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ISO1212: Power isolation.

Prajwal Naik
Prodigy 50 points

Part Number: ISO1212
Other Parts Discussed in Thread: ISOM8110

Tool/software:

Hi,

Greetings of the day!!

Please suggest me a circuit for below specifications.

Input - 0 to 300V DC

Output - 0 to 300V DC

the circuit should isolate input and output ground (Input side GND and Output side GND must be different). 

later the output 300VDC must be down converted to 0 to 10V DC.

Thanks,

Prajwal

  • 0
    TI__Mastermind 34575 points

    Hello Prajwal, 

    Please see the datasheet section 9.2.1.2.4 Designing for Input Voltages Greater Than 60. In that section, there are links to App notes and threshold calculator to help you through the design process. Let me know if you have any questions. 

    In general, the below circuit will be used with an  Rshunt that should divide the input voltage down to below the 60V abs max. 

    Best,
    Andrew

  • 0 in reply to Andrew J
    Prodigy 50 points

    Hi Andrew,

    Thanks for your response. Could you please explain me in detail for the 300V case.

    Regards, 
    Prajwal

  • 0 in reply to Prajwal Naik
    Prodigy 50 points

    Also,

    The input 300 voltage keeps varying from range 300V to 0V, in that case will the ISO1212 gives the direct proportional output voltage?

    Example: 

    case 1 : Input 300V will the output also be 300V?

    case 2 : Input 290V will the output also be 290V?

    case 3 : Input 240V will the output also be 240V?

    Regards,

    Prajwal

  • 0 in reply to Prajwal Naik
    TI__Mastermind 34575 points

    Hello Prajwal, 

    Thank you for reaching out. ISO1212 takes digital inputs up to 60V (~24V typical) and outputs a 0-5V logic signal to a microcontroller. The input is not proportional to the output since it is a digital signal. The designs above allow the ISO1212 to detect higher voltages.  

    ISOM811x could be used to isolate the signal if the current can be limited to below 20mA. 

    However, based on your description I do not think either of these are options. Are you looking for an isolated power solution? 

    Best,
    Andrew

  • 0 in reply to Andrew J
    Prodigy 50 points

    Hi Andrew,

    Yes. 


    Power supply level conversion with isolation solution for voltage monitoring.

    Input 0 to 360V should get converted to 0 to 10V with separate grounds.

    Thank you.
    Prajwal

  • 0 in reply to Prajwal Naik
    TI__Mastermind 34575 points

    Prajwal, 

    To be clear, ISO1212 could work for line voltage detection. This would indicate if the input were ON or OFF. ISOM8110 would show a rough approximation of the DC input as an analog signal for voltage monitoring. However, neither device will convert power. 

    To use ISOM8110 an input resistor needs to be used. The resistor should be sized so that the highest voltage does not cause greater than 50mA (20mA is recommended) to pass through the diode input. 

    The output current will be proportional to the input (Ic = CTR * IF) and can be scaled to 0-10V as needed. 

    Best,
    Andrew