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LM3492HC: LED open circuit detection function for LM3492HC

Caspar Chen21
Prodigy 30 points
Part Number: LM3492HC
Other Parts Discussed in Thread: LM3492

Hi TI Support team,

The LM3492HC provides thermal protection, over-power protection and limit output voltage. This over-power protection feature avoids damaging the current regulator owing to the shorting of many LEDs in one string.

However, I didn't see any feature about LED open circuit detection, so does this chip not support this function? Does TI have other external chips that can support this function?

BR,

Caspar

  • 0
    TI__Mastermind 28655 points

    Hello Caspar,

    LED open circuit will create a fault:

    "8.3.9.3 Output Current Undervoltage Indication
    The LM3492/-Q1 device gives an IOUTn (n = 1, 2) undervoltage indication if the voltage of the IOUTn pin when
    DIMn is high is lower than its minimum required voltage which can regulate ILED, and the voltage of the CDHC
    pin reaches its maximum. These conditions remain while the device applies 508 consecutive dimming signals on
    the DIMn pin. This means that the current of the LED string n does not reach the regulation value. In most cases,
    the IOUT undervoltage indication can be regarded as an open fault of the LED string n. A bit pattern (see
    Table 1) can be read from the COMM pin. The device does not latch off and continues to operate in the
    presence of the IOUT undervoltage indication."

    The maximum output voltage is set by the two feedback resistors when Vfb reaches 2.5V.

    Is this what you are asking about?

    Best Regards,