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| IPhone Charging Circuit Diagnostics Guide | |
|---|---|
| Type | |
| Device(s) | iPhone 7, iPhone 7 Plus |
| Difficulty | |
Description
iPhones that do not charge, charge intermittently, or only charge wirelessly often suffer from faults in the USB input, USB controller (Tristar / Hydra / Kraken), or charging IC power conversion stages.
This guide outlines a systematic voltage-based diagnostic approach to identify where charging fails.
Supported Models / USB Controller Generations
Tristar Models
- Expected voltages:
- PP_5V0_USB = 5 V
- PP_TRISTAR_PIN = 5 V
Hydra Models (up to iPhone 11 series)
- Expected voltage:
- PP_VBUS1_E75 = 5 V
Kraken Models (iPhone 12 series to 14 Series)
- Expected voltage:
- PP_VBUS1_E75 = 5 V
Diagnostic Steps
1. Check for 5 V Before the Charging IC
- Measure 5 V on the capacitor before the charging IC
- This confirms:
- Charger is supplying power
- Port and cable are delivering voltage
❌ No 5 V here = USB input / controller issue
✅ 5 V present = proceed to next step
2. Understand USB Verification Logic
- The charging IC does NOT know if the cable is good
- Cable validation is handled by the USB controller (Tristar / Hydra / Kraken)
If the USB IC cannot verify the cable:
- The device will not charge via cable
- Wireless charging may still work
3. Check USB Verification Line
If 5 V is missing at the USB controller, check:
- PP_VAR_USB_RVP_TIGRIS_R (also referred to as PP_VAR_USB_RVP)
This line is required for USB cable validation.
4. Check the 10 Ω RVP Resistor
Applicable to:
- iPhone 8 / X
- iPhone 13 / 14 / 15
Procedure:
- Locate the 10 Ω resistor on the VAR_USB_RVP line
- Measure voltage on both pads
- Both sides should show ~5 V
❌ Voltage on one side only = open resistor or downstream fault
❌ No voltage on both sides = upstream USB IC issue
5. Check PWR_GATE_EN_VBUS_1_VALID
- Measure voltage at the PWR_GATE_EN_VBUS_1_VALID test point
Expected result:
- 3.7 V – 5 V (any voltage above 0 V indicates the USB IC is functioning)
Interpretation:
- ✅ Voltage present → USB IC is working
- ❌ 0 V → USB IC is faulty or not powered
6. Wireless Charging Reference
- Wireless charging does NOT require USB verification
- If wireless charging works but cable charging does not:
- USB controller / RVP path is likely at fault
- Charging IC may still be functional
7. Charging IC Power Conversion
- Charging IC buck-converts 5 V → ~3.7 V
- This voltage is required for the battery to begin charging
If 5 V is present but battery does not charge:
- Suspect charging IC or its output stage
8. Check CHG_BOOT Line (Diode Mode)
- Locate the capacitor on CHG_BOOT
- Measure in diode mode
Expected readings:
- ❌ Same diode reading on both sides = fault
- From Tigris IC side → ~ 9 V
- From CHG_LX side → ~ 4 V
| USB IC Part Number | iPhone Model |
|---|---|
| NXP 1610A2 | iPhone 6, iPhone 6+ |
| NXP 1610A3 | iPhone 6s, iPhone 6s Plus, iPhone SE (1st Gen) |
| NXP 1610A3B | iPhone 7, iPhone 7 Plus, |
| NXP 1612A1 | iPhone 8, iPhone 8 Plus, iPhone X, iPhone XR, iPhone XS, iPhone XS Max,
iPhone 11, iPhone 11 Pro, iPhone 11 Pro Max, iPhone SE (2nd Gen) |
| NXP 1614A1 | iPhone 12, iPhone 12 mini, iPhone 12 Pro, iPhone 12 Pro Max |
| NXP 1616A0 | iPhone 13, iPhone 13 mini, iPhone 13 Pro, iPhone 13 Pro Max |
| NXP 1618A0 | iPhone 14, iPhone 14 Plus, iPhone 14 Pro, iPhone 14 Pro Max |