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docs: Update unreleased changes in changelog and README

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- Fixed USB hub controller (U401/CH334): XO pin connected to GND for crystal-less operation
- Fixed DC/DC converter (U202/XR76208): Enable circuit changed to Zener diode for 12V operation
- Fixed USB outputs: Replaced fuses with TPS2557 power distribution switches for backfeed protection
This commit is contained in:
Eduard Iten
2025-12-23 07:27:59 +01:00
parent 2350a0b4e5
commit 5615fff072
17 changed files with 10132 additions and 8119 deletions
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README.md
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@@ -89,6 +89,7 @@ This board was designed to solve multiple critical issues commonly encountered i
### ⚡ DC/DC Converter (5V Output)
- **Controller:** MaxLinear XR76208 (Synchronous Step-Down, 8A, COT)
- **Input Voltage:** 12-24V DC (enable circuit with Zener diode)
- **Input Fuse:** 5A SMD 1812 Slow Blow
- **Reverse Polarity Protection:** SS56 Schottky diode
- **Output Voltage:** 5.1V (set via feedback divider: R_Top=15kΩ, R_Bottom=2.0kΩ)
@@ -99,7 +100,7 @@ This board was designed to solve multiple critical issues commonly encountered i
- **Stability:** Feed-forward capacitor (Cff) 1nF parallel to upper feedback resistor
- **Soft-Start:** 100nF at SS pin (~6ms startup time)
- **Current Limit:** 5.1kΩ resistor (~10.2A limit)
- **Enable:** Voltage divider from 24V (100kΩ upper, 22kΩ lower) = ~4.3V at pin
- **Enable:** Zener diode-based circuit for 12-24V input voltage range
### 🔌 Logic Power Supply (Power Path)
@@ -130,7 +131,7 @@ This board was designed to solve multiple critical issues commonly encountered i
- **Controller:** WCH CH334F (QFN-24)
- **Speed:** USB 2.0 High Speed (480 Mbit/s) with MTT
- **Clocking:** Internal (crystal-less), XI/XO pins left open
- **Clocking:** Internal (crystal-less), XO pin connected to GND for internal oscillator mode
- **Supply:** V5 to +5V_LOGIC
- **Upstream:** To Raspberry Pi Header (USB loopback cable required) or USB-C input
- **Downstream Ports:**
@@ -139,14 +140,16 @@ This board was designed to solve multiple critical issues commonly encountered i
- USB-A connector (vertical, for webcam)
**USB Port Protection:**
- **Concept:** 100µF electrolytic tank at +5V_PWR, followed by polyfuse, followed by 22µF ceramic at connector
- **Concept:** 100µF electrolytic tank at +5V_PWR, followed by TPS2557 power distribution switch, followed by 22µF ceramic at connector
- **USB-C Port (Screen):**
- Polyfuse: 4.0A hold current (hot chamber derating considered)
- CC Lines: CC1 and CC2 each with 10kΩ resistor to VBUS (behind fuse) for 3A advertisement
- TPS2557: Power distribution switch with backfeed protection, overcurrent/short-circuit protection
- Current limiting: Programmable limit via external resistor
- CC Lines: CC1 and CC2 each with 10kΩ resistor to VBUS (behind switch) for 3A advertisement
- ESD Protection: SRV05-4 TVS array
- **USB-A Port (Webcam):**
- Polyfuse: 1.5A hold current
- **ESD Protection:** SRV05-4 TVS array
- TPS2557: Power distribution switch with backfeed protection, overcurrent/short-circuit protection
- Current limiting: Programmable limit via external resistor
- ESD Protection: SRV05-4 TVS array
## 📋 Klipper Configuration