Output Power Usage of ADuM3070


As mentioned in the datasheet of ADuM3070, we can get up to 2.5W output power with 5V input voltage. I  wonder up to what percentage of this output power can be occupied by the transformer. I mean, I'm plannig to use schematic in Figure 32 given in the datasheet and  a transformer having power rating lets say, 2.3W (instead of 2W) for Viso(+24V). On the other hand we have Vdd2(+5V) as an output voltage of ADuM3070. Is that possible? Its not briefly mentioned in the datasheet.

Thank you in advance!

  • ozgun:

    In answer to some of your questions:

    1. For figure 32 schematic, the doubling circuit spec table 4 limits the 5V to 15V output current to 100mA min, 140mA typ or 1.5W to 2.1W.  If you try to go beyond this amount of output power, the 1.3A peak limit described in the Application Information section of the datasheet, the Power Considerations states that the pulse by pulse current limit on the primary side limits the peak current through the switches to 1.3A peak, which will limit the power that can be delivered.

    2. The ADuM3070 Table 4 limits the VDD2 5V output to 50mA load, only 250mW output and 500mW max on the internal regulator at 15V If Vreg = VISO = 24V the power in the internal LDO would need to be limited to 500mW max or about 26mA at 24V output, for an output of only 130mW max.  You would need another scheme to get your output power.

    Regards, Brian

  • Brian, thank you for the reply.

    Could you recommend any other reference schematic to obtain more than 2.1W output power then? 

    Regards, Ozgun

  • Ozgun:

    From one of your EngZone posts, attached is the block diagram - is this still the application you need? I have placed the supply current values on the diagram, and if 80% efficiency the ADuM3070 VISO 5V supply would need to output 375mA, which meets the min spec for the ADuM3070 of 400mA at 5V.  

    Is this the application you need and if so what is the need for more than 2.1W?

    Regards, Brian

  • Ozgun: Attached is the block diagram - Is this the application you need and if so what is the need for more than 2.1W?

    Regards, Brian

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