How Charging Works in MTK Phones: PMU, VCDT, CHG_LDO, and Sense Resistor Full Explanation” скачать в хорошем качестве

How Charging Works in MTK Phones: PMU, VCDT, CHG_LDO, and Sense Resistor Full Explanation”

📲 Join Our Online Mobile Repair Course – Start Learning Today! ✅ Learn from anywhere ✅ Step-by-step videos with real board testing ✅ Full PDF notes and schematics ✅ Direct WhatsApp support from instructors ✅ Learn basic to advanced motherboard repair 💬 WhatsApp Us Now to Join! 📞 [+918901794940] 🔋 MTK Charging Section Full Description – Explained with Diagram The charging section in MTK-based smartphones is one of the most critical areas for repair technicians. It involves multiple components working together to ensure safe, efficient, and intelligent charging of the battery. Below is a complete breakdown: ⚙️ 1. PMU (Power Management Unit) – The Brain of Power Distribution The PMU or Power Management IC in MTK phones controls power distribution across the motherboard. It monitors and manages: Battery voltage Input voltage (from charger) Charging current Overvoltage/Undervoltage protection Thermal protection The PMU communicates directly with the charging IC and the main CPU to decide when and how the battery should be charged. ⚡ 2. VCDT Line (Voltage Charger Detection) The VCDT (Voltage Charger Detect) line is a crucial signal line that helps the PMU detect when a charger is connected. When a USB charger is plugged in, a voltage appears on the VBUS line. This voltage is sensed via the VCDT line, and the PMU activates the charging circuit accordingly. If this line is missing or faulty, the phone won’t detect the charger. 📌 TIP: Always check for continuity and proper voltage (~5V) on this line when troubleshooting "charging not detected" issues. 🪛 3. CHG_LDO Line (Charge Low Dropout Regulator) The CHG_LDO (Charge Low Dropout Regulator) is used to stabilize the voltage that powers the charging IC and related transistors. Provides a clean, regulated voltage (typically ~4.4V to 5V) Essential for pre-charging, USB OTG, and other low-voltage operations 📌 Fault symptom: If CHG_LDO is missing, the phone may show “charging” but the battery percentage will not increase. 🔄 4. Charging IC (Charger IC) – The Power Controller The charging IC is responsible for actual battery charging, and works under the control of the PMU. Manages charging stages (pre-charge, fast charge, trickle charge) Regulates current and voltage going to the battery Works with I²C/SPI protocol to communicate with the CPU