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TPS61165 /Open LED Protection

Tsukui Yusuke
Guru 21930 points
Other Parts Discussed in Thread: TPS61165

Hi,

Could you tell me about TPS61165 open led protection.
Customer useing TPS61165 under the condition of PWM dimming.
In the case of PWM dimming operation, does it become 38V by Open LED protection?

There was a similar post.But there is no reply.
http://e2e.ti.com/support/power_management/led_driver/f/192/t/330267

Best Regards,
Yusuke/Japan Disty

  • 0
    Guru 21930 points
    Hi Team,
     
    Can I get the information ?
    If you need more information or if  I should  clarify my comment ,
    please let me know.
     
    Best Regards,
    Yusuke　/ Japan Disty
  • 0
    TI__Intellectual 1055 points

    Hello Yusuke-san,

    The open LED protection is the same for both dimming modes.  The voltage at the SW pin and FB pin are monitored during each switching cycle.  The device turns off the switch FET and shuts down the IC when both of the following conditions persist for 8 switching clock cycles: (1) the SW voltage exceeds the VOVP threshold and (2) the FB voltage is less than half of regulation voltage.  The output will then fall to input supply level and the device remains in shutdown until the CTRL pin is toggled. 


    Regards,

    Nisha

    Open
    LED
    protection
    circuitry
    prevents
    IC
    damage
    as
    the
    result
    of
    white
    LED
    disconnection.
    The
    TPS61165
    monitors
    the
    voltage
    at
    the
    SW
    pin
    and
    FB
    pin
    during
    each
    switching
    cycle.
    The
    circuitry
    turns
    off
    the
    switch
    FET
    and
    shuts
    down
    the
    IC
    when
    both
    of
    the
    following
    conditions
    persist
    for
    8
    switching
    clock
    cycles:
    (1)
    the
    SW
    voltage
    exceeds
    the
    V
    OVP
    threshold
    and
    (2)
    the
    FB
    voltage
    is
    less
    than
    half
    of
    regulation
    voltage.
    As
    a
    result,
    the
    output
    voltage
    falls
    to
    the
    level
    of
    the
    input
    supply.
    The
    device
    remains
    in
    shutdown
    mode
    until
    it
    is
    enabled
    by
    toggling
    the
    CTRL
    pin.
    The
    product
    of
    the
    number
    of
    external
    series
    LEDs
    and
    the
    maximum
    forward
    voltage
    of
    each
    LED
    plus
    the
    200-mV
    reference
    voltage
    does
    not
    exceed
    the
    38-V
    minimum
    OVP
    threshold
    or
    (N
    LEDS
    ×
    V
    LED(MAX)
    +
    200
    mV
    ≤
    38

    V