P2 Eval Board Owners, I need your help!

245

Comments

  • All in the 4megohm range
  • jmgjmg Posts: 13,915
    cgracey wrote: »
    So, it looks, so far, like we don't have any ohmic connections between the VIOs and GNDs on any of the first-silicon chips.
    This suggests that something was just screwy in this last silicon run. The only change to the pad ring was the PLL filter settings, which wouldn't have had such effects, and only connects to V2431, anyway.
    I've not seen any lateral current measurements yet ? (Shows in the waveforms above, and I measure ~10mA here )
    Done with VDD powered and measure the current from V2431 to GND, all other VIOs isolated
    Did you simulate to find where that flows thru ?
  • Terrel at Parallax did a bunch of measurements on the seven remaining glob tops we have.

    He found one VIO pin on one device which had a 190-ohm path to GND. See page two of attachment.

    He read ~8M-ohms on every pin, except the bad one. These pins were single and not grouped in sets of two, like on the P2 Eval.

    We ought to be able to initially screen the bad dies on the wafer prober by measuring resistance between VIO (all grouped) and GND (all grouped) and looking for >100k ohms to pass the die. That would keep the ball rolling, while ON Semi figures out what happened.

  • cgracey wrote: »
    P2 Eval Board Owners, I need your help!
    **snip**
    I would think the negative meter probe would go to GND (any of those four GND posts) and the positive meter probe would go to the Vxxxx pin header pin being measured. You'll need to measure with the VIO pin being subjected to the positive voltage. Otherwise, you may wind up measuring the clamp diode to GND, which we don't care about.

    If you could report your measurements as such, it would be most helpful:

    V0007 = 4.7M ohms
    V0815 = 4.7M ohms
    V1623 = 4.7M
    V2431 = OPEN ohms
    V3239 = 4.6M ohms
    V4047 = 4.6M ohms
    V4855 = 4.6M ohms
    V5663 = OPEN ohms

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  • jmgjmg Posts: 13,915
    cgracey wrote: »
    Terrel at Parallax did a bunch of measurements on the seven remaining glob tops we have.

    He found one VIO pin on one device which had a 190-ohm path to GND. See page two of attachment.

    He read ~8M-ohms on every pin, except the bad one. These pins were single and not grouped in sets of two, like on the P2 Eval.

    Can you mount those and check they work ok.
    Even the 190 ohms indicates ~ 17mA if that is purely resistive and does not degrade further.
    cgracey wrote: »
    We ought to be able to initially screen the bad dies on the wafer prober by measuring resistance between VIO (all grouped) and GND (all grouped) and looking for >100k ohms to pass the die. That would keep the ball rolling, while ON Semi figures out what happened.
    Are they confident the (possibly damaged) probes are not damaging die ? ;)
    I'm surprised they do not have a 'soft start' approach, that injects some low mA, and checks the pins are above some test level. Effectively a resistance to gnd test.
    Curious what yields do they get ? (ignoring the peak drain issue)

    Any chance this could be ESD related ? What ESD tests did OnSemi do on ES1 and ES2 ?

    It just seems unlikely that a PAD metal part of the die could be erratically variable. Generally the clearances there, are much less tight than the die core, and photo imaging is usually very stable.

    Did they have any issues on other companies dies, in the same shuttle run ? (tho they might not admit to that...)
  • The P2-V1 readings I got using a TENMA 72-10405 meter

    V0007 = 6 M ohms
    V0815 = 9 M ohms
    V1623 = 8 M ohms
    V2431 = 8 M ohms
    V3239 = 14 M ohms
    V4047 = 9 M ohms
    V4855 = 8 M ohms
    V5663 = 8 M ohms
  • V0007 = 21.81 ohms
    V0815 = 20.66 ohms
    V1623 = 7.54ohms
    V2431 = 2.37ohms
    V3239 = 9.47 ohms
    V4047 = 12.21 ohms
    V4855 = 11.51 ohms
    V5663 = 10.47 ohms

    With my meter leads shorted together I get .047 ohms
  • jmgjmg Posts: 13,915
    V0007 = 21.81 ohms
    V0815 = 20.66 ohms
    V1623 = 7.54ohms
    V2431 = 2.37ohms
    V3239 = 9.47 ohms
    V4047 = 12.21 ohms
    V4855 = 11.51 ohms
    V5663 = 10.47 ohms

    With my meter leads shorted together I get .047 ohms
    Those seem all very low ? Is there a missing 'M' ? Does the P2 work ?

  • evanhevanh Posts: 7,875
    edited 2019-08-15 - 22:25:40
    VonSzarvas wrote: »
    Is anyone else getting "open diode" when measuring those pins with diode multimeter setting? I found that on 2 of the VIO-to-GND pairs. Rest were close to either 1V or 2V.

