U22 LM issues,

Discussion in 'DM800HD Schematic drawings, Pcb images etc..' started by Johnny B., Jun 11, 2015.

  1. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    7 pins version,

    2740.jpg

    5 pins lm, two versions, one always gives out 5v,
    the second has only 5v out during startup.

    LM-5p-onbyboot.jpg

    Note, the LM 5 pins (LM2596) is only active when the pin 5 (on / off) 0 to max 1.6v dc has.
    At a higher voltage the LM is not active.
    If the pin is not connected, usually with a cap to ground.
    Then the LM is always active.
    LM 7 pins (LM2599),
    When the SD /SS pin 7 voltage is between 0V and 1.3V, the regulator is in shutdown, the output voltage is zero.
    With the SD /SS pin 7 voltage between approximately 1.3V and 1.8V,
    the internal regulator circuitry is operating.
    When the SD /SS pin 7 voltage is between 1.8V and 2.8V, the regulator is in a Soft-start condition.
    Note: LM2599S-5.0, If you disable pin 7 from the motherboard it become active.
    When active the voltage are,
    Pin,
    1-12v
    2-5v
    3-5v
    4-0v (Ground)
    5-1.7v
    6-5v
    7-between 5/7v