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CSD16301Q2: How to understand direction of current in shunt switching ?

Yang zhang
Prodigy 110 points
Part Number: CSD16301Q2

Hi sirs,

 I am studying TOF circuit. In "OPT8241-CDK-EVM IB 10-50", I don't know U15/U16 working condition.

 I have read "sbaa209a.pdf". I want know these questions:

1.How does D11~16 work? Is U15 closed or open ?How does the peak current flow?

2.What 's the function of U16?

  • 0
    TI__Intellectual 1660 points

    Hi Yang,

    1. you can consider evrything to the left of laser+mosfet combination as a constant current source. This current is routed either between U15 or D11~D16 based on the TRIG_G signal state. U15 being an nmos, is turned on when TRIG_G is high causing the entire current to flow through U15. On the other hand, when TRIG_G is low, all the current flows through D11~D16.

    2.The above current flow is completed only when U16 is turned on ie when the the Illum_En_G signal is high. In the CDK, U16 is employed as an additional level of protection to ensure eye safety operation of the lasers. This also makes sure that lasers are turned on only during integration( when ILLUM_En_G is high) time.

    Regards

    Nithin