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TPS7A8300: Designing with TPS7A8300RGRR

Part Number: TPS7A8300
Other Parts Discussed in Thread: TPS7A94, TPS7A30, TPS7A33

Hello Team,
We are planning to use the regulator TPS7A8300RGRR in one of our applications.
The input is a 5.5V from a buck converter (LMR51450SDRRR).
The TPS7A8300RGRR is used to generate a voltage of 5V at 300mA current.
The 5V thus generated is used to bias a photodiode. 
So the voltage generated from the 5V LDO must be of very low noise and almost no ripple (Clean voltage).
Can you please comment on the selection of the IC TPS7A8300RGRR?

Also, we need a -5V rail which is very low noise and almost no ripple (Clean voltage).
Can you please suggest an LDO?
The input of the negative LDO will be from TPS63700DRCR.

Looking for your reply.

  • Hi Vijay,

    The TPS7A8300RGRR is one of the better LDOs on the market but there are better devices to use here.  I would consider the TPS7A94 which is the lowest noise LDO on the market (it has 46% lower noise than the next best LDO on the market).  It also has very high PSRR.  The intent of the TPS7A94 is to clean up a noisy input supply like a buck converter and provide an ultra low noise output to a noise sensitive load. 

    For the negative rail I would suggest either the TPS7A33 or TPS7A30.

    If you need even lower noise than what these LDOs provide by themselves, you can parallel them to lower the output noise.  Each LDO looks like an uncorrelated noise source to the next parallel LDO.  Uncorrelated noise sources in parallel reduce by the square root of the number in parallel.  So 2 parallel LDOs will have √2 reduction in noise, 4 parallel LDOs will have √4 = 2 reduction in noise, etc.  We have released new resources to help you with this and to make the design process very fast if you decide to parallel LDOs in your design - see the links below.

    PARALLEL-LDO-CALC

    Parallel LDO Architecture Design Using Ballast Resistors

    Comprehensive Analysis and Universal Equations for Parallel LDO's Using Ballast Resistors

    Thanks,

    Stephen