ADUM3070 Schematic Review

Hello Team;

Could you kindly help on the ADUM3070 Schematic Review; please?

Input: 5V; output : current 0.3A, voltage 5V,

My question:

1. For ISO-5V output; the VDD2 and Vreg should be connected together to the 5V_ISO; correct?

2. other component value are properly selected in the design?

Many thanks;

Bell

Parents
  • 0
    •  Analog Employees 
    on May 21, 2019 1:47 PM

    Re-posted the schematic:

  • 0
    •  Analog Employees 
    on May 21, 2019 3:55 PM in reply to Bellye

    Bellye: My answers to your requests:
    1. Yes, we recommend that you connect VDD2 and Vreg for VISO = 5V.

    2. The schematic review:

    Recommend 0.1uF for C574, 577, do not need C576.

    Recommend the use of transformer with equivalent specs to those listed in the datasheet. TR3,.has a primary inductance pins 1-3 of only 73uH, but the datasheet recommends 60 to 100uH minimum for each winding, which is pins 1-2 or 2-3. For pins 1-3 this would require 4 times the 60 to 100uH minimum for each winding, which is pins 1-2 or 2-3, for a value between pins 1-3 of 240 to 400uH.

    The part number for L8 is not shown, it is recommended for your 0.3A application to use a 47uH inductor with equivalent specs for 0.4 to 0.5A forward current and to not saturate.

    Regards, Brian

  • 0
    •  Analog Employees 
    on May 23, 2019 6:42 AM in reply to ADIApproved

    Hi Bkennedy;

    For the transformer pri inductance value from 240~400uH; is it a hard requirement? Or we can adjust it based on the application scenarios. 

    For this circuit with max 0.3A output current, the peak inductor current is around 0.3 + V/L*Ton = 0.3+0.2= 0.5A. while the selected transformer saturation current is 0.9A and ADUM3070 internal cycle by cycle current limit is 1.3A. Thus; would this transformer be OK for this application?

    Look forward to your advice. Many thanks!

Reply
  • 0
    •  Analog Employees 
    on May 23, 2019 6:42 AM in reply to ADIApproved

    Hi Bkennedy;

    For the transformer pri inductance value from 240~400uH; is it a hard requirement? Or we can adjust it based on the application scenarios. 

    For this circuit with max 0.3A output current, the peak inductor current is around 0.3 + V/L*Ton = 0.3+0.2= 0.5A. while the selected transformer saturation current is 0.9A and ADUM3070 internal cycle by cycle current limit is 1.3A. Thus; would this transformer be OK for this application?

    Look forward to your advice. Many thanks!

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