Download the MT6358vw Power IC Boot Sequence and Voltage Diagram. And Repair Your mobile help of this diagram.
Overview of MT6358 PMIC
The MT6358w PMIC supports various components like CPUs, GPUs, RAM, modems, and cameras. It regulates and supplies precise voltages through step-down (buck) and step-up (boost) converters, low-dropout regulators (LDOs), and other voltage regulators. Explain the Dead Boot Sequence Step By Step.
Key Components Connected to MT6358
CPU Power Rails:
VPROC12: Supplies the CPU core, with adjustable voltage ranging from 0.55V to 1.1V.
VPROC11: Provides additional core voltage, also adjustable between 0.55V and 1.1V.
VMODEM: Supports the modem's operation, with voltage ranging from 0.45V to 1.1V.
VGPU: Supplies power to the GPU, adjustable between 0.55V to 1.1V.
RAM and Storage:
VDRAM1: Dedicated for RAM, typically 1.25V.
VDRAM2/EMI VDDQ: Power for external memory interfaces, regulated at 0.6V.
VEMC: Supplies 3V for the embedded MultiMediaCard (eMMC) storage.
Peripheral Interfaces:
VSIM1 and VSIM2: Provide 1.8V for SIM card modules.
VIO28: Supplies 2.8V for sensors and other I/O interfaces.
VCN33: Delivers 3.3V for WiFi modules.
VCN18: Provides 1.8V for radio-frequency components.
Camera and Display:
VCAM1: Adjustable voltage between 1.8V and 3.0V for camera modules.
VCAM Main & TP: 2.8V for the main camera and a touch panel.
Miscellaneous:
VPH_Power: Main power rail, typically the input voltage from the battery.
VUSB: Supplies 3.07V for USB functionality.
VIBR: Powers the vibration motor, set at 2.8V.
Boot Sequence of MT6358
The boot process involves a predefined power-up sequence to ensure stable operation of connected components:
Primary Power Rail Initialization:
VPH_Power is activated, providing the base voltage for other regulators.
Core Power Supplies:
VS1 (2.05V) and VS2 (1.25V) are activated through HLDO and LLDO regulators.
VPROC12 and VPROC11 are initialized next, supporting CPU core functions.
Peripheral and Interface Rails:
VIO28 (2.8V) and VAUX18 (1.8V) are powered up to initialize I/O devices, sensors, and peripherals.
VEMC (3V) ensures storage is ready for read/write operations.
Memory and Modem Power-Up:
VDRAM1 (1.25V) powers up RAM.
VMODEM is activated to enable cellular connectivity.
Camera and RF Systems:
Camera-related voltages (e.g., VCAM1, VCAM Main) are powered according to the required specifications (ranging between 1.8V to 3.0V).
RF components receive power from VRF18 (1.8V) and VRF12 (1.2V).
Final Stabilization:
The PMIC ensures all voltage levels stabilize before releasing RESET_B (1.8V) to the CPU, signalling that the system is ready to boot.
Detailed Voltage Explanation for Each Section
1. CPU Power Supplies
VPROC12 and VPROC11: Adjust dynamically based on processing load, ensuring energy efficiency. During low-power modes, these voltages drop to the lower limit (0.55V).
Repair Tip: If the CPU doesn't boot, check the VPROC lines for proper voltage. Use an oscilloscope to measure ripple and ensure the values match the operational range.
2. RAM Power
VDRAM1 (1.25V): Critical for stable memory operation. Instability in this line can cause boot loops or application crashes.
Repair Tip: Check for short circuits or overvoltage conditions on the VDRAM1 line. Inspect capacitors and resistors for damage.
3. Modem and GPU Supplies
VMODEM: Power for cellular and data connectivity.
VGPU: Provides power to the graphics processing unit for rendering and display functions.
Repair Tip: If the device fails to connect to the network or shows display issues, inspect VMODEM and VGPU voltages.
4. Camera Interfaces
VCAM1 and VCAM Main & TP voltages vary by use case. Use a multimeter to measure their active and idle states.
Repair Tip: Issues with camera functionality often relate to the VCAM lines. Check for proper voltage during camera initialization.
Repair Guide: Common Issues and Fixes
1. No Power Issue
Symptom: The device doesn't power on.
Possible Causes:
No VPH_Power.
Faulty PMIC or mainboard damage.
Solution:
Verify battery voltage and check VPH_Power.
Replace the MT6358 if other components function correctly.
2. Boot Loop
Symptom: Device restarts repeatedly.
Possible Causes:
Unstable VPROC or VDRAM.
Watchdog reset triggered by CPU.
Solution:
Monitor VPROC12, VPROC11, and VDRAM1 voltages.
Replace capacitors or LDOs as needed.
3. Charging Problems
Symptom: The device doesn't charge.
Possible Causes:
Faulty VUSB (3.07V).
Damaged charging IC or connector.
Solution:
Measure VUSB output.
Inspect charging circuit components.