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The use of synchronous rectification on boost converter

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bhl777

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Hi All, I have a question regarding using synchrounous rectification on boost converters. On Buck coverter, we know that using synchrounous rectification helps the efficiency when we have low Vout and high load applications.
1. With regard to boost conveter, is there any specific adavatage or specific applications we want to use synchrouous boost converter?
2. In addition, if we already have a Schottky diode as the freewheeling diode (not the normal PN junction diode), what we usually need to take into consideration if we tried to replace the SBD with a MOSFET?
Thank you!
 

Hi,

1) the advantane is highe efficiency. But with higher output voltage the possible benefit in efficiency becomes lower.

2) all that's important for you: Besides Rds-on, switching speeds, specified currents an voltages...cost, availability, package...

You may use the Mosfet in reverse, so that - at light loads - you may switch OFF gate control... while the internal body diode does the job. Check if the internal body diode is fast enough. But I expect it's not a problem, because at light loads you will be in DCM.
The current should be zero befor the low side Moset gets switched ON.

Klaus
 
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    bhl777

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You have to take into consideration enough dead time between each Mosfet drive, to prevent cross-conduction.

Also, would you require the synchronus Mosfet to have a diode emulation mode?

Google the term.
 
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    bhl777

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