USB-PD AC Adapter

This page describes the USB-PD AC adapter requirements for the Zudo Power USB-PD power supply module.

Required Specifications

Why 15V / 3A?

This power supply uses the STUSB4500 USB-PD controller to negotiate 15V from the adapter. The STUSB4500 is configured via NVM to request specifically 15V PDO (Power Data Object).

Power Budget Calculation:

Accounting for conversion efficiency (~75-80%), the input power required is approximately 35-40W. A 45W adapter (15V/3A) meets this requirement with some margin.

Important Considerations

1. Must Support 15V PDO

Critical: The adapter must explicitly support 15V in its PDO profile.

Some cheaper adapters only support:

• 5V / 9V / 20V (skipping 15V)

Always verify the product specifications list 15V as a supported voltage.

2. Single Port Usage (For Single zudo-PD)

When using multi-port adapters with a single zudo-PD unit, power is typically split between ports. For reliable operation:

• Use single USB-C port for full power delivery

• If using multi-port, ensure the port supports 45W+ when used alone

Note: For multi-case setups with multiple zudo-PD units, using a single high-wattage multi-port charger is actually recommended. See Multi-Case Setup below.

3. GaN Technology Recommended

GaN (Gallium Nitride) adapters offer:

• Smaller size

• Higher efficiency

• Lower heat generation

• Better reliability

4. Avoid No-Brand Adapters

Cheap no-brand adapters may:

• Have unstable voltage output

• Skip 15V PDO entirely

• Lack proper safety certifications (PSE in Japan)

Recommended Products (Amazon Japan)

Top Recommendations

Product Links

1. Anker Nano II 65W - Best overall choice

• Compact design with GaN II technology

• Proven reliability

• Output: 5V/3A, 9V/3A, 15V/3A, 20V/3.25A

2. Anker Nano II 45W - Minimum spec, most compact

• Smallest form factor

• PPS support

• Output: 5V/3A, 9V/3A, 15V/3A, 20V/2.25A

3. UGREEN Nexode 65W - Best value with multiple ports

• 3 ports for versatility

• GaN II technology

• PD3.0 and PPS support

4. BESTEK G651CA1 65W - Budget option

• Explicitly lists 15V/3A support

• Compact design (~102g)

5. Belkin WCH013dq 65W - Premium option

• Trusted brand

• 5V/9V/12V/15V/20V support

• Dual USB-C ports

6. CIO NovaPort SLIM 45W - Ultra-thin design

• Only 13mm thick

• Dual USB-C ports

Verification Before Purchase

Before purchasing, check the product page for:

1. PDO List - Should include 15V (e.g., "5V/9V/15V/20V")

2. Power at 15V - Should be at least 3A (45W)

3. Safety Certification - PSE mark for Japan

4. Reviews - Check for stability issues

USB-PD