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DS90UB960-Q1: POC design

Paddy Chao
Prodigy 220 points
Part Number: DS90UB960-Q1

Hi

We observed the ds90ub960-q1 EVM is using LDO to supply power to camera module.

Consider high power consumption of camera module and high power loss of LDO while dropout voltage is high.

Is it able to use buck-boost to replace LDO?

Any recommended part number?

  • 0
    TI__Guru** 103215 points

    Hello Paddy,

    Yes, the LDO can be replaced by a switcher device to provide PoC if needed, but extra care should be taken in the design process for the switcher/PoC circuit to ensure that noise reaching the FPD-Link receiver/transmitter pins is minimized as it can degrade SNR if switcher ripple or transient response are poor. 

    Usually we recommend an LDO whenever possible to improve the noise performance and we recommend increasing the PoC voltage as high as possible to reduce the current requirement which also helps ensure that the PoC passive components - particularly ferrite beads operate in a region where they provide high impedance to the high speed signals on the link. 

    For recommendations on an ultra-low noise switcher solution, please post an inquiry in the forum section for DC/DC devices. PoC noise requirements are listed in the 960 datasheet - refer to page 150 where the PoC noise at the deserializer side (at the deserializer's RIN+/- pins) should be < 10mVpp

    Best Regards,

    Casey  

  • 0 in reply to Casey McCrea
    Prodigy 220 points

    Hi Casey

    Thank you for information. Would like to know

    (1) The VPOC should be prior to POC filter circuit as shown in figure 36 of datasheet, right?

    (2) The VPOC <10mV requirement is on-load or off-load?

    (3) I saw other requirements from application note as below. What's difference between below requirement and  VPOC <10mV requirement?

    Vpoc supply noise ≤ 100mVpp

    Vpoc pulse ≤ 500mVpp @ camera frame rate frequency

    Vpoc pulse slew rate ≥ 100 us/V

    BR

    Paddy

  • 0 in reply to Paddy Chao
    TI__Mastermind 18755 points

    Hi Paddy,

    (1) Are you able to clarify this question for me?  Also what figure are you referring to in the datasheet? I see figure 36 is referring to the I2C bus.

    (2) Is this the requirement on the side of the deserializer which is different the the requirement on the serializer side of the link which is addressed below.

    (3) Below is a image showing a typical PoC voltage and noise.  Vpoc supply noise refers to the noise introduced from the supply.  Vpoc pulse refers to the transient introduced from the sensor's change in current draw during capture valid frame data and blanking periods.  The slew rate refers to the length of time it takes for the voltage to change.

    Regards,

    Nick