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Datasheet ADN8810 clarification

I need to make a laser driver that can give current output from 0 mA to 250 mA. I checked ADN8810 datasheet and found the recommended circuit with 2 resistors (Rsn) which are having value written over them as 1.6V (instead of ohm/kohm). Is this a typo?

Also I need to ask whether the recommended circuit shown is to get 300mA only or the circuit connection stays the same for smaller current values as well?

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  • Dear Rohan,

     

    ADN8810 is target to work with a laser diode, with about a threshold voltage: 1.6 ~ 1.8V. Please refer to datasheet Fig.1.

     

    In your prototype design, you have used one 1kohm resistor to replace the laser diode. At about Iout = 30uA,

    You could only generate 30mV, plus the voltage drop on Rsn, the resulted Vout voltage is still far below from the min. required Vcomp: 2.0V.  This might be the root cause why you failed to make ADN8810 works.

     

    Please replace the 1kohm resistor with one diode load (with a proper threshold voltage) hooked up as Fig.1 recommended, you would see a working ADN8810.

     

    Best Regards,

     

    Dongfeng

  • Hello Dongfeng:

    I tried using your email but it seems it doesn't work so I'll message you here.

    Based from your reply, you mentioned Iout = 30uA. Obviously this wouldn't fulfill the required Vcomp of 2V. But if Rohan chooses, Iout = 2mA, it should fulfill the minimum Vcomp of 2V. Will his circuit now work? I interpret this failure-or-not-failure situation as dependent on how much Iout you program ADN8810 to output.

    Anyway another question. If I will not use SB and RESET, do I just NIC them? connect them to ground? PVDD?

    Thanks

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  • Hello Dongfeng:

    I tried using your email but it seems it doesn't work so I'll message you here.

    Based from your reply, you mentioned Iout = 30uA. Obviously this wouldn't fulfill the required Vcomp of 2V. But if Rohan chooses, Iout = 2mA, it should fulfill the minimum Vcomp of 2V. Will his circuit now work? I interpret this failure-or-not-failure situation as dependent on how much Iout you program ADN8810 to output.

    Anyway another question. If I will not use SB and RESET, do I just NIC them? connect them to ground? PVDD?

    Thanks

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