A guide to selecting the most suitable LDO for your application

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A guide to selecting the most suitable LDO for your application

LDOs may seem simple, but in order to select the optimal LDO for your application it is important to know a bit more about these devices. In this newsletter and tutorial videos you’ll learn some interesting details about the inner working of these parts including key selection criteria, design tips and an overview of Richtek’ popular LDO product family.

What is a Low Dropout Linear Regulator?

Low dropout basically means that the LDO can still regulate the output voltage, even when the input voltage is very close to the output voltage. But what is the difference between a PMOS type LDO and a NMOS type LDO? Why is it better to choose a NMOS type LDO for applications with Vin lower than 2.5V? In which applications can an LDO replace a Buck converter? Find out more in the tutorial video.

LDO Power Dissipation and Thermal Design

To get the most out of your LDO application, the LDO power dissipation needs to be carefully considered. The power dissipation in the LDO is determined by the voltage drop across the LDO multiplied by the current passing through the LDO. Increasing the LDO voltage drop or the LDO current quickly leads to higher dissipation. But how much power can you dissipate in the LDO? Learn more about package power dissipation and how to improve your thermal design in our tutorial video.

LDO Dropout Voltage

LDOs are Low Drop-Out Linear regulators. But what exactly does Low Dropout mean? How well does an LDO regulate the output voltage when the input voltage is very close to the output voltage? Our tutorial video will explain the LDO dropout operation and dropout curves, and gives a practical measurement example of the RT9187 LDO close to dropout operation.

LDO as Ripple Suppressor

Learn why Richtek ultra low I_Q LDOs use dynamic quiescent current control for obtaining the best performance in battery powered applications requiring long battery life.

Ultra Low I_Q LDOs

Learn why Richtek ultra low IQ LDOs use dynamic quiescent current control for obtaining the best performance in battery powered applications requiring long battery life.

Richtek LDO family

For more information, please find the LDO landing page in the "power management introduction and selection guide"

New Products

RT2101A is an Automotive Grade 2.95V-6V input, 3A I_OUT synchronous Buck converter in WQFN-16L 3x3 package with adj. F_SW 700kHz to 2MHz, external sync. pin and PGood indicator, producing stable low voltage supplies in harsh environments.

RT9069 is a 2μA I_Q, 3.5V-36V input, 200mA LDO with Enable, supporting fixed V_OUT (2.5V, 3.3V, 5V, 9V and 12V), ideal for industrial and battery-powered devices.
Also see other low I_Q LDOs.

RT7238B/C/D are high current Buck converters with wide input voltage range and include an LDO for low power standby function. 8V-23V input, 8A current, 500kHz with fixed 3.3V/5V 70mA LDO in UQFN-10L 3x3. ACOT® topology makes it a great choice for applications which require ultra-fast transient response.

RT9088 is a high performance DDR termination regulator, offering ultra fast transient and low dropout in sink and source mode for very stable DDR voltage. Supporting +/-3A in DDRI/DDRII/ DDRIII, +/-2.5A in LPDDRIII & DDRIV with S3 off mode, PGOOD, MLCC stable, remote sense and REFIN input in WDFN-10L 3x3 packages.

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