    Edit: Scratch that. Might be the pin fet reacting to measurement voltages.

    Yes, first and last.

    EDIT: Ha! You're right, testing those all again today and the results are mostly 4+ volts all around.

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  • Fluke 87 used - they are all 5-10 MOhms depending on how long I want to wait for those bypass caps to charge.
    The difference between theory and practice is that, in theory, there is no difference between theory and practice, but in practice, there is.
  • @jmg

    Those seem all very low ? Is there a missing 'M' ? Does the P2 work ?

    There is no missing M

    I am using a EEV blog 121 GW multimeter

    Does the P2 work ?

    I can't say because I haven't been using it yet. I've been too busy lately but I just dusted it off last weekend and had a look at the accessory boards. I am hoping to free up some time this weekend or next to run a few programs.
  • Hi Bob Lawrence

    Looks like you did found something new ....

    You are the first one reporting such low resistance values.

    Since you've never powered-up your Eval board, perhaps it's advisable not doing so for a while, before giving Chip a chance to express any ideas he can have about it.

    Only a thought

    Henrique
  • jmgjmg Posts: 13,915
    @jmg

    Those seem all very low ? Is there a missing 'M' ? Does the P2 work ?


    There is no missing M I am using a EEV blog 121 GW multimeter
    Were those with the VIO jumpers removed, to isolate the VIO pins ?
    Does the P2 work ?
    I can't say because I haven't been using it yet. I've been too busy lately but I just dusted it off last weekend and had a look at the accessory boards. I am hoping to free up some time this weekend or next to run a few programs.

    Is it easy to plug it in, to quickly check if you get 3.3V and 1.8V and the chip is not hot ?

  • @jmg

    re:Is it easy to plug it in, to quickly check if you get 3.3V and 1.8V and the chip is not hot ?


    I plugged it in and the 1.9 VDC and the 3.3VDC voltages are fine. The chip feels cool after about 10 minutes. There is no apparent short.
  • jmgjmg Posts: 13,915
    @jmg
    re:Is it easy to plug it in, to quickly check if you get 3.3V and 1.8V and the chip is not hot ?
    I plugged it in and the 1.9 VDC and the 3.3VDC voltages are fine. The chip feels cool after about 10 minutes. There is no apparent short.

    Good, seems those ohms readings might be bogus then... an average of say 15 ohms, would be 0.726W, which would be warm...

  • V0007 = 14.0 Mohms
    V0815 = 14.0 Mohms
    V1623 = 14.0 Mohms
    V2431 = 14.0 Mohms
    V3239 = 14.0 Mohms
    V4047 = 14.0 Mohms
    V4855 = 14.1 Mohms
    V5663 = 13.3 Mohms
  • MJBMJB Posts: 1,119
    V0007 = 21.81 ohms
    V0815 = 20.66 ohms
    V1623 = 7.54ohms
    V2431 = 2.37ohms
    V3239 = 9.47 ohms
    V4047 = 12.21 ohms
    V4855 = 11.51 ohms
    V5663 = 10.47 ohms

    With my meter leads shorted together I get .047 ohms

    did you try reversing the measurement leads to reverse polarity?
  • Thats interesting. Are you able to measure the open circuit voltage of that eevblog 121 GW, Bob?

    Just put the 121 GW into resistance measuring mode, and measure its open circuit DC voltage using a second voltmeter. I think values that small would indicate its a relatively high voltage that its measuring with
  • samuellsamuell Posts: 405
    edited 2019-08-16 - 00:26:08
    @jmg

    Those seem all very low ? Is there a missing 'M' ? Does the P2 work ?

    There is no missing M

    I am using a EEV blog 121 GW multimeter

    Does the P2 work ?

    I can't say because I haven't been using it yet. I've been too busy lately but I just dusted it off last weekend and had a look at the accessory boards. I am hoping to free up some time this weekend or next to run a few programs.
    Hi Bob,

    I would be cautious about that EEV Blog multimeter. Try to measure with another multimeter. Also, make sure that the 121GW multimeter does not output more than 3.3V when measuring resistance (you can measure the voltage the 121GW outputs with another multimeter, with the probes in the air, and then with the probes measuring on the circuit). I suspect that it is doing so, because that multimeter is powered by four AA cells in series, totaling 6V!

    Kind regards, Samuel Lourenço
  • jmgjmg Posts: 13,915
    samuell wrote: »
    I would be cautious about that EEV Blog multimeter. Try to measure with another multimeter. Also, make sure that the 121GW multimeter does not output more than 3.3V when measuring resistance (you can measure the voltage the 121GW outputs with another multimeter, with the probes in the air, and then with the probes measuring on the circuit). I suspect that it is doing so, because that multimeter is powered by four AA cells in series, totaling 6V!
    If you are unsure about the ohms readings, (CAPS can confuse some), you can try a simple 100R~1K series resistor power, and measure the pin voltage in voltage mode. (or drop over resistor)

  • @ jmg

    Were those with the VIO jumpers removed, to isolate the VIO pins ?

