Question about combining VR1,VR2 and VR3 in HMC1060LP3

Hello,

My customer want to get 200mA of current rating through combining VR1, VR2 and VR3 pins.

(VR1 = 100mA, VR2 & VR3 = 50mA at 3.3V Default configuration.)

an they use a combining VR1, VR2 and VR3 pins of HMC1060 like VR2 and VR3 pins of HMC860 in attached schematic?

And if they can, would you advise how to combine VR pins in HMC1060?

 

 

 

 

Please advise me.

 

 

Regards,

Se-woong

hmc830lp6ge_eval_pcb_schematic1.pdf
  • 0
    •  Analog Employees 
    on Jun 23, 2015 5:45 PM over 5 years ago

    You can combine VR1/2/3 outputs on the HMC1060 but there are some caveats:

    • maximum total output current should be de-rated 5%.  For VR1/2/3 the maximum current will be 0.95(200mA)=190mA.
    • add small series resistors  with each output for load distribution.  Use 1 ohm for VR1 and 2 ohms for VR2 and VR3.  The output node is the common connection for all resistors.  There will be a small voltage drop across the series resistor.  The feedback filter capacitors should be connected directly between the VRx and RDx pins as on the eval board.
    • You must use the default output voltages (no voltage setting resistors).  Addition of external resistors to adjust the output voltage cause output voltage variations due to poor off-chip vs on-chip resistor matching.
    • You can only combine outputs from the same HMC1060 device