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LMH6525: Datasheet question especially AVDD/VDD/AGND/GND

Hironori Yoshimura
Intellectual 1840 points
Part Number: LMH6525

Q1 Page#9-10 Detailed block diagram.
 
I would like to know the part where the power supply is separated.
Please let me know each blocks are belong to?
VDDA, GNDA....
VDD, GND...

If possible copy block diagram and Add circle or mark for VDDA,GNDA related ?

Q2 Page#13 Fig-12

Vsupply = VDD or VDDA which one?


Q3 Page#18  Fig-16 heat skinking layout example.
 
Datasheet mention that unused pins should be connected isolated exposed thermal pad.
If customer connect to GND, Do you think any future risks are exisits or not?

Q4 Page#24

Exposed thermal pad should be connect to GND or AGND or No connections any others ? please advice me?


my customer's background: utilize more than 100pcsper board by 8layer PCB board.
Now my Customer would like to apply common GND which connects both AGND and GND
instead of datasheet shows separate method between AGND and GND.
My experience is that we can utilize common GND in internal PCB layer due to space limited.
But please let us know if you have found new concerns or others your thought?

Best Regards,
Hironori Yoshimura

  • 0
    TI__Genius 15555 points

    Hello Hironori,

    1) VDDA & GNDA correspond to the RF oscillator within the device.  This supply is associated with the amplitude & frequency biasing of the oscillator. 

    2) Vsupply as shown in figure 12 will correspond to VDD.

    3) Which pins are you referring to exactly? It seems datasheet mentions connecting unused pins to pad as a way of additional thermal relief, not doing this shouldn't cause any major issues as long as the device doesn't exceed it's thermal limitations.

    4) Yes not only can you use a common GND for both AGND and GND, but the same supply can be used for VDD and AVDD.

    Best,

    Hasan Babiker