ADL5611 Inrush current ?

I'm using ADL5611 powered by dropping resistor, the power is 8 Vdc and dropping resistor is 32 Ohm,  to obtain 5Vdc at pin 3 of  ADL5611 at 94mA of absorption. The ADL5611 device does not start well. To pin 3 (RF out) the voltage is 3.1 Vdc and the device absorbing 153mA, and remains in this state. The voltage of 8Vdc is generated by a linear voltage regulator that limits output start-up current at 1 A. The ADL5611 how much current is required to turn on properly?

  • 0
    •  Analog Employees 
    on Jan 7, 2014 12:35 AM

    Is the regulator driving any other devices or components that might be limiting the supply to the ADL5611? Does the setup deploy adequate decoupling and bypassing components as recommended in the datasheet?

  • I'm sorry for the delay, due to the failure to my pc.

    I tried the device on two separate printed circuit boards.

    The regulator is  LT1763 only for one ADL5611.

    The device is employed with the decoupling capacitance on power supply trace, as close as possible on power suppy inductor ... as EVB of ADL5611 .

    The device observed to 8Ghz not self oscillate.

    NOTE : If using tweezers momentarily touch the metal pin 1 input dell'ADL5611 the device comes out of this anomalous condition: Pin 3 rise from 3.1 Vdc to 5 Vdc immediately. (If before I touch the pin 3 of the ADL5611 I do not get the same effect : the voltage remains stably without uncertainty at 3.1 Vdc)

    Due to urgent work currently 'm using ADL5545 instead dell'ADL5611 . ADL5545 and works well on the same printed circuit board where it was mounted ADL5611 .

    Thanks for the reply , I look forward any information to verify the stability of my implementation.

    Best Regards

  • 0
    •  Analog Employees 
    on Jan 15, 2014 12:58 AM

    Do you have a capacitor at the output of the regulator? If so, what's the value of that capacitor?

  • On the output and input of the regulator there are two 10uF capacity.

    The large capacity are 10uF.

    Capacitor on pin 6 of the LT1763 is 10nF. The three capacity close to the 90.9 ohm resistors are 1nF, 100nF and 100pF.

  • 0
    •  Analog Employees 
    on Jan 21, 2014 1:00 AM

    Can you provide a simplified schematic listing components connected to the ADL5611? The setup is not completely clear from these pictures.

    One possible reason for the startup issue could be the timing characteristic introduced by the RC network at the output port of the amplifier (pin 3) The time constant introduced by the RC network would be approximately 10uF*32ohms (RC). The LT 1763 indicates that the regulator is stable with a 3.3uF output capacitor. Have you tried to reduce the output capacitance? The datasheet for the regulator also indicates that it can be setup to provide a fixed output voltage of 5V? Is that an option, and have you tried it?