SN6501: Transformer Bridge Rectifier Without Center-Tapped Secondary Performs Voltage Doubling

Part Number: SN6501

Hi there,

I am using SN6501DBVR with transformer (turns ratio 1:1.3) and Bridge Rectifier Without Center-Tapped as shown below. Transformer parameter is also given. Without no load, I am getting 9.59V at output. With gradual increase in load from 3mA to 9mA, output reduces from 9.59V to 5.288V. Is there anything wrong in the design, also efficiency curve for such configuration is not mentioned in the datasheet. Can I get that information?

Thanks in advance & Regards,

  • Hi Prafulla,

    Thank you for posting to E2E and sharing your schematic as well as transformer parameters. It is expected for output voltages to be above the estimated value for 0mA and low loads and to decrease as load currents increase due to parasitics. One way to increase efficiency directly and thus, output voltage, is to use Schottky diodes on the secondary side with low forward voltage (Vf) ratings. Which diodes are currently used in your system?

    The transformer shown was not designed to work with SN6501. Although it should be compatible, its efficiency might not be optimal, and we do not have measurements with this part in either the typical or voltage-doubling configurations. Is it possible for you to test this circuit using a similar transformer like 760390014 or EPC3807G-LF?


    Respectfully,
    Manuel Chavez

  • Hi Manual,

    Thanks for your revert. Do you have any simulation file for such type of configuration? Also, is there any way by which I can find out relation between convertor efficiency with center tap & full bridge type of configuration?

    Regards,

    Prafulla S.

  • Hi Prafulla,

    You're welcome! My apologies, but we do not have simulation files available for this configuration. Please let me know the diode part numbers that are being used in this system and if it is possible to test this circuit using a different transformer part number to help determine whether the output voltage is appropriate for the mentioned load conditions.

    An estimate of efficiency can be made mathematically through the equation:

    efficiency (%) = Pout / Pin = (Vout x Iout) / (Vin x Iin)

    Please also share these calculations for 3mA and 9mA conditions when possible.


    Thank you,
    Manuel Chavez

  • Hi Prafulla,

    The equation above can be used to compare measured efficiency of both topologies, and the full-bridge topology will yield a slightly lower value due to parasitics of the added diodes in the full bridge.


    Thank you,
    Manuel Chavez

  • Hi Prafulla,

    Please share the information requested above if possible. If not, the efficiency is expected to be slightly lower for full-bridge topologies than for typical SN650x configurations, and measured efficiency can be calculated using the equation:

    efficiency (%) = Pout / Pin = (Vout x Iout) / (Vin x Iin)

    Feel free to reply to this post to continue the conversation or you may ask a new/related discussion using the red and yellow buttons in the upper right corner of this window.


    Thank you,
    Manuel Chavez