by DAVID BURGOON @ edn.com:
There are several ways to produce a negative voltage from a positive voltage source, including using a transformer or two inductors and/or multiple switches. However, none are as easy as using the LTC3863, which is elegant in its simplicity, has superior efficiency at light loads and reduces parts count compared to alternative solutions.
The LTC3863 can produce a –0.4V to –150V negative output voltage from a positive input range of 3.5V to 60V. It uses a single-inductor topology with one active P-channel MOSFET switch and one diode. The high level of integration yields a simple, low parts-count solution.
AppNote: Inverting DC/DC controller converts a positive input to a negative output with a single inductor – [Link]
By Chris Glaser @ ti.com:
Especially for switch-mode power supplies (SMPSs), the printed circuit board (PCB) layout is a critical but often under appreciated step in achieving proper performance and reliability. Errors in the PCB layout cause a variety of misbehaviors including poor output voltage regulation, switching jitter, and even device failure. Issues like these should be avoided at all costs, since fixing them usually requires a PCB design modification. However, these pitfalls are easily circumvented if time and thought are spent during the PCB layout process before the first PCBs are ever ordered. This article presents five simple steps to ensure that your next step-down converter’s PCB layout is robust and ready for prototyping.
Five steps to a great PCB layout for a step-down converter – [Link]
by Steve Taranovich @ edn.com:
Linear Technology Corporation just announced another in its series of power management ICs for automotive usage, the LT8640, a 5A, 42V input capable synchronous step-down switching regulator. A unique Silent Switcher™ architecture, combined with spread spectrum frequency modulation, reduces EMI/EMC emissions by more than 25dB even with switching frequencies in excess of 2MHz, enabling it to easily pass the automotive CISPR25, Class 5 peak limits. This feature varies the clock with a triangular frequency modulation of +20%.
Silent Switcher with high efficiency and low EMI/EMC – [Link]
by Susan Nordyk @ edn.com:
A synchronous PWM controller for negative-to-negative or negative-to-positive DC/DC conversion, the LT8709 from Linear Technology is easily configured for buck, boost, buck-boost, and inverting topologies to accommodate a wide range of power-supply designs. The device’s synchronous operation means that the output diode is replaced with a high-efficiency P-channel MOSFET, increasing efficiency and allowing for higher output currents of up to 20 A. It also eliminates the heat sink typically required in medium- to high-power applications.
The LT8709 operates over an input range of -4.5 V to -80 V and produces an output from -0.1 V to as high as 60 V or from -1.4 V to as low as -80 V. Its rail-to-rail output-current monitor and control enable the device to be configured as a current source. The controller has an EN/FBIN pin that accepts slowly varying input signals, as well as an adjustable undervoltage lockout function.
Buck/boost/inverting controller delivers up to 20 A – [Link]
Linear Technology announces the LT3790, a synchronous buck-boost DC/DC controller that delivers up to 250 W of power with a single IC. Its 4.7 V to 60 V input voltage range makes it ideal for a wide variety of automotive and industrial applications. Its output voltage can be set from 0 V to 60 V, making it well suited as a voltage regulator or battery/supercapacitor charger. The LT3790’s internal 4-switch buck-boost controller operates from input voltages above, below or equal to the output voltage, making it ideal for applications such as automotive, where the input voltage can vary dramatically during stop/start, cold crank and load dump scenarios. Transitions between buck, pass-through and boost operating modes are seamless, offering a well regulated output in spite of wide variations of supply voltage. The LT3790’s unique design utilizes three control loops to monitor input current, output current and output voltage to deliver optimal performance and reliability.
60V, Synchronous Buck-Boost Controller – [Link]
The LMR16006 is a PWM DC/DC buck (step-down) regulator. With a wide input range of 4 V to 60 V, it is suitable for a wide range of application from industrial to automotive for power conditioning from an unregulated source. The regulator’s standby current is 28 µA in ECO mode, which is suitable for battery operating systems. An ultra low 1 µA shutdown current can further prolong battery life. Operating frequency is fixed at 0.7 MHz (X version) and 2.1 MHz (Y version) allowing the use of small external components while still being able to have low output ripple voltage. Soft-start and compensation circuits are implemented internally, which allows the device to be used with minimized external components. The LMR16006 is optimized for up to 600 mA load currents.
LMR16006 SIMPLE SWITCHER 60V Buck Regulators with High Efficiency ECO Mode – [Link]
App note(PDF) from NXP on DC-DC medium power small-signal MOSFETs.
This application note explores different methods of DC-to-DC conversion. It includes some examples of DC-to-DC down-converters using small-signal MOSFETs.
App note: Medium power small-signal MOSFETs in DC-to-DC conversion – [Link]
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]
Linear Technology Corporation announces the LTC3371, a highly integrated general-purpose power management solution for systems requiring multiple low voltage power supplies. The device features four synchronous buck converters, each powered from independent 2.25 V to 5.5 V inputs, and each configurable to share up to four of eight available 1 A power stages. With eight unique output current configurations, the LTC3371 provides substantial flexibility and ease of reuse across many different applications. The device is ideal for a wide variety of multichannel industrial, automotive, communications and distributed power systems.
Configurable Buck DC/DCs Deliver a Total of 8A from 2 to 4 Independent Outputs for Power System Flexibility – [Link]
Switch-mode regulator Traco TSR 0.5 will give you as much as you need. If you have an application, where 0.5A is sufficient, then the new series of DC/DC modules is ideal for you.
Maybe, it´s worth to ask a question, whether it makes sense to use a switch-mode regulator for such a low current? For sure yes, at least because of two reasons. If we need to create 3.3V from for example 12V, then at a current of 0.5A a power loss of 4.35W appears at a classic linear regulator. That´s already a quite considerable power, able to heat up a device – especially at smaller enclosures and a dense population on a PCB.
Another reason is energy saving – especially at battery powered devices. Switch mode power supplies (SMPS) have a “genial” feature, that thanks to their high efficiency we use practically whole power drawn from a source, i.e. if we need say 5V/0.5A from a 15V source – we won´t take from it 0.5A but only approx. 0,17-0,18A.
Novelty of company Traco Electronic – series TSR 0.5 is by its function very similar to well known, proven DC/DC regulators TSR1 or TSRN1. The main difference is in a smaller allowed current and a feelingly lower price . That ´s why this series is very suitable for any application, where a current of 0.5A will be sufficient. A big advantage can be a wide operating temperatures range from -40 to +90°C (power derating 5%/K at temperature above 80°C). Maximum input voltage of 32V enables a usage even at power supplying from various alternative energy sources with a big input voltage fluctuations.
This novelty is so far available in a version with 5V output voltage (TSR 0.5-2450) and soon there will be another.
Why to pay for the current, which you won´t use? – [Link]