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MAX3232: MAX3232MPWREP

Pietro Zappia
Prodigy 80 points
Part Number: MAX3232

Hi Everybody,

it seems we are facing some radiation problems with that parts we use in EP grade. We inspect our PCBA with X-Ray since on the board we have three BGA components.

The transceiver is not directly exposed but it is located at around 1.5 cm from a BGA part. We calculated that it should receive a dose around 0.5Gray whic is very small but we see changes in the Voh, see the table:

temps (sec)

VOH measured

VOH datasheet

0

5537.305

5000

5

5480.394

5000

10

5443.978

5000

15

5419.664

5000

20

5390.538

5000

25

5366.335

5000

30

5335.208

5000

35

5294.539

5000

40

5267.659

5000

45

5240.418

5000

50

4985.032

5000

55

4874.149

5000

60

4729.827

5000

65

 

5000

70

 

5000

75

 

5000

80

4021.316

5000

85

 

5000

90

 

5000

95

 

5000

100

3179.852

5000

Coud you please tell me if you have a reference value of acceptable radiation that part can withstand? Which are most sensitive elements within that component?

Thank you by advance.

  • 0
    TI__Guru 62930 points
    Pietro,
    This device is not characterized for TID, so it is difficult to predict at what level will start showing issues.
    However, as you note 0.5Gray is a very small dose.
    So, I would not expect to see any performance shift from 50rad(Si) dose.
    Your table above shows temperature as well, but also indicates seconds. Can you describe this? Is this one unit with data taken up to 100c?

    Do you have VOH levels pre-exposure?

    Can you indicate the schematic of the output drivers? What loading?
    Regards,
    Wade
  • 0 in reply to Wade Vonbergen
    Prodigy 80 points

    Hi Dave,

    thank you fro your feedback.

    Values you see in the table are at ambient temperature.

    The VOH level before exposure is the one at time 0.

    Here an extract of the schematic attached. The measure is done on a not used line so no load charge and at input we have a pull-down of 10K ohm, measure done on TP51.

    Pietro

  • 0 in reply to Pietro Zappia
    TI__Guru 62930 points
    Pietro,
    I found a paper indicating that this device was tested to 8Krad without significant change in performance. So, I would not expect 50rad to even be detected. Either there is higher dose than you are estimating, or there is something else going on in the circuit.
    Can you operate without exposing to radiation source? Does behavior change?
    Has this been seen on multiple units?
    Are your capacitors polarized, and if so mounted in correct orientation? (Schematic does not show they are polarized).
    Do you see same degradation on pin 9, or is only on the RS232 side?
    Regards,
    Wade