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For Partners Asking About the Backlight Driver Working System on iPhone6, Maybe this can help step measurement multitester

There are 4 Drawings of the Series and 1 List of Voltage values ​​to be checked to confirm the BackLight LED LCD problem

CASE ANALYSIS LED LCM / LCD iPhone 6:

To analyze the case of LED LCM in all types of iPhone there are several series / group units / modules that we must check that is:

I. BACKLIGHT DRIVER UNIT

iPhone6 ​​is classified this Group U1502 Unit
U1502 an IC LM3534TMX-A1 type BGA
with Pin Numbering Variable
Letter A, B, C, D and Figures 1,2,3
So the Number of BGA Feet is 4 x 3 = 12 feet BGA

Where to work this U1502 must be fulfilled all requirement requirement, Namely:

1. Input Analog Voltage:
   PP_VCC_MAIN via parallel C1552 and parallel C1597 enter at foot C3 U1502 as IN

2. Ground: Leg B3 U1502

3. Input Digital Voltage: PP1V8 that comes in the foot of C1 with the name VIO_SPI

4. Input Voltage Command: PP1V8_SDRAM that enter at foot B1 with name of HWEN (Hardware Enable)

5. Control SoC / CPU / AP:

• AP_BI_I2C0_SDA (Application Processor_Bidirect_I2C0_SerialDATA) on A1 U1502
• AP_TO_I2C0_SCL (Application Processor_Ke_I2C0_SerialCLOCK) * Introduction to data in A2 U1502

5.a. Internal Chipset Backlight Driver The BUS controller consists of 2 Paths

• AP_TO_PMU_AND_BL_DWI_CLK at foot B2 U1502 under SCK name
• AP_TO_PMU_AND_BL_DWI_DO at foot C2 U1502 with SDI Name

1. Input Volt Via Inductor L1503: Go to A3 U1502 with name SW (Switch Mode)

2. Output Protection: in Leg D1 U1502 with OVP Name (Over Voltage Protection)

3. Feed Back VLEDCATODE / VLED-:

• PP_LCM_BL_CAT1
  (PositivePower_LiquidCrystalModule_Cathode1) at the foot of D3 U1502
• PP_LCM_BL_CAT2
  (PositivePower_LiquidCrystalModule_Cathode2) on Foot D2 U1502

1. Output BACKLIGHT DRIVER Protected:

• PP_LCM_BL_ANODE
  (PositivePower_LiquidCrystalModule_BackLight_Anode) which will enter J2019 Connector LCM B2B (Board to Board) via FL2024 first becomes PP_LCM_BL_ANODE_CONN

Line PP_LCM_BL_ANODE_CONN can be measured in C2017 then enter into J2019 Connector LCM B2B at foot no 2
then go into the LCD / LED LCD and out the current through the Path at the foot J2019 no 4 PP_LCM_BL_CAT1_CONN and feet J2019 no 1 under the name PP_LCM_BL_CAT2_CONN
which will lead to U1502 at the foot of D3 and D2

II. How the BACKLIGHT DRIVER Module Works on iPhone6

1. Input Analog Voltage (PP_VCC_MAIN) is the required voltage for U1502 to enable U1502 to be on / on
   of course one package with groundnya (Pasutri ... hahaha)

2. Input of Analog Voltage / PP_VCC_MAIN also through L1503 15UH-20% -0.72A-0.9OHM will be induced so that the output voltage variable becomes larger.
   But the voltage variables are REGULATED by SW (Switch Mode) based on the command of HWEN (Hardware Enable) through the input voltage PP1V8_SDRAM

3. The voltage of PP_VCC_MAIN after passing L1503 will change to PP_WLED_LX (PowerPositive_WhiteLED_Inductor) about 22V then forward and set the voltage value by Diode RECTIFIER, SCHOTTKY, 0.5A, 30V, SOD-923 D1501,
   output voltage after passing diode D1501 changed its name to PP_LCM_BL_ANODE or equal to VLED + on smartphone module in general.
   This PP_LCM_BL_ANODE voltage will be controlled by OVP Internal U1502 in case of excess voltage and control The current By SoC / CPU / AP:

• AP_BI_I2C0_SDA
  (Application Processor_Bidirect_I2C0_SerialDATA) on A1 U1502
• AP_TO_I2C0_SCL
  (Application Processor_Ke_I2C0_SerialCLOCK) * Introduction to data in A2 U1502
• AP_TO_PMU_AND_BL_DWI_CLK at foot B2 U1502 under SCK name
• AP_TO_PMU_AND_BL_DWI_DO at foot C2 U1502 with SDI Name

1. PP_LCM_BL_ANODE
   (PositivePower_LiquidCrystalModule_BackLight_Anode) which will go to J2019 Connector LCM B2B
   (Board to Board) via FL2024 first becomes PP_LCM_BL_ANODE_CONN
   Line PP_L

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