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Power Supplies:  DC to DC / Switch Mode and DC to DC Converters
Boost,    Buck,    Buck-Boost,    Switchmode

Power Supplies -- Main Page           Converters -- Main Page
DC to DC:  #'s - A       B - D       E - L       M - R       S - Z

Last Updated: October 18, 2017 05:04 AM

Circuits Designed by Dave Johnson, P.E. :

Simple Circuit Negative Supply Circuit - This simple circuit consists of two LEDs and a photo diode.  It generates a negative voltage with a current level of a couple milliamps.  It is ideal for supplying a negative rail to low power “rail to rail” op amp circuits, which need to have a true zero volts output.  Note:  This circuit is not particularly efficient . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

 Square Wave Driver Has Flexible Outputs - This circuit can produce an output signal ranging from DC to 100KHz.  It can source a voltage ranging from 1v to 30v.  It can sink a voltage ranging from zero volts to –30v.  It can drive up to 200ma of current and can even be switched to a floating tristate. . . Circuit by Dave Johnson P.E.-July, 2000

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-368-7747

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

Solar Charge Controller -  PiC Project  The previous version of this device used pulse width modulation (PWM) to control the power from the five solar panels to charge the battery bank.  Under full sun conditions the MOSFETS got a bit warm and the whole unit radiated a lot of RFi.  This design uses a set of relays, one for each panel.  if the controller decides the battery voltage is too low, it engages another relay;.)  __ Designed by Luhan Monat-Mesa Arizona

Solar Step Down Regulator -  This is an experimental circuit which rapidly "chops" a steady DC input voltage to produce a lower output voltage. Regulation is a function of the chopping - It is caused by the output transistor switching on and off around the target voltage, which when smoothed provides a constant DC output. __ Designed by Rowan from Melbourne, Australia

Solar-Cell Converter Offers Positive Start-Up -  08/15/96 EDN Design Ideas:  Applications deriving power from solar cells often require a 5V power supply.  However, the cells typically provide a terminal voltage of only 0.8 to 1.4V with current capacity of 3 to 4A.  Most DC/DC converters can neither start with such low voltages, nor can they start under full-load conditions.  The two-iC approach __ Circuit Design by Robert Badalian, Maxim Integrated Products, Sunnyvale, CA

Solar-Powered 2.2V Supply & 1.8V LDO with Li Battery Backup & Run Threshold Set to Battery Minimum Voltage -  The LTC3104 is a high efficiency, monolithic synchronous step-down converter using a current mode architecture capable of supplying 300mA of output current.  The LTC3104 includes an integrated, adjustable 10mA LDO to power noise sensitive functions.  Additionally, the LTC3104 includes an accurate RUN comparator, thermal overload__ Linear Technology/Analog Devices App Note, Dec 5th 2011

Solar-Powered 2.2V Supply with Li Battery Backup & Run Threshold Set to Battery Minimum Voltage -  The LTC3103 is a high efficiency, monolithic synchronous step-down converter using a current mode architecture capable of supplying 300mA of output current.  Additionally, the LTC3103 includes an accurate RUN comparator, thermal overload protection, a power good output and an integrated soft-start feature to guarantee that the__ Linear Technology/Analog Devices App Note, Dec 5th 2011

Soldering surface Mount components -  Coilcraft RF Magnetics App Note- __ Designed by Coilcraft Power Magnetics Application Note

Some Thoughts on DC/DC Converters -  AN29 Linear Technology This note examines a wide range of DC/DC converter applications.  Single inductor, transformer, and switched-capacitor converter designs are shown.  Special topics like low noise, high efficiency, low quiescent current, high voltage, and wide-input voltage range converters are covered.  Appended sections explain some fundamental properties of different types of converters.  __ Linear Technology/Analog Devices

Some Thoughts on DC-DC Converters -  Linear Technology AN29 __ Designed by Jim Williams - Oct 1st, 1988

SOT-23 DC/DC Converters Generate Up to ±35V Outputs & Consume Only 20µA of Quiescent Current -  DN223 Design Notes __ Linear Technology/Analog Devices

