Hello.
On our display adapter board we are using LP8860 to drive backlight leds.
I have eeprom configured according to datasheed of LP8860 and our LCD:
- 3 strings
- 80mA via LED_CURRENT_CTRL and DRV_LED_CURRENT_SCALE
- 27V via BOOST_INITIAL_VOLTAGE
But I am unable to lit the backilgt.
In status registers I have this:
staus = 0x08
fault = 0x20
LCD fault = 0x00
It seems that PL_FET_FAULT is active.
But we have another display (another LCD, 4 strings, 36V and LP8860 configured for this conditions) and it's backlight works normal with PL_FET_FAULT active. Thus I can't figure out is PL_FET_FAULT a reason for the backlight not working.
In addition I tried turn on adaptive boost (by EN_ADAP) -- still no luck, but LED Fault indicate that all three strings are in open condition.
EEPROM configuration:
<register id="00" value="0xEF"/>
<register id="01" value="0xFF"/>
<register id="02" value="0x90"/>
<register id="03" value="0xA2"/>
<register id="04" value="0xD7"/>
<register id="05" value="0x01"/>
<register id="06" value="0xF2"/>
<register id="07" value="0x77"/>
<register id="08" value="0x77"/>
<register id="09" value="0x71"/>
<register id="10" value="0x7F"/>
<register id="11" value="0x00"/>
<register id="12" value="0x00"/>
<register id="13" value="0x30"/>
<register id="14" value="0xBA"/>
<register id="15" value="0x80"/>
<register id="16" value="0x83"/>
<register id="17" value="0x67"/>
<register id="18" value="0xC0"/>
<register id="19" value="0x16"/>
<register id="20" value="0x05"/>
<register id="21" value="0x86"/>
<register id="22" value="0xD2"/>
<register id="23" value="0xFF"/>
<register id="24" value="0x3E"/>
Here is our schematic:
Here is LCD backlight documentation:
