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Original question:

AM26LV32E: Datasheet revision change(D -> E)

AM26LV32E: When FAB (DLN) is replaced with FAB (RFAB), the waveform becomes distorted.

R.Fukunaga
Genius 3125 points

Part Number: AM26LV32E

Hi all,

Even though the peripheral circuit has not been changed, the waveform is distorted simply by replacing the existing FAB (DLN) with FAB (RFAB).

Send the equivalent circuit, propagation delay, and oscilloscope waveform.

image.png

 

Left: DLN, Right: RFAB
CH1:IN+
CH2:IN-
CH3: A (line receiver non-inverting input)
CH4: B (line receiver inverting input)

image.png

If the signal delay is a problem, I think it is related to the change of capacitance component.

There is Cpd Power dissipation capacitance One channel 150 pF (typ).

image.png
1) Is there any difference in Cpd before and after the process? How much difference is there?
2) When the resistance values between Vcc-A/B-GND were measured, the results were different as shown below.

No. Measure
Point		 Value of resistor
DLN RFAB
1 Vcc-A 222k 130k
2 B-GND 222k 130k
3 A-GND 888k 141k
4 Vcc-B 546k 142k

Is the measurement result of RFAB reasonable?
If the characteristics of RFAB are reasonable, how wide is the variation of the resistance value?

Best Regards,

Ryusuke

  • 0
    Genius 3125 points

    Hi all,

    How is your progress?

    I look forward to your reply.

    Best Regards,

    Ryusuke

  • 0
    TI__Guru* 81381 points

    Hi Ryusuke,

    Sorry for the delay.

    R.Fukunaga said:

    Left: DLN, Right: RFAB
    CH1:IN+
    CH2:IN-
    CH3: A (line receiver non-inverting input)
    CH4: B (line receiver inverting input)

    image.png

    E2e site isn't letting me zoom in to get a closer look.

    Can you put the scopeshots in a powerpoint and reupload back on e2e?

    R.Fukunaga said:
    1) Is there any difference in Cpd before and after the process? How much difference is there?

    We don't actually measure this spec if it's not actually called out in the datasheet.

    Cpd isn't a measured spec but an assumed value. This spec is usually paired with a power rating. This is likely a copy paste line item from a different datasheet since their is no power rating calculation provided in the datasheet. 

    R.Fukunaga said:

    2) When the resistance values between Vcc-A/B-GND were measured, the results were different as shown below.

    No. Measure
    Point    		 Value of resistor
    DLN RFAB
    1 Vcc-A 222k 130k
    2 B-GND 222k 130k
    3 A-GND 888k 141k
    4 Vcc-B 546k 142k

    Is the measurement result of RFAB reasonable?
    If the characteristics of RFAB are reasonable, how wide is the variation of the resistance value?

    We don't characterize the impedance of the pins for our devices. It basically moves with the voltage that the DMM uses to measure it. DMM's with higher voltage will cause higher leakage current due to the ESD cells and give a lower value which can vary. I did do this sort of measurement before and found that when I used a handheld DMM I found the readings were larger than when I used a benchtop source meter DMM which gave me values similar to yours. 

    Your findings of different impedance values is what we've seen other customer's report when they run ICT and see fail failures.

    -Bobby