Split Supply Generator -  Occasionally a designer needs a dual power supply to power a circuit that is operating with signals near or at ground but the only available supply is a single polarity, usually positive.  Many excellent IC solutions are available but a suitable solution for many projects may be constructed from "junk box" parts.  The simple circuit below will generate about 9 volts and -4 volts from a single 5 volt supply with sufficient current to power a simple op-amp circuit.  The positive voltage drops to about 7 volts when supplying 7 mA and the negative voltage drops to about 3.5 volts when supplying 3.5 mA (1k loads).  Although this isn't exactly a +- 15 volt supply, this is plenty of voltage and current for many op-amp circuits and will allow the output of most op-amps to swing below zero volts and will allow most op-amp inputs to measure voltages below zero volts.  This circuit uses the CD4049 which is a high current version of the CD4069 which will also work with somewhat lower current capability.   __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Spreadsheet simplifies switch-mode power-supply flyback-transformer Design -  EDN  Design ideas - 03/14/1997    Designing flyback transformers for switch-mode power supplies involves many calculations.  A spreadsheet can make short work of this otherwise-tedious task. __ Circuit Design by Brooks Leman, Power Integrations

Square Wave Driver Has Flexible Outputs -  This circuit can produce an output signal ranging from DC to 100KHz.  it can source a voltage ranging from 1v to 30v.  it can sink a voltage ranging from zero volts to –30v.  it can drive up to 200ma of current and can even be switched to a floating tristate. . . Circuit by Dave Johnson P.E.-July, 2000

Stacked Supercap Charger from 2.5V to 5V Input to 4.5V Output -  The LTC3125 is a high efficiency, synchronous step-up DC/DC converter with an accurate programmable ±5% accurate average input current is resistor programmable and suitable for a wide variety of applications__ Linear Technology/Analog Devices App Note, Mar 24th 2010

Stacked Supercapacitor Charger from 1.8V to 5.5V Input to 5V Output (1000mA Max Input Current)  -  The LTC3127 is a wide ViN range, highly efficient, 1.35MHz fixed frequency buck-boost DC/DC converter that operates from input voltages above, below or equal to the output voltage.  The LTC3127 features programmable average input current limit, making it ideal for power-limited input sources.  The input current limit is programmed with a single resistor and is accurate from 0.2A to 1A of average input current.  __ Linear Technology/Analog Devices App Note, Mar 24, 2010

Starpower-A Switching Supply for Luxeon Star LEDs -  it's based on a switching regulator ic, runs of 12V and is just the shot for powering 1-5W Luxeon Star LEDs.__ SiliconChip

Step Up/Step Down Converter Takes 2 to 16V Inputs -  07/16/98 EDN Design Ideas:  (Several circuits in this file.  Scroll to find this one) The circuit in Figure 1 is a low-cost step-up/step-down dc/dc converter.  By definition, its input can range above and below the regulated voltage.  The circuit includes a simple switchmode boost converter (iC1) that contains a comparator normally used to detect low battery voltage.    __ Circuit Design by Lucian Brodogna and  Luca Vasalli/ Maximin Integrated Products, Milan Italy

Step up/step-down current-source charges batteries -  06/06/96  EDN Design Ideas:  For battery charging, the highly efficient step-down (buck] configuration is usually the topology of choice.  However, a different approach is necessary if the following conditions prevail. The supply voltage is less than the battery  __ Circuit Design by Michael Keagy, Maxim Integrated Products, Sunnyvale, CA

Step-Down Conversion Concept for a PWM-Mode Boost Converter -  Ti App Note __ 

Step-Down Converter Operates from Single Li-ION Cell -  DN196 Design Notes__ Linear Technology/Analog Devices

Stepdown Converter Uses a Ceramic Output Capacitor -  12/31/69 EDN Design Ideas:  Many stepdown (buck) dc/dc-converter ICs incorporate a voltage-mode-control algorithm.  As a result, for stable operation in continuous-conduction mode, the application circuit's output capacitor is normally a high-ESR tantalum type for two reasons.  The portion of output ripple due to ESR provide as the current-mode signal that's necessary for cycle-to-cycle stability.  in the frequency domain, this capacitor also provide as a zero that cancels a pole in the buck converter's second-order LC filter, thereby shifting operation back to the stable region by reducing the ripple's phase shift to less than 90°.    __ Circuit Design by Karl R Volk, Maxim Integrated Products, Sunnyvale, CA

Step-Up Supply Charges Battery While Serving Load -  06/08/95 EDN Design Ideas:  The circuit in Fig 1 supports portable applications in which a microprocessor controls battery charging.  Step-up switching regulator iC1 boosts ViN (5V]to supply a combination of charging and load current. (Note that the 5V source  __ Circuit Design by Dana Davis, Maxim Integrated Products, Sunnyvale, CA

Step-Up/Step-Down DC/DC Conversion Without Inductors -  DN189 Design Notes __ Linear Technology/Analog Devices

Student DC Power Supply -  Build a simple DC supply having three output terminals: regulated +5VDC, unregulated +10VDC and 7.5VAC.  The supply is suitable for microcontroller experimenting.   __ Designed by Wichit Sirichote

