Publitek European Editors writes:
Many security and motion detector systems rely on small, semi-autonomous nodes that are easy and simple to install. This implies the use of a battery-based power source and low-power operation in order to minimize the number of battery changes during the lifetime of the product.
Over its lifetime, the output voltage of a battery falls, with the biggest decline when the charge is nearing full depletion. A converter type that can accommodate this change in voltage but can still provide relatively high voltages for sensors and RF transmitters is the buck-boost converter – it operates the buck part of the circuit when the battery is fresh, moving to boost operation when the voltage falls below the threshold of the electronic circuitry it powers. A number of vendors have developed integrated buck-boost converters optimized for battery systems
Buck-Boost Converters Help Extend Battery Life for Motion Detection - [Link]
Giorgos @ PCBheaven build a MCP1640 boost converter for the next LED light project. This converter can be used with almost dead batteries and will squeeze any remaining energy from them. [via]
What i want now, is something to spice up this hack. So here is what – I used the MCP1640 boost converter to drain the last electron from the batteries. This chip can work with a ridiculous low voltage and provide enough power to drive a couple LEDs. Which means the 2 AA batteries will operate even longer and the LEDs will be much brighter.
High efficiency battery boost regulator using the MCP1640 - [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]
Current controlled boost LED driver and black soldermasks @ Limpkin’s blog – [via]
[Here's] all you need to know to design your own LED driver based on the MAX16834 and also give you the design spreadsheets that are quite long to get.
Current controlled boost LED driver and black soldermasks - [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]
This reference design is for a high-voltage boost current source for very long strings of LEDs. Applications that use long LED strings include, but are not limited to, streetlights and parking garage lights. Long LED strings can be a very cost-effective way to drive LEDs. Also, since the LEDs will have exactly the same current, brightness variations are nicely controlled. This design has a 24V input, up to a 75V LED output, and drives 1.5A through the LED string (or strings, if paralleled). The measured input power is 115.49W and the output power is 111.6W for an efficiency of about 96.6%.
112W Boost driver for long strings of LEDs - [Link]
Here is a part from National Semiconductor designed for controlling high-power DC/DC boost regulators. What makes it interesting is that its PWM frequency can be pushed to 2Mhz. This allows for smaller and cheaper discrete components, like inductors and capacitors. The datasheet on this device also provides some nice PCB guidelines to maximize its efficiency and minimize noise.
App note: LM5022 DC/DC boost controller - [Link]
Here is an article from Texas Instruments featured on EETimes describing how to design a buck-boost converter. These converters are used when the input voltage can be both above and below the output voltage. One example are 3.3V systems powered by lithium-ion batteries which swing from ~3V to ~4V.
This design is in effect a combination of both buck and boost reference designs. When the right switch is left open and control is applied to the left switch a buck converter is made. Vice-versa, when the left switch is left closed and control is applied to the right switch a boost converter is built.
App note: Buck-boost converter - [Link]
Here is an app note from Maxim describing how to implement a digital potentiometer to adjust the output of a boost converter. Digipot is controlled through two push buttons. One controls the direction of the wiper, while the other moves the digipot wiper in the selected direction. [via]
The digipot is implemented on the DC/DC boost converter’s feedback loop, adjusting one of the resistors in the loop.
Connecting the wiper of IC1 via a 10k resistor to the FB node of IC2 sets that feedback according to the voltage on IC1′s wiper. The equation for setting the output voltage precisely is a complex one that includes the resistances of the feedback resistors and of the digipot, but it can be simplified by calculating voltages at the extremes of the wiper setting.
App note: Pushbuttons Control Regulated Switching Converter - [Link]
Luca is building a Nixie clock, and in this post he covers the high voltage power supply section.
Nixie tubes are digit displays that use ~170V between the digit wire and a wire mash, to agitate the gas inside the tube. This surrounds the digit wire with a orange glow and it becomes visible through the tube.
Luca is using the MAX1771 based DC/DC boost converter to supply the high voltage required. This DC/DC steps up the 9-12V input to 180V output, as a bonus it has an additional 5V output for the rest of the circuit board.
Nixie clock HV power supply - [Link]