ZHCSGN5B March 2017 – July 2018 LP8863-Q1
PRODUCTION DATA.
During normal boost operation, boost voltage is raised if any of the LED outputs falls below the low headroom threshold level. Open LED fault is detected if boost output voltage has reached the maximum and at least one LED output is still below the threshold. The open string is then disconnected from the boost adaptive control loop and its output is disabled. Any LED fault sets the status bit LED_STATUS and an interrupt is generated unless LED interrupt is disabled. Reason for the open LED faults can be read from bits OPEN_LED and LEDx_FAULT (x = 0...5, indicating the faulty LED) in INTERRUPT_STATUS_2 register. These bits maintain their value until device power-down while the LED_STATUS bit is cleared by the interrupt clearing procedure. If a new LED fault is detected, LED_STATUS is set and an interrupt generated again.
Shorted LED fault is detected if one or more LED outputs are above the SHORTED_LED_THRESHOLD setting and at least one LED output is inside the normal operation widow (see Figure 26). Shorted string is disconnected from the boost adaptive control loop and the LED PWM output is disabled. LED_STATUS status bit is set and an interrupt generated similarly as in open LED case. Shorted LED fault reason can be read from bits SHORT_LED and LEDx_FAULT (x = 0...5, indicating the faulty LED) in INTERRUPT_STATUS_2 register.