Publitek European Editors :
The low-dropout regulator (LDO) has long been the choice for buck voltage conversion not only where cost is an issue but where noise performance is critical.
The brainchild of Linear Technology co-founder Robert Dobkin, conceived when he worked at National Semiconductor, the core architecture of the regulator is very simple but effective. Dobkin took a fixed-ratio voltage regulator and adapted it so that its output could be adjusted using a voltage divider on the output.¹
In the classic linear regulator, a transistor acts as half of a potential divider. Its output voltage is to control a feedback circuit that has control over the transistor’s gate in the case of a MOSFET, which is normally the case for an LDO regulator. The constant control via feedback over gate voltage provides a stable output voltage at a level set by the reference circuitry. Because of the use of a voltage divider structure, the linear regulator can produce only a voltage that is lower than that of the input. Older regulator circuits could experience a drop of 2 V or more. LDOs were devised to provide easier control over the output voltage and to constrain this dropout voltage to less than 2 V.
Linear Regulators Drive Noise Down - [Link]
Tamara Schmitz writes:
Combining the operation of a boost regulator and a negative voltage converter can generate a negative supply from a single low-voltage supply. The circuit in Figure 1 shows a standard application circuit for a +20 V supply along with two op amps, two diodes and two capacitors to generate the – 20 V supply. This article will discuss the basic operation of a boost converter to generate a larger positive supply voltage. Equations are derived to determine the minimum inductor value to maintain a safe peak inductor current, and a maximum inductor value to maintain continuous conduction mode (CCM) operation. The article will then discuss the generation of a negative supply and the restrictions of the design.
Simple Circuit to Generate Plus and Minus Supplies Using a Boost Regulator - [Link]
All embedded systems require electric power to operate. Most of the electronic components inside them, including the processors, can operate at a wide range of supply voltage. For example, the operating voltage range for the PIC16F1847 microcontroller is 2 to 5.5 V. But there are certain applications where you need a regulated constant voltage to avoid malfunctioning of the circuit or getting erroneous results. For instance, any application that involves analog-to-digital conversion (ADC) requires a fixed reference voltage to provide accurate digital count for input analog signal. If the reference voltage is not stable, the ADC output is meaningless. Here is my latest dual power supply regulator board that provides constant 3.3V and 5.0V outputs from an unregulated DC input (6.5-10V). It is small in size and can be easily enclosed inside the project box along with a project circuit board. It can also be used to power test circuits on breadboard. The board uses two AMS1117 series fixed voltage regulators and receives input power through a DC wall wart or an external 9V battery.
Multi-purpose dual power supply (5.0V and 3.3V) regulator board - [Link]
Semiconductor memory, card readers, microprocessors, disc drives, piezoelectric devices and digitally based systems
furnish transient loads that a voltage regulator must service. Ideally, regulator output is invariant during a load
transient. In practice, some variation is encountered and becomes problematic if allowable operating voltage tolerances
are exceeded. This mandates testing the regulator and its associated support components to verify desired performance under transient loading conditions. Various methods are employable to generate transient loads, allowing observation of regulator response.
Load Transient Response Testing for Voltage Regulators - [Link]
A Switch Mode Power Supply circuit collection from Linear Technology. It covers 12 basic SMPS circuit categories: Battery, Boost, Buck, Buck-Boost, Flyback, Forward, High Voltage, Multioutput, Off Line, Preregulator, Switched Capacitor and Telecom. [via]
Switching regulator circuit collection - [Link]
The TPS54160 device is a 60-V, 1.5-A, step down regulator with an integrated high-side MOSFET. Current mode control provides simple external compensation and flexible component selection. A low ripple pulse skip mode reduces the no load, regulated output supply current to 116 µA. Using the enable pin, shutdown supply current is reduced to 1.3 µA.
2.5MHz DC/DC converter protect against 65-V transients - [Link]
The LTC®3605A is a high efficiency, monolithic synchronous buck regulator using a phase lockable controlled on-time constant frequency, current mode architecture. PolyPhase operation allows multiple LTC3605A regulators to run out of phase while using minimal input and output capacitance. The operating supply voltage range is from 20V down to 4V, making it suitable for dual, triple or quadruple lithium-ion battery inputs as well as point of load power supply applications from a 12V or 5V rail.
LTC3605A – 20V, 5A Synchronous Step-Down Regulator - [Link]
The LT8610 and LT8611 are 2.5A, 42V input capable synchronous step-down switching regulators. Synchronous rectification delivers efficiency as high as 96% while Burst Mode operation keeps quiescent current under 2.5µA in no-load standby conditions. A 3.4V to 42V input voltage range makes the parts ideal for automotive and industrial applications. Internal 3.5A switches can deliver up to 2.5A of continuous output current to voltages as low as 0.97V. The LT8611 includes all of the features of the LT8610, plus a built-in current sense amplifier with monitor and control pins, enabling accurate input or output current regulation and limiting.
LT8610 – 42V, 2.5A Synchronous Step-Down Regulator - [Link]
This dual power supply regulator board provides constant 3.3V and 5.0V outputs from an unregulated DC input (6.5-10V). It is small in size and can be easily enclosed inside the project box along with a project circuit board. It can also be used to power test circuits on breadboard. The board uses two AMS1117 series fixed voltage regulators and receives input power through a DC wall wart or an external 9V battery.
Dual power supply (5.0V and 3.3V) regulator board – [Link]
The TPS7A7100/200/300 low-dropout (LDO) voltage regulators are designed for applications seeking very low dropout capability (typically less than 100mV at 1-A load) with an input voltage from 1.5V to 6.5V. The TPS7A7100 offers an innovative, user-configurable output-voltage setting from 0.9V to 3.5V. The output is pin-programmable, which eliminates accuracy error due to the tolerance of feedback resistors used in traditional adjustable regulator designs.
Very Low Input – Programmable Output (0.9V to 5.0V) Low-Dropout Linear Regulators - [Link]