    No the VIO jumpers were on for the measurements

    @Tubular

    re:Are you able to measure the open circuit voltage of that eevblog 121 GW, Bob?

    Yes,

    .222 volts DC

  • Old Radio Shack 22-179A

    0007 = 2.624 M
    0815 = 2.971 M
    1623 = 3.449 M
    2431 = OL (Meter shows OL at > 3.999 M)
    3239 = 3.331 M
    4047 = 2.769 M
    4855 = 2.233 M
    5663 = 2.593 M

    C.W.
  • Late to the party:

    V0007 = 6.72 Mohms
    V0815 = 6.72 Mohms
    V1623 = 6.75 Mohms
    V2431 = 6.73 Mohms
    V3239 = 6.76 Mohms
    V4047 = 6.76 Mohms
    V4855 = 6.75 Mohms
    V5663 = 5.25 Mohms

    Amprobe 37XR-A
    garryj
  • Thanks, Everyone.

    It looks pretty certain that this VIO short to GND is only in the new silicon.

    It's not on every die, though. So, we should be able to screen away the bad ones with a resistance test on the wafer prober. Then, we can still get some initial chips packaged.
  • jmgjmg Posts: 13,915
    cgracey wrote: »
    .. So, we should be able to screen away the bad ones with a resistance test on the wafer prober. Then, we can still get some initial chips packaged.

    Can that probe test report the actual pin(s), and the current or resistance seen, when it tests ?
    That would help isolate the offending pins, if some never fail, vs some often fail, you can compare the clearances / metal etc

  • samuellsamuell Posts: 405
    edited 2019-08-16 - 01:45:40
    @ jmg

    Were those with the VIO jumpers removed, to isolate the VIO pins ?

    No the VIO jumpers were on for the measurements
    ...
    You are measuring the "output resistance" of either the LDOs, or the DC-DC converter, depending on your jumpers configuration. You should remove them, definitely.
    cgracey wrote: »
    Thanks, Everyone.

    It looks pretty certain that this VIO short to GND is only in the new silicon.

    It's not on every die, though. So, we should be able to screen away the bad ones with a resistance test on the wafer prober. Then, we can still get some initial chips packaged.
    Hi Chip,

    It is good to know that not all dies are defective. What would be the yield, by the way?

    Kind regards, Samuel Lourenço
  • If it is not on every die does that basically suggest this is only a manufacturing/yield issue as opposed to a design change issue? Or could there still be some possible offending design change that is somehow marginal affecting some chips and not others? Seems very weird that a design change would do that, one might imagine it would more likely to be a more consistent issue over all chips and less random if that were the case. Also is the probe tip burnout and this issue directly related? Did these high currents on VIO do the initial damage to those probe tips? Or, could a partially damaged probe tip have caused these low resistance paths to start to appear on subsequently tested chips, by somehow frying something internally due to arcing etc? Pure speculation and I don't know their test methodologies.
  • To add what rogloh said - When I was in big corporate defense industry as a design engineer - We always had GS - Golden Samples. These were usually sub-assemblies or final products that were more perfect than perfect: dimensionally, electrically and functionally. Problem in the field or on the production floor, we tested the offending product / component against the Golden Sample to quickly isolate the problem. Was it a manufacturing defect, contamination, assembly, electrical - whatever. We assumed nothing, but many times it was human error, or test fixtures themselves that caused most of the problems.
  • PropGuy2 wrote: »
    To add what rogloh said - When I was in big corporate defense industry as a design engineer - We always had GS - Golden Samples. These were usually sub-assemblies or final products that were more perfect than perfect: dimensionally, electrically and functionally. Problem in the field or on the production floor, we tested the offending product / component against the Golden Sample to quickly isolate the problem. Was it a manufacturing defect, contamination, assembly, electrical - whatever. We assumed nothing, but many times it was human error, or test fixtures themselves that caused most of the problems.
    It is common practice in the industry to have golden samples. But that is justifiable in bleeding edge processes where the lithography can fail, or samples can be slower than normal. Actually, this often happens in the same waffer, where you can have SS graded samples, and FF samples, and the in-between.

    However, I think this is a completely different case, where process just got botched. Mind that this is a 180nm process, and this should never happen. Anyway, correct me if I'm wrong.

    Kind regards, Samuel Lourenço
  • Cluso99Cluso99 Posts: 15,398
    edited 2019-08-16 - 16:42:10
    Golden Samples where i have used them are for the finished product (packaged pcb in case if relevant) as signed off by the customer.
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