or more power domains for audio, battery charging, housekeeping, lighting, communications, and other functions.Īs portable systems rapidly evolve, however, the integrated PMIC cannot keep up with peripheral power requirements. Nowadays, portable devices often require up to 20 low-dropout linear regulators. The adjustable-output low-dropout regulator 1 first came to public attention in 1977. This difference, known as the dropout voltage or headroom requirement, can be as low as 80 mV at 2 A.
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How to Successfully Apply Low-Dropout RegulatorsĪ low-dropout regulator (LDO) is capable of maintaining its specified output voltage over a wide range of load current and input voltage, down to a very small difference between input and output voltages.
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