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LP8863-Q1: LP8863 low temperature -40 degree test issue

Part Number: LP8863-Q1

Hi Team

Currently doing a low temperature -40 degree test!
When LP8863 adjusts the brightness from high to low or from low to high, the switch block of 8863 will not work!
Later, we tested to adjust the input voltage to reciprocate from 9V to 16V under the same brightness state.
There is also a phenomenon that the boost is stopped

At present, there is BSTOVP in the error interruption , but will this part cause the entire shutdown?


LED's VF voltage 11V~14V
8863 voltage divider setting 24V
Using SEPIC topology

  • Hi, Kygo, 

    Yes, if the BSTOVP is happened, Boost circuit will stop working. Device goes to standby and waits until output
    voltage falls below threshold before restarting.

    Pls try increasing RB3 for a try. Like 600kohm etc.  

    Regards, 

    Xiaoguang 

  • Hi Xiaoguang

    將RB3 調整至600k後,做低溫-40度測試,

    LP8863 在調整亮度由高到低或是由低到高,依然會出現8863的switch區塊無法進行工作,目前量到的波形如下

    再麻煩您幫忙跟我說,還有哪些波形需要量測與確認?

    下方黃色波形是 ISNS pin 在進保護時量到的波形

    目前測試條件下:

    Vin :16V

    PIN14 : 平時都小於 200mV (目前RB6 & CB5都是拔掉)

    Vo:11V

    Io: 200mA

    Log 讀到128

  • Hi, Kygo, 

    Can you send me all the register data when fault happens? 

    Also, with INT pin trigger, to see below waveform with oscilloscope 

    (1). Vin, Vsen_N, SD

    (2). Cpump, VLDO, VDD

    (3). Switching node, GD, ISNS, Vout

    (4), Vout, LEDx

    Regards, 

    Xiaoguang