SN6505A: 12V/12V isolation power
Part Number: SN6505B
Is there a reference design for using the SN6505B to take 5V and turn it into 12V using a 5000Vrns transformer? Output Current from 12V will be 100mA but if the design supports more that would be acceptable to get the 5000Vrms rating on the transformer.
Is it better to use a 5 to (slightly above) 5V transformer paired with the voltage doubling circuit or size the transformer to do the 5 to 12V?
Hi Spencer,Thank you for posting, and welcome to E2E! A reference design for isolated push-pull power supplies can be found here (SLLA436).Although voltage-doubling configurations can be used to generate 5V to 12V isolated power supply rails with a wider selection of transformers, using transformers designed to output the required 12V is typically more efficient and requires less components; there aren't many other trade-offs between these two options.Below are a few transformers which can be used with SN6505B to generate an isolated 12V power supply from a 5V input supply and are specified for 5000Vrms isolation performance:
Efficiency varies with each transformer, but these components are all specified to handle >100mA outputs. Let us know if you'll be using a different one! We can analyze other transformers' specs and confirm expectations regarding compatibility.Thank you,Manuel Chavez
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In reply to Manuel Chavez:
Thanks Manuel, did I implement this correctly? My understanding is that this should generate roughly 15Vdc when 5Vdc is applied to VCC?
In reply to Spencer Miles86:
Hi Spencer,The transformers listed above intentionally supply >12V on the secondary side to both account for parasitics in the system, like diode voltage drops, and allow for the option of regulation devices (LDOs) to be used for a more consistent voltage output across loads and operating conditions.Respectfully,Manuel Chavez
As long as the circuit outputs 12.25V (after the diodes) then the converter will be able to regulate to 12V after.
I just wanted to make sure that this transformer will provide an output in the 12.25V - 20V range.
Spencer,The schematic you shared above is also implemented as expected in the typical configuration. Minor optional improvements can be made as follows:
If precisely 12V output is needed instead of 15V, an LDO can be added at node "+15V_EXT." The output voltage is expected to vary around 15V across load currents and operating conditions without one.Please let us know if you have additional questions.Best,Manuel Chavez
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