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How to generate isolated power for optocoupler or isolator in medical device circuit?

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sshk123

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Hello, I want to know how to isolate the power source.

Our device uses the internal battery source

question.png

In this figure, how to generate the VDD_iso?

The purpose is to pass the hipot test for medical device.

I found the isolated power generator ADuM5010 from 'Analog Device', but it consumes large power.
 

Hi,

I assume there are ready to buy DC/DC converters with medical approval.

Generally you need extended gap and creepage distance. Reduced leakage current, reduced capacitive coupling.
You could build it on your own by usung a small (but according regulations) small pulse or signal transformer.
(Optocoupler needs to be carefully chosen, too. And a carefully designed PCB layout)

For further help we need at least informations like voltage and current.

Klaus
 

You better to use low leakage current isolated DC to DC converters, While selecting the DC to DC converter you should be very careful about safety standards.

UL/cUL/IEC/EN 60950-1 Safety Approval,Medical Safety meets 2xMOOP per 3rd Edition of IEC/EN 60601-1 &ANSI/AAMI ES60601-1
 

Thank you for your fast, and kind reply.

Our system consumes under 10mA, battery voltage 3.7V, internal digital supply 1.8V, analog voltage 3.3V

I have two followed questions.

1. Where should I insert the isolator? between
1) AFD - ADC
2) ADC - MCU
3) MCU - Charger
4) Charger - Battery (if I use disposable battery, then LDO - Battery)

2. Is there any recommended IC for low power consumption? The ADuM5010 consumes 2~3mA current in steady state, but it is large portion in our system
 

Thank you for your quick and kind reply.

Since our application is low power consumption within 10mW, I want to use low-power DC/DC Converter.

Our regulation is 1kV DC in 1 minute, or 1.414kV 60Hz AC in 1 minute (CB 3.1 edition)

Would you please recommend some IC for this application? or what parameter should I carefully consider in DC/DC converter selection?
 

Hi,

1. Where should I insert the isolator?
Click to expand...
I see only one option: Exactely where the optocoupler is.
In your picture the yellow part is the isolation. And the DCDC converter needs to cross this .

Klaus
 

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