Super wide bandwidth power splitters ZN2PD2-50, ZN4PD1-50 -  AN-10-003 App Note__ MiniCircuits.com

SuperCap Backup Power -  The LT8582 is a dual independent channel PWM DC/DC converter with a power good pin and built-in fault protection to help guard against input overvoltage and overtemperature conditions.  Each channel consists of a 42V master switch and a 42V slave switch that can be tied together for a total current limit of 3A.  __ Linear Technology/Analog Devices App Note, Jan 16th 2012

Supercapacitor boosts current from small battery -  09/02/04  EDN Design Ideas:  Some battery-powered devices require large amounts of current in a short period of time but spend most of the time in sleep (power-down] mode.  The momentary large-load current demands large batteries to meet the time requirement, eve __ Circuit Design by Yongping Xia, Navcom Technology, Torrance, CA

Supply converts 5V to-48V -  11/24/99 EDN Design Ideas:  As the demand for networking equipment grows, the need arises for a-48V supply that can power telecommunication lines.  The circuit in Figure 1 delivers 24W at-48V from a 5V input.  One of the biggest challenges in this design is choosing the input voltage.    __ Circuit Design by Kurk Mathews

Supply Derives 5 & 3.3V from USB port -  20-Dec-01 EDN Design Ideas:  The circuit in Figure 1 derives its power from a USB port and produces 5 and 3.3V supply rails for portable devices, such as digital cameras, MP3 players, and PDAs.  The circuit allows the port to maintain communications while, for example, charging a lithium-ion battery.  iC2 boosts the battery voltage, VBATT, to 5V, and iC3 buck-regulates that 5V output down to 3 __ Circuit Design by Chad Olson, Maxim Integrated Products, Sunnyvale, CA

Supply uses AC to generate 5V, power-on reset -  05/16/02 EDN Design Ideas:  The need often arises for a low-cost logic supply for powering microcontrollers and related circuitry in "white-goods" products, such as industrial controllers and sensors.  These applications usually include 24 or 115V ac or higher levels of ac voltage for conversion to 3.3 or 5V dc.  The simplest approach to generating low-current logic-supply levels is to apply the rectified and filtered ac in __ Circuit Design by Greg Sutterlin, Maxim Integrated Products, Sunnyvale, CA

Supply Voltage Indicator -  This simple and slightly odd circuit can clearly show the level of the supply voltage (in a larger device) : as long as the indicator has good 12 volts at its input, LED1 gives steady, uninterrupted (for the naked eye) yellow light.  if the input voltage falls below 11 V, LED1 will start to blink and the blinking will just get slower and slower if the voltage __ Designed by Miroslav Adzic-Serbia & Montenegro

Supplying Power via the1 Wire Bus -  App Note #949__ Maxim Integrated

Surface Mount DC/DC Converter Delivers 100A -  DN215 Design Notes__ Linear Technology/Analog Devices

Switched-Capacitor Integrator -  We can strap this circuit onto the front end of an OpAmp to create the basic building block of many filter circuits the integrator.  However, the major obstacle to happy filtering is the mine field of stray capacitance.  These uncontrolled strays can add significant capacitance to the switched capacitor, destroying the accuracy of your desired filter  __ Designed by Rick 

Switched-Capacitor Low Pass Filters for Anti-Aliasing Applications -  DN16 Design Notes__ Linear Technology/Analog Devices

Switched-capacitor regulator provides gain -  A switched capacitor voltage inverter is normally used to generate a negative supply voltage from a positive input supply.  The negative supply current is equal in magnitude to the current drawn from the input.  This Design idea   describes two circuits that use an inverter to double the current between the input and output, increasing efficiency and eliminating heat dissipation problems.   __ Designed by Jeff Witt, Linear Technology/Analog Devices Corp, Milpitas, CA

Switched-Capacitor Voltage Multiplier Achieves 95% Efficiency -  06/10/10 EDN Design Ideas:  Linear voltage regulators become inefficient when the input voltage is much higher than the regulated output.  The circuit in Figure 1 dramatically increases efficiency when the input voltage is more than twice the desired output; for example, using 12V to obtain a regulated 3.3 or 5VPDF contains multiple circuits scroll to find this circuit __ Circuit Design by Jeff Witt, Linear Technology Corp, Milpitas, CA

Switching (PWM) Solenoid Driver -  This is a very simple circuit to interface a current loop sensor to an input which is designed for a voltage, such as that from a standard potentiometer.  This page is technical so that interested persons can build the circuit themselves, but 4QD can also supply the interface on a 'postage stamp' sized (22mm x 27mm) board as shown in the first diagram.  it is a relatively trivial circuit!   __ Designed by Richard Torrens

Switching Current Pump Makes Better Charge -  01/16/97 EDN Design Ideas:  Many currently proposed battery-charger designs are simply voltage regulators redesigned to be current sources.  Unfortunately, this design approach is far from optimal because it leads to unnecessary hardware redundancy and complexity.  This type of charger also raises a stability problem because of the additional active device in the feedback loop __ Circuit Design by David Bell, Linear Technology App Note, Milpitas, CA

Switchmode Constant Current Source -  Operating a stepper motor using a fixed (constant) voltage supply results in poor torque at high speeds.  in fact, stepper motors tend to stall at fairly low speeds under such conditions.  Several approaches can be used to overcome this problem, one of which is to use a constant current supply in place of the more__ 

Switchmode converter 70W input:10-16VDC Output:200-300VDC -  Simple Switch mode up-converter is normaly called inverters.   input voltage 10-16 Volt, Output 200-300 Volt DC 70 W.  Uses UC1825 from Unitrode, and two iRF540 to drive the push-pull transformer. __ Designed by Thomas Scherrer OZ2CPU

Switchmode converter 800W & Audio Amp. -  The converter uses an UC1825 from Unitrode, this IC drives two HUGE and powerfull MOS-FETS iRFP150.  input voltage 11 to 16 volt, input current max load 70 A.  Output voltages +30 and -30 balanced __ Designed by Thomas Scherrer OZ2CPU

Switch-mode Power Supply for a Tube Car Amplifier -  To minimize heat loss on any transistor, I use two pass FETs.  in the car, input voltage is either 11.5-12.5V (engine off) or 13.5-14.5V (engine on).  in the first case, T1 and T2 are fully ON, no need for heatsink.  in the second case, T1 is OFF, T2 ON, all voltage and power excess __ Contact klausmobile @ yahoo.Com

Switch-mode supply draws 43-mW standby power -  EDN Design Ideas:  06/10/1999   Switch-mode offline supplies offer better efficiency than linear supplies.  However, the efficiency of a switchmode power supply (SMPS) seriously degrades with light loads, and commutation losses provoke power dissipation well above 1W even with no load.    __ Circuit Design by Christophe Basso and François Lhermite, Motorola SPS, Toulouse, France

Synchronized Regulator Produces Coherent Noise -  03/17/94 EDN Design Ideas:  By using a gated-oscillator architecture instead of a clocked-PWM one, gated-oscillator-type switching regulators permit high efficiency over extended ranges of output current.  This architecture eliminates the housekeeping currents associated with the continuous operation of fixed-frequency designs.  Gated-oscillator regulators simply self-clock at whatever frequency is necessary to maintain the output voltage.  Typically, loop-oscillation frequency ranges from a few hertz to the kilohertz region, depending on the load.    __ Circuit Design by Jim Williams, Sean Gold, and Steve Pietkiewicz, Linear Technology, Milpitas, CA

Synchronous Buck Produces Negative Voltage -  6-Mar-03 EDN Design Ideas:  Many electronic systems require both positive and negative voltages to operate properly.  Generating an efficient, low-voltage positive output from a higher voltage input typically entails the use of a synchronous buck regulator.  But when generating a negative output voltage from a positive input voltage, you'd typically use a flyback topology, especially at higher output currents __ Circuit Design by John Betten, Texas Instruments, Dallas, TX

Synchronous Buck/Boost High Power White LED Driver -  LT3453__ Linear Technology/Analog Devices

Synchronous flyback provides high-efficiency conversion -  07/22/04 EDN Design Ideas:  Buck regulators are usually the first choice when you design nonisolated step-down regulators unless the ratio of ViN to VOUT is greater than 10, the input voltage is high, or both.  Low duty cycle can be problematic for FET drivers and cause current-mode control loops to lose control.  Efficiency can fall dramatically to 60 to 70% at low VOUT and current of only a few amps __ Circuit Design by Wayne Rewinkel, National Semiconductor, Phoenix, AZ

Synchronous PolyPhase Boost Converter for Cool & Powerful Applications -  Boost power conversion is important function in many industrial, automotive and commercial applications.  Higher power level customers have to deal with issues of high ripple currents, high power dissipation and higher EMi levels.  Linear Technology’s LTC3788 breaks new ground in boost converter technology, achieving the__ Linear Technology/Analog Devices App Note, Goran Perica-Applications Engineering Section Leader Jun 11th 2010

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DC to DC:  #'s - A       B - D       E - L       M - R       S - Z


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