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[Ideas For Design]
Triple-Output DC-DC Converter Uses Ceramic Capacitors

Dongyan Zhou  |   ED Online ID #7877  |   April 26, 2004


Even the smallest modern electronics systems now require more than one power-supply voltage. The challenge is producing the required voltages in as little board space as possible. Designers can produce three output voltages using a single controller IC, thereby reducing the supply's overall cost and size.

Figure 1 shows a circuit that generates 1.2-, 3.3-, and 5-V outputs. U1 (LTC3727-1) is a two-phase, two-output synchronous step-down controller with an input voltage range of 4 to 36 V and an output range of 0.8 to 14 V. These specifications make it suitable for a wide variety of applications, from computers to automotive. This particular circuit takes advantage of ceramic input and output capacitors to minimize ripple, cost, and size.

The third output is created using a MOSFET and a transformer. Regulation of the 5-V third output isn't as tight as the other two outputs, but it's good enough for most applications. Figure 2 shows that load regulation for the 5-V output remains within a ±3% window over a wide range of output conditions. Figure 3 depicts the output ripple of each of the three supplies.

Because the controller IC has such a wide output range, the first output in Figure 1 can be modified to generate the 8-V supply commonly required by DVD players, digital tuners, and car-navigation systems. External components limit load currents, which can be adjusted for higher output currents if necessary.

This particular controller IC (U1) features a 20-µA shutdown current, which is important for increasing battery run time in applications that are idle for significant lengths of time.

For some applications, the operating frequency must be carefully selected to avoid certain problem frequencies. There are two ways to set the frequency over a 250- to 550-kHz range. A dc voltage from 0 to 2.4 V can be applied at the PLLFLTR to set the frequency, or the PLLIN pin can be synchronized to an external oscillator.


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    Reader Comments

    Schematic diagram of a dualoutput dc power supply output=+15V and -15V and -5V of not more than 15 components identify the different sub-sections that make up the power supply on the schematics and explanation on the operation of the power supply Thanks

    Anonymous -June 11, 2008

    hi any one please give me some overview about fpga and the procedure to use it

    smith -January 06, 2008

    hi need ur help for this.

    dual output dc power supply(output +15v and -15v) of not more than 15 components,scematic diagram and explaination how it works thanks alot

    Anonymous -December 28, 2007

    hi need ur help for this.

    dual output dc power supply(output +15v and -15v) of not more than 15 components,scematic diagram and explaination how it works thanks alot

    Anonymous -December 28, 2007

    can u teach us how to draw a -15v shematic diagram?

    Anonymous -June 25, 2007

    Using triple outpu dc power supply output=+15V and -15V and -5V of not more than 15 components identify the different sub-sections that make up the power supply on the schematics and explanation on the operation of the power supply

    Anonymous -June 23, 2007

    can anyone show mi the diagram of dual output DC supply +15V and -15V

    Anonymous -June 14, 2007   (Article Rating: )

    can anyone show mi the diagram of dual output DC supply +15V and -15V not more than 15 components

    Anonymous -June 14, 2007   (Article Rating: )

    hi i'm very interested for making projects plz send some resent circuits to my mail it's helpfull for me.

    keshav -March 08, 2007

    Using triple outpu dc power supply output=+15V and -15V and -5V of not more than 15 components identify the different sub-sections that make up the power supply on the schematics and explanation on the operation of the power supply

    Neo -December 20, 2006   (Article Rating: )

    Anyone knows how to generate, 3 outputs +12, -12, and +5V. Dc-DC conversion with an input of 48V. Please give me any suggestions.

    Anonymous -September 28, 2006

    Anyone knows how to generate, 3 outputs +12, -12, and +5V. Dc-DC conversion with an input of 48V. Please give me any suggestions.

    Anonymous -September 28, 2006

    send me an e-mail at plamen_petkov5@hotmail.com with your requirements. I can show you a simple way of deriving multiple output voltages from a single buck regulator. Depending on load requirements a second switcher may be used.

    Anonymous -January 26, 2006

    can show me a schematic diagram of a dual output dc power supply (+15V, -15V) with not more than 15 components?

    Anonymous -December 27, 2005   (Article Rating: )

    How can i make a LED flasher(white )with 4 LEDS?Input voltage is only 2.3 Volt

    Nikhi -November 24, 2005

    Can show me a schematic diagram for a triple output DC Power supply:(+15V,-15V,-5V) with not more than 15 components

    Anonymous -July 20, 2005   (Article Rating: )

    Can anyone show me a triple output Power Supply:

    Output: +15V -15V -5V with not more than 15 components

    Anonymous -July 20, 2005

    can you teach how to draw the triple-output diagram with less than 15 components and the output voltages is(+15v,-15v and +5v)?

    Anonymous -July 17, 2005   (Article Rating: )

    Can you teach how to draw the triple-output diagram with less than 15 components and the output voltages is (+15v,-15v and +5v)

    Anonymous -July 17, 2005   (Article Rating: )

    Can u make the triple-output diagram simpler??

    Anonymous -July 10, 2005
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