Ivan Sergeev writes:
A switched capacitor / charge pump boost converter works by repeatedly charging a flying capacitor to an input voltage source and then stacking it on top of the input voltage source. This is achieved in the ideal schematic above by closing alternate switch pairs SW1/SW4 and SW3/SW2. When SW1/SW4 are closed, C1 is charged to voltage source V1. When SW3/SW2 are closed, C1 is stacked on top of voltage source V1. After some start up time, the big hold-up capacitor C2 is charged to 2*V1, and the load R sees roughly 2*V1 provided that it does not pull the charge out of C2 faster than it is replenished.
Discrete Switched Capacitor Boost Converter - [Link]
This reference design from Maxim is a current controlled boost driver designed for long strings of LEDs. Driving many LEDs in series has advantages over driving them in parallel. In a parallel configuration each LED will need it’s own current limiting resistor or current control, while the series LEDs make use of a single current controlled power supply. The driver must support the combined voltage of all the LEDs in the string. The reference design can supply up to 100 volts, which translates to around 30 LEDs.
App note: Current controlled boost driver for long LED strings - [Link]
Open EVSE is a Open Source Hardware/Software for charging an Electric Vehicle using the standard J1772 protocol. J1772 is used in the latest generation of EVs such as the Nissan Leaf, Plug in Prius and the Chevy Volt.
Open Electric Vehicle Supply Equipment (EVSE) - [Link]
Don Scansen writes:
Untapped energy surrounds us. Transducers to convert various energy sources into electricity that can be put to useful work are relatively straightforward to understand and implement. However, harvestable energy sources are intermittent, or at least very inconsistent, in terms of output. Many can provide only a few microwatts. Putting these very low energy sources to use requires efficient charge control electronics designed for low power.
In terms of performance, one of the most attractive energy harvesting power management ICs (PMIC) on the market is the MAX17710G+T from Maxim, which was designed from the ground up for energy harvesting and extracting the greatest amount of energy possible from the transducer element. As a result, it offers class-leading performance for this application. The PMIC allows very simple, low-cost solutions for battery charging and protection. The MAX17710G+T will provide good battery charging performance for a wide range of ambient sources and conditions. Useful power is extracted from levels as low as 1 µW and 0.8 V. Coupled to a very small form factor MEC (micro energy cell), it is a powerful combination for a broad range of energy harvesting applications.
A Hands-on Look at the Maxim MAX17710 Energy Harvesting PMIC - [Link]
This is an app note from Maxim describing how to protect your Lithium Ion batteries from reverse insertion into the charger. The circuit is a Li-Ion battery charger with an added analog comparator designed to detect when then battery is inserted the wrong way and disconnect it from the charger. [via]
Combining a linear-mode single-cell lithium-ion battery charger (MAX1551) with a comparator (MAX9001) and n-channel FET adds a layer of reverse-battery protection that protects a single cell lithium-ion battery charger and battery from damage due to backwards insertion
Protect your batteries from reverse insertion - [Link]
In 2010 Maxim acquired Teridian Semiconductor to create a device portfolio for Smart Metering applications. Recently a new device was added, the 78M6631, which is a highly integrated three-phase power measurement and monitoring system-on-chip (SoC) with a 10 MHz 8051-compatible processor core. Designed for a wide variety of applications requiring three-phase power and quality measurements, it is available with preloaded firmware that supports both delta and wye (Y or star) three-phase configurations. [via]
3-Phase Power Monitor on a Chip - [Link]
Paul Asselin has written a description of his design of a USB Lithium Polymer battery charger – [via]
I wanted to build a cheap USB LiPo charger and didn’t like the unavailability nor the price of the Maxim’s MAX1555. Searching for something better, I stumbled upon the Microchip MCP73831. It is still way too expensive in single quantities but there ain’t too many options.
The board is intentionally small and has a status LED. There really isn’t much more to it, it’s a single purpose device and just does the job. It is proudly Open Source Hardware.
Here is a simple programmable load. It’s basically a constant current sink that is controlled through a pot. The current is sunk through a high power FET which needs to be cooled to function properly – [via]
Here’s a link to a *really* simple linear constant current sink i put together
This design is about as simple as it gets. . .multi-turn pot controlled and readout done by a voltmeter:) The good news is that it works quite well for moderate loads. It was put together to regulate current flowing through a copper electroplating tank. Due to the monstrous Pentium II (or maybe III?) heat sink, it isn’t noticeably warm when eating 9A of current.
Simple analog programmable load - [Link]
Here is an interesting project which uses capacitors to store energy instead of chemical,sit uses an different type of capacitors called Goldcap capacitors,GoldCap capacitors offer an interesting alternative power source when compared to conventional disposable or even rechargeable batteries. They can be charged very rapidly and can also deliver a high peak output current. Their voltage rating however is quite low so a little electronic assistance is necessary to raise the output voltage to a more useful level.PP3 (6F22) type 9 V batteries are often used in small portable equipment that require very little current and may only be used intermittently. Under these conditions its often the case that the battery is flat just when you urgently need to use the equipment. NiCd rechargeable cells are not a good choice in these applications because their self-discharge characteristics are much worse than dry cells and often there is no charge left after a long time in storage.
Superfast Rechargable Battery - [Link]
Don Scansen writes:
The viability of an energy harvesting application often depends on components that can efficiently extract very low levels of power at low current and/or low voltage, and deliver these to a storage battery or capacitor. The premise is simple: scavengers of ambient energy rely only on what they are given and what is available, sometimes more, sometimes less.
This self-evident truth places great importance on products such as step-up low voltage boosters, which are self-powered modules that convert a low DC voltage input to a higher AC or DC voltage output suitable for low-power energy harvesting applications using photodiodes, thermoelectric or electromagnetic generators as the input source.
Step-up Micropower Voltage Boosters Simplify Energy Harvesting - [Link]