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Use of ADuM6211 and ADM3101E

Question asked by Terumasa on Apr 17, 2015
Latest reply on Apr 20, 2015 by Terumasa

Hello

 

We would like to know that a current from Viso of ADuM6211 meets VDD2 of ADuM6211 and VCC of ADM3101E.

We will use thme at below condition.

Please let me know your advice.

 

Condition

ADuM6211: ( 3.3V supply at primary and sencondary)

Viso of ADuM6211 is connected to VDD2 and ADuM6211 and VCC of ADM3101E.

ADuM3101E(3.3V supply from Viso of ADuM6211)

 

We think below from description of datasheet.

Is it correct ?

 

VDD2 of ADuM6211

power supply current : 2.3 mA  Max

VCC of ADM3101E

power supply current : 7mA Max

 

So needed current is 2.3+7=9.3mA

Current from Viso of ADuM6211 is 20mA max at VDDp 77mA.

So current from Viso of ADuM6211 meets VDD2 of ADuM6211 and VCC of ADM3101E.

But, current needed by load capacitance is described in ADM3101E datahseet rev.C P.6 Figure 9.

So if load capacitance is over about  800pF  ( we think about 11mA at 800pF from Figure9)

the current from Viso can not meet VDD2 of ADuM6211 and VCC of ADM3101E.

Generally, 20feet of cable length is 1000pF.

So the cable lenght which we can use 16 feet max ( 20feet * 800pf/1000pf = 16 feet).

 

If there is any wrong with our understanding, please let me know it.

 

Regards,

Teruamsa

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