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Power Supplies:  DC to DC / Switch Mode and DC to DC Converters
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Last Updated: November 30, 2017 10:28 AM

Circuits Designed by Dave Johnson, P.E. :

 Caps Provide Voltage Boost to Series Regulator - This circuit adds some capacitors and diodes to a traditional transformer type series regulator circuit to extend the normal operating range.  It can insure regulation during low line voltage conditions or it can squeeze a few more watts out of a plug-in-the-wall power adapter power supply. . . Circuit by David Johnson P.E.-January, 1998

 Charge Pump Battery Charger-+5 Volts - The circuit below will trickle charge a four cell pack of AA or AAA NiMH
batteries.  The circuit draws current from the +5v available a USB connection and pumps about 70ma of current into the battery.  This should be enough current to fully charge a pack of . . . Hobby Circuit designed by Dave Johnson P.E.-February, 2010

 Charge Pump Efficiently Divides Supply Voltage  - This circuit uses a few FETs and logic devices to down convert a DC voltage to about one half its value. . . Circuit by Dave Johnson P.E.-July, 2000

 Classic Linear 5v Supply using 6.3vAC Transformer - A classic method for producing a regulated +5v DC supply is shown below.  This circuit consists of an iron core transformer, a bridge rectifier, a filter capacitor and a voltage regulator.  Many people are tempted to use a very popular 6.3v transformer. . . Circuit by David Johnson P.E.-February, 2009

 CMOS Inverter 125khz LC Oscillator - This circuit uses a single CMOS inverter to form a series resonant LC oscillator.  The values shown set the oscillation at about 125KHz but the other frequencies are possible by changing the main LC values. . . Circuit by Dave Johnson P.E.-March, 2002

 CMOS Inverter forms a Resonant LD Oscillator  - This circuit uses a single CMOS inverter to form a series resonant LC oscillator.  The values shown set the oscillation at about 125KHz but the other frequencies are possible by changing the main LC values . . . Hobby Circuit designed by Dave Johnson P.E.-March, 2002

 CMOS Inverters Form 125Khz Oscillator - This circuit inverts the LC components so the inductor is grounded.  Two inverters are needed to produce the needed oscillation.  Again, the values shown set the frequency at 125KHz but can be changed to produce other frequencies . . . Hobby Circuit designed by David A. Johnson P.E.-March, 2002

 CMOS Nand Gate Forms Gated 125Khz Oscillator - This circuit is uses a NAND gate as an inverter.  The gate allows the oscillator to be gated on and off.  Again, the values shown set the frequency at 125KHz but can be changed to produce other frequencies. . . Circuit by David A. Johnson P.E.-March, 2002


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

Circuit Provides +5 Volt Gate Bias from  48 Volt Input -  App Note #1803__ Maxim Integrated

Circuit Provides 1.5V, 7A Bus Termination -  EDN Design Ideas:  09/14/95    Some of the newest high-performance processors require a 1.5V bus terminator that can source currents as high as 7A.  This terminator requires a very fast transient response, because the device must react to high peak-current changes that have extremely fast rise times.  The 1.5V terminator circuit in Fig 1 meets these demanding requirements. __ Circuit Design by Chester Simpson and Mineo Yamatake, National Semiconductor, Santa Clara, CA

Circuit provides 5V gate bias from 48V -  09/19/02 EDN Design Ideas:  A small and simple circuit derives 5V from the -48V rail that telecomm applications typically use (Figure 1).  Useful for gate bias and other purposes, the 5V supply delivers as much as 5-mA output current.  A shunt reference __ Circuit Design by William Hadden

Circuit Provides Leading-Edge Blanking -  29-May-03 EDN Design Ideas:  in isolated switch-mode power supplies using peak-current-mode control, generally the current-sense resistor senses the current on the primary side of the power converter.  Figure 1 shows a typical circuit, in which R2 is the current-sense resistor that monitors the current.  The current-sense signal goes to the input of the PWM comparatorin this case, the PWM comparator's input (iSENS __ Circuit Design by Michael O'Loughlin, Texas Instruments, Dallas, TX

