Susan Nordyk @ edn.com:
Encapsulated in a tiny 9.0×6.5×1.83-mm QFN package, the ISL8203M step-down DC/DC power module from Intersil furnishes an adjustable output voltage between 0.8 V to 5 V to allow designers to use one device to build a single 6-A or dual 3-A output power supply. The ISL8203M simplifies power-supply design for FPGAs, ASICs, microprocessors, DSPs, and other point-of-load conversions in communications, test and measurement, and industrial systems.
Intersil shrinks step-down DC/DC power module – [Link]
Insulating DC/DC modules TRACOPOWER TRV 1 series with a high insulation strength, provide a semi-regulated output in a miniature SIP package.
Series TRV1 is suitable everywhere, where you need a galvanically isolated supply with a maximum power of 1 Watt and with miniature dimensions. But TRV1 brings 2 bonuses – 3000V insulation strength and a semi-regulated output. Unlike the most simple DC/DC modules, TRV 1 provide a relatively stable output voltage, changing with the 10-90% load only in approx. 5%. At the same time, Industry standard pinout gives a promise for a long-term stable production of your devices.
Traco TRV 1 series consists of 3 groups with different input voltage – 5, 12 and 24VDC. In every group can be found 4 types with the output voltage of 5, 9, 12 or 15VDC. It means, that TRV 1 series contains both step-down and step-up types. TRV 1 series models feature a high efficiency of 84 to 87%, what enables their usage in -40 to 85°C temperature range without power derating. Also a reliable operation is guaranteed up to 5000m altitude. Detailed information will provide you the TRV 1 datasheet.
Traco TRV 1 isolates up to 3000V – [Link]
Sergei Bezrukov writes:
Some multimeters use 9V block batteries which do not last long and are relatively expensive compared with other alkaline battery types. If the multimeter is used extensively one need to replace batteries pretty often. A more practical solution would be to power the multimeter from AA or AAA batteries and use a DC-DC converter to obtain 9V from 3V.
The converter is based on the power supply controller TL499A manufactured by Texas Instruments and the schematics follows the standard one from the data-sheet. The only difference is attaching a LF filter to pin 3 consisting from a 10 Ohm resistor and a 1μF capacitor. This idea is taken from a similar project published in June 2007 issue of Everyday Practical Electronics and it significantly reduces the voltage peaks at the output. The inductor is Murata 18R473C.
9V DC-DC converter for a multimeter – [Link]
3-to-9V booster – [Link]
The diagram sums up our own approach nicely as well. When working with any buck or boot converter, we:
- Keep the main power path (shown in blue) straight and compact. We always use an extra wide trace or even a polygon. It’s surprising how often you find boards that use a dainty 16mil trace, it should be 5 to 10 times bigger.
- Supply capacitors Cin1 and Cin2 should be as close to the switch input as possible. The switch is usually a FET, in this case it is inside the chip.
- The buck or boost parts (L1, D, Cout) should be snuggled right up against the switch output in a straight, clean path. The MAX16974/MAX16975/MAX16976 high-performance DC-DC converters are standard buck controllers designed for automotive applications. This application note explains how to optimize the layout of these ICs. An example layout is provided at the end of the document.
App note: Layout guidelines for DC/DC switching power supplies – [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]
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]
The app note featured here provides basic PCB layout tips for building switch-mode DC/DC converters. As an integral part of their function, switch mode converters have square like signals in some of their traces. These signals create harmonics from the switching frequency that can cause much EMI interference, as well as decreased stability of the converter. [via]
This note by Maxim helps eliminate these and some other issues that might arise form using switch-mode converters.
- Place and route the power components. Start placing switching transistors Q1 and Q2, inductor L, and input and output capacitors CIN and COUT. Arrange them so as to minimize the distances between them, in particular the ground connections of Q2, CIN and COUT, and the CIN and Q1 connection. Next, create top-layer shapes for the power ground, input, output, and LX nodes, and route them on the top layer using wide short traces.
- Place and route the low-level signal components. The controller IC should be placed close to the switching transistors. Low-level signal components are placed on the other side of the controller. High-impedance nodes are kept small and away from the LX node.
- Create an analog ground shape on a suitable layer and connect it to power ground at one point.
App note: Board layout tips for switchmode DC/DC converters – [Link]
The schematics for this DC/DC converter is built around the UC3843 generic, low cost PWM controller. This very common PWM controller generate a duty-cycle modulated square wave ranging from 0 to 100%, at a user fixed frequency of 100KHz.Here are some features: [via]
- Input voltage from 10V to 18V
- Output voltage from 20V to 28V adjustable
- Output current up to 5A for 3300mAh battery packs fast charge.
- Compact dimension (80×60mm)
- No heat sink or fan coolers even delivering up to 140W to the load.
High power 24V DC/DC converter – [Link]
MAKE Flickr Pool member Funax made an Arduino-compatible board powered by a single AAA battery. A step-up converter is used to boost the battery’s 1.5V output to 5V and meet Arduino’s minimum power requirements. Keep in mind – this circuit would considerably reduce current supplied to the board and therefore limit its ability to power external components.
AAA powered Arduino – [Link]