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DS90UB953A-Q1: Temperature specifications

Sivaraj T
Prodigy 190 points

Part Number: DS90UB953A-Q1
Other Parts Discussed in Thread: DS90UB953-Q1

Hi,

We have designed a board using DS90UB953-Q1 Serializer. Due to the availability issues, we are planning to use DS90UB953A-Q1 for our current production.

We have compared both the datasheets to find the differences. There does not seem to be any major differences except the below new specifications given in DS90UB953A-Q1 datasheet under recommended operating conditions.

We could not understand clearly about what is specified here. Can you please clarify?

As per the description, We think it specifies the temperature range between which the PLL of the IC stays locked.

i.e, If the device powers ON or resets and PLL calibration is done at -10degC, it will stay locked as long as it operates between -30degC and -10degC. If the ambient changes to above -10degC, the PLL lock will fail and device operation will be failed. Can you please confirm if this is the meaning of the above specifications?

Thanks,

Sivaraj

  • 0
    TI__Mastermind 30680 points

    Hello Sivaraj,

    The only difference between the UB953 and UB953A devices is that the UB953A is designed to support an ambient temperature up to 125 degC (AEC-Q100 Grade 1), but the UB953 is designed to support an ambient temperature up to 105 degC (AEC-Q100 Grade 2).

    The UB953A has a greater range of ambient operating temperature (-40 degC to 125 degC).

    Best,

    Justin Phan

  • 0 in reply to Justin Phan
    Prodigy 190 points

    Hi Justin,

    Thanks for the reply. We understand that UB953A supports operating temperature of -40 degC to 125 degC.

    We have noted the below additional specifications in UB953A datasheet under recommended operating conditions.

    We could not understand clearly about what is specified here. Can you please clarify?

    As per the description, We think it specifies the temperature range between which the PLL of the IC stays locked.

    i.e, If the device powers ON or resets and PLL calibration is done at -10degC, it will stay locked as long as it operates between -30degC and -10degC. If the ambient changes to above -10degC, the PLL lock will fail and device operation will be failed.

    Can you please confirm if this is the meaning of the above specifications?

    Regards,

    Sivaraj

  • 0 in reply to Sivaraj T
    TI__Mastermind 30680 points

    Hi Sivaraj,

    The table describes how if the UB953 devices are at a certain temperature at power-up or PDB reset, there may be issues if the temperature falls (ramps down) below a certain point. But there will be no issues if the temperature rises (ramps up) to the specified 125 degC after power-up.

    If the temperature at power-up is between 45 degC to 125 degC, the temperature can ramp down to 25 degC with no issue. And it can ramp up to 125 degC with no issue.

    If the temperature at power-up is between -20 degC to 45 degC, the temperature can only ramp down 20 degC from its starting point, before unLOCK issues occur. But it can still ramp up to 125 degC with no issue.

    In your example, if Ts = -10 degC at power-up or PDB reset, then the temperature can fall to -30 deg C with no issues and the temperature can rise to the specified 125 degC with no issues.

    Best,

    Justin Phan

  • 0 in reply to Justin Phan
    Prodigy 190 points

    Hi Justin,

    Thanks for explaining in detail. 

    1. We understood from the Maximum value of Ts in the table, the device will unLOCK if the temperature ramps up above the starting temperature.

    So as per your explanation, the Maximum value in the table seem to be misleading. Please confirm.

    2. We could find this PLL lock temperature specifications only in the UB953A datasheet. This specifications are not provided in the UB953 datasheet. Can you please confirm if this PLL lock behavior over temperature will be same for UB953 and UB953A?

    Thanks,

    Sivaraj

  • 0 in reply to Sivaraj T
    TI__Mastermind 30680 points

    Hi Sivaraj,

    1. Here is my explanation. Depending on the starting temperature, the device may risk unLOCKing if the temperature ramps down (falls) below a certain level (according to the table entries). The device has no issue with ramp up (rising temperatures) to the max specified limit (125 deg C), regardless of the starting temperature.
      1. And just to clarify, this specification describes a worst case device.
      2. In most cases, the device will ramp across the entire temperature range with no issues.
    2. This table entry was only added to the UB953A datasheet because it only came up during our evaluation of the UB953A. We needed to perform additional validation on the UB953A because of its extended temperature range.
      1. This limitation has not been seen in the UB953 device and should not apply, but additional validation needs to be performed by out TI team before we can draw a conclusive answer.

    Best,

    Justin Phan