Circuit Provides Universal AC-Input-Voltage Adapter -  08/25/11  EDN Design Ideas:  Use a TRIAC and optocoupler to automatically change between doubler and bridge configurations.  he input-rectifier stage of an offline power supply converts an ac-line voltage to a dc voltage, which powers a dc/dc converter.  if you configure the rectifier section as a full-wave bridge for a universal mains input of 92 to 276V rms and 47 to 63 Hz, you must design the dc/dc converter to operate over a wide range of input voltages.  This approach increases the cost of components and reduces the efficiency of the dc/dc converter.   __ Circuit Design by JB Castro-Miguens, Cesinel, Madrid, Spain, and C Castro-Miguens, University of Vigo, Vigo, Spain

Circuit reduces negative-voltage stresses on control IC -  04/18/02 EDN Design Ideas:  in a synchronous, buck switching power supply, the two FETS and the output inductor meet at the phase node (Figure 1).  The phase node often connects directly to the control iC.  The voltage on this node swings from the input voltage to some voltage lower than ground.  if the voltage goes too far below ground, the ESD structures or other circuitry within the control IC can become forward-bia __ Circuit Design by Michael Day, Texas Instruments Inc, Dallas, TX

Circuit replaces & Improves on Power Modules at Less Than Half the Price -  DN347 Design Notes__ Linear Technology/Analog Devices

Circuit translates I2C voltages -  12/26/02 EDN Design Ideas:  This design idea explores level-shifting an iC bus from 5V/ground (positive domain] to ground/25V (negative domain].  in multisupply systems, you sometimes face a situation in which digital information stored in logic circuits running from 5V to ground needs conversion to analog signals referenced to a negative supply __ Circuit Design by Peter Liu, Optron X, Allentown, PA

Circuit Variations Produce Negative Voltages -  09/01/00 EDN Design Ideas:  This circuits easily configures basic switched-capacitor converters to also do some negative conversions.  Basic switched-capacitor converters generally provide one simple conversion.  They commonly double, usually invert, and sometimes halve a positive input voltage.  Because they are not regulated converters and do __ Circuit Design by Clinton Jensen, National Semiconductor Corp, Santa Clara, CA

Classic Linear 5v Supply using 6.3vAC Transformer -  A classic method for producing a regulated +5v DC supply is shown below.  This circuit consists of an iron core transformer, a bridge rectifier, a filter capacitor and a voltage regulator.  Many people are tempted to use a very popular 6.3v transformer. . . Circuit by David Johnson P.E.-February, 2009

Clean Switcher Powers 16 Bit A/D Converters -  07/07/94 EDN Design Ideas:  The low-noise switcher in Fig 1 works much like a TV's horizontal-deflection circuit to provide clean power for a 16-bit A/D converter.  in operation, Q3 is a logic-level gate-drive MOSFET driven by the same 100-kHz square wave that clocks the A/D converter.  When Q3 turns off, the primary of T1 resonates with C3 and flies back to 25V.  Energy __ Circuit Design by Patrick Kevin Garner, Advanced Technology Systems, McLean, VA

CMOS Inverter 125khz LC Oscillator -  This circuit uses a single CMOS inverter to form a series resonant LC oscillator.  The values shown set the oscillation at about 125KHz but the other frequencies are possible by changing the main LC values. . . Circuit by Dave Johnson P.E.-March, 2002

CMOS Inverter forms a Resonant LD Oscillator  -  This circuit uses a single CMOS inverter to form a series resonant LC oscillator.  The values shown set the oscillation at about 125KHz but the other frequencies are possible by changing the main LC values . . . Hobby Circuit designed by Dave Johnson P.E.-March, 2002

CMOS Inverters Form 125Khz Oscillator -  This circuit inverts the LC components so the inductor is grounded.  Two inverters are needed to produce the needed oscillation.  Again, the values shown set the frequency at 125KHz but can be changed to produce other frequencies . . . Hobby Circuit designed by David A. Johnson P.E.-March, 2002

CMOS Nand Gate Forms Gated 125Khz Oscillator -  This circuit is uses a NAND gate as an inverter.  The gate allows the oscillator to be gated on and off.  Again, the values shown set the frequency at 125KHz but can be changed to produce other frequencies. . . Circuit by David A. Johnson P.E.-March, 2002

Coilless step-up converter yields dual outputs -  09/01/97 EDN Design Ideas:  Rapidly proliferating battery-powered systems create a need for dc/dc converters that can accommodate a wide input-supply range.  Depending on the battery-pack configuration, the input-supply voltage may be higher or lower than the desired regulated output voltage.  The circuit in Figure 1 provide as regulated 5 and 3V supplies from a wide input range without the need for inductors.    __ Circuit Design by Sam Nork, Linear Technology Corp, Burlington, MA

Common Mode filter inductor analysis -  Coilcraft RF Magnetics App Note- __ Designed by Coilcraft Power Magnetics Application Note

Compact Inductorless Boost Regulates White LED Bias Current -  App Note #1116__ Maxim Integrated

Compact Step-Up Converter Conserves Battery Power -  DN358 Design Notes __ Linear Technology/Analog Devices

Comparator adds current limit to V2 controller -  05/21/98 EDN Design Ideas:  (FILE
has several  circuits, scroll down) Many step-down controllers satisfy the need for generating low voltages for Ps and logic.  The lower the output voltage, the greater the importance of building a system with fast transient response.  Some new controllers use the V2 control architecture, which provide as several speed improvements over. __ Circuit Design by Dimitry Goder, Switch Power Inc, Campbell, CA

Comparator Improves Regulator's Efficiency -  04/28/94 EDN Design Ideas:  The UC384X family of current-mode PWM regulators requires a current shunt or some other component to develop a voltage proportional to the output current.  This shunt must develop a 1V signal at full load.  For off-line supplies, the 1V requirement is not hard to meet because of the high voltage on the supply's dc bus.  However, if you want __ Circuit Design by Cristophe Basso, European Synchrotron Radiation Facility, Grenoble, France

Complementary-PaIR DC/DC Converter Simultaneously Doubles, Inverts Supply Voltage -  EDN-Design ideas -- 06/20/12   Change a single positive supply into twice its positive and equal negative voltages.   __ Circuit Design by Ajoy Raman

Compressor-Mate -  protection for refrigerators, freezers and air conditioners  __ Designed by Tony van Roon  VA3AVR

Configure buck converter for boost operation -  12/17/98 EDN Design Ideas:  (File contains many circuits.  Scroll to find this one.)  __ Circuit Design by Mehrzad Koohian, Semtech Corp, Newbury Park, CA

Constant Current Battery Charger -  A simple method of charging a battery from a higher voltage battery is shown in the circuit below to the left.  Only one resistor is needed to set the desired charging current and is calculated by dividing the difference in battery voltages by the charge current.  So, for example if 4 high capacity (4000 mA hour) ni-cads are to be charged at 300 mA from a 12 volt battery, the resistor need,  __ Designed by Bill Bowden

Constant-Current DC/DC LED Driver in ThinSOT -  LT1932__ Linear Technology/Analog Devices

Constant-on-time buck-boost regulator converts a positive input to a negative output -  7-Dec-04 EDN Design Ideas:  Buck regulators find wide application as step-down regulators for converting large positive input voltages into a smaller positive output voltages.  Figure 1 shows a simplified buck regulator that operates in continuous-conduction modethat is, the inductor current always remains positive.  The output voltage, VOUT, is equal to DViN, where D is the duty-cycle ratio of the buck switc __ Circuit Design by Robert Bell, National Semiconductor Inc, Chandler, AZ

Controller IC & one-shot form resonant controller -  11/28/02 EDN Design Ideas:  Resonant power supplies are popular because of high efficiency, low noise, and compactness.  You can implement a resonant buck or boost converter using a single switch.  The regulation of the output in such a converter derives from using a constant on or off time and a variable frequency.  The UC1864 controller IC (Texas instruments, www __ Circuit Design by C Rajan, Centre for Advanced Technology, Indore, India

Controlling a Variable Voltage Power Supply using the DS1809 Pushbutton Control -  App Note #1035__ Maxim Integrated

Convert 5V to 10V -  05/26/05  EDN Design Ideas:  witched-capacitor circuit doubles, inverts dc source __ Circuit Design by Ken Yang, Maxim Integrated Products Inc, Sunnyvale, CA

Converter Generates 3.3V from Two or Three Cell -  11/21/96  EDN Design Ideas:  Generating 3.3V from two or three cells poses a design challenge.  The regulator must step down the voltage when the cells are fresh but step up the voltage when the cells are semidischarged and weak.  One solution to this problem is a flyback-transformer __ Circuit Design by Robert Badalian, Maxim Integrated Products, Sunnyvale, CA

Converter Has High Efficiency At Low Load -  01/06/94 EDN Design Ideas:  The high overhead of most DC/DC converters' normal supply currents do not permit high efficiency at low load currents.  The micropower components and Circuit design of the converter in Fig 1, however, enable it to maintain 90% efficiency for load currents below 8 mA __ Circuit Design by Dana W Davis, Maxim Integrated Products, San Jose, CA

Critical-mode control stabilizes switch-mode power supplies -  04/23/98 EDN Design Ideas:  Discontinuous-conduction-mode operation eases switch-mode power-supply design and allows for better response to step-load changes.  Operating at the critical-conduction point--beginning a new cycle at the exact point the inductor current falls to zero--ensures that the converter stays in discontinuous-conduction mode. __ Circuit Design by Christophe Basso, Motorola Semiconductors

Ck converter yields 90% efficiency -  EDN-Design ideas-- 09/01/94    The simple DC/DC converter in Fig 1 has an efficiency of 90% min and output ripple measured at 10 mV p-p.  This circuit employs an inexpensive 78L15 regulator in an unusual manner.  The regulator, iC2, operates as a voltage-level shifter.  Because the regulator's normal output is tied to ground, the regulator tries to maintain its input at its characteristic 15V above its voltage-reference (VR) pin's level by drawing the appropriate current through biasing resistor R1.   __ Circuit Design by Peter Demchenko, VN, Vilnius, Lithuania

Ck Converter Yields 90% Efficiency -  09/01/94 EDN Design Ideas:  The simple DC/DC converter in Fig 1 has an efficiency of 90% min and output ripple measured at 10 mV p-p.  This circuit employs an inexpensive 78L15 regulator in an unusual manner.  The regulator, iC2, operates as a voltage-level shifter.  Because the regulator's normal output is tied to ground, the regulator tries to maintain its input at its characteristic 15V above its voltage-reference (VR]pin's level by drawing the appropriate current through biasing resistor R1.  You can use this trick with any member of the 78LXX family __ Circuit Design by Peter Demchenko, VN, Vilnius, Lithuania

Current Limit Protects Power Bus -  12/12/97 EDN Design Ideas:  Protects a power bus from a load short within a guaranteed2 sec response Time __ Circuit Design by Ron Lenk, Temic/Siliconix, Santa Clara, CA

Current Limiting Bench Power Supply -  This is a 1-amp variable-voltage PSU.  it adjusts from about 3v to 24v: and has the added feature that you can limit the maximum output current.  This is invaluable when (for example) you power-up a.   __ Designed by Ron J.

Current-Limited DC/DC Converter Simplifies USB Power Supplies -  DN252 Design Notes__ Linear Technology/Analog Devices

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