MediaTek vs Qualcomm Charging Section: Complete Repair Guide
If you repair smartphones, understanding the charging architecture differences between MediaTek and Qualcomm can save diagnostic time and prevent wrong IC replacements. This guide focuses on practical checks you can use on the bench.
Key Differences: MediaTek vs Qualcomm
| Parameter | Qualcomm | MediaTek |
|---|---|---|
| Code Resistor Position | Usually on battery positive line | Usually on battery negative line |
| Fuel Gauge Location | Inside charging IC or separate IC | Often integrated into power IC |
| VCDT Line | Typically not present in this form | Present and important for charge detection |
| Charging LDO Line | Not commonly used in this pattern | Commonly used for detection/support path |
How MediaTek Charging Path Works (Simplified)
5V enters from the Type-C port and passes through OVP/OBP protection to the charging IC. In many MediaTek designs, charge detection also depends on additional lines that feed the power IC:
- VCDT line: a divided sensing voltage path used for charging detection.
- Charging LDO line: an additional support/detection-related voltage path.
3 Must-Check Voltages (MediaTek Diagnostics)
- PMID: ~5V
- VCDT: ~0.5V (up to ~1.2V may still be acceptable depending on model)
- Charging LDO: ~2.8V
Typical Component Values (Model Dependent)
- VCDT divider example: R1 = 330k, R2 = 39k
- Charging LDO series resistor example: ~7.5k
- Common charging IC family: SGM41511 / BQ-compatible 24-pin types
Important Exception: Some 5G Platforms
Devices using combinations such as MT6365 + MT6360 may follow a different charging detection architecture, so the standard VCDT/LDO approach may not fully apply.
Bench Repair Checklist
- Verify VBUS to PMID path and confirm stable 5V input.
- Measure VCDT and inspect divider resistors for cracks, wrong values, or corrosion.
- Measure Charging LDO path and compare both sides of the series resistor.
- Check battery negative path code resistor and CSP/CSN sensing continuity.
- In liquid-damaged boards, inspect PMIC pads/balls and nearby resistor networks.
FAQ
Will replacing only the charging IC always fix no-charging issues?
No. In many MediaTek boards, power IC-side detection lines are also critical for charging detection.
If VCDT is 0V, what should I inspect first?
Start with the VCDT divider resistors, line continuity, corrosion points, and PMIC input pin integrity.
Can fuel gauge faults cause fake charging behavior?
Yes. Faults in CSP/CSN sensing paths or code resistor network can produce unstable battery reporting and charging anomalies.