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ISO3086T: Recommended output current

Youhei Miyaoka
Expert 4095 points
Part Number: ISO3086T

Hi team,

In datasheet 6.3 Recommended Operating Conditions, the output current is -60mA to 60mA.

Let me confirm output current. My customer think following condition;

Vcc: 5V

Vout: 2.3V

Load: 54Ohm

Iout = Vout/Load = 42.6mA

So, this is within recommended condition. Is this understanding correct?

Regards,

Youhei MIYAOKA

  • 0
    TI__Mastermind 29505 points

    Hello Miyaoka-san, 

    Yes, your understanding is correct. A 54Ohm load resistor will have a current that is within the recommended operating conditions. 

    Best,
    Andrew

  • 0 in reply to Andrew J
    TI__Expert 4095 points

    Hi Andrew,

    Thanks for your answer. In addition, my customer want to know situation of Iout=60mA.

    This value(60mA) is within expectations that the voltage rise higher than typical 2.3V or the bus resistance decrease than 54Ohm? Teach me the situation please.

    If so, does this mean that the bus voltage may rise to about 3.2V?

    Regards,

    Youhei MIYAOKA

  • 0 in reply to Youhei Miyaoka
    TI__Mastermind 29505 points

    Hello Miyaoka-san, 

    These are good questions. The VOD spec (2.3V) is characterized with a RL=54 Ohms at 27degC as designated in the highlighted section and test conditions of the datasheet below. 

    The minimum VOD value of 1.5V is tested across recommended operating conditions which implies the 60mA current. The typical application curves below show that at max data rate and RL = 54 ohms the current will be 60mA and the VOD will be 1.5V.

    Figure 6-3 also shows that with a proper load resistor, current will be between 50mA - 60mA. Using these numbers on figure 6-12 shows that at these load currents the VOD will stay between 2.5V - 1.5V for 5V operation.  

    I hope this helps. 
    Best,
    Andrew

  • 0 in reply to Andrew J
    TI__Expert 4095 points

    Hi Andrew,

    Thanks for clear answer. Let me quickly confirm, why increase supply current by signaling rate increase?

    Regards,

    Youhei MIYAOKA

  • 0 in reply to Youhei Miyaoka
    TI__Mastermind 29505 points

    Hi Miyaoka-san, 

    The output will begin to conduct and draw current when ISO3086T (or any digital device) drives the bus to a state. Therefore, more transitions will cause increased current draw and the supply current will increase as signal rate increases.

    Best,
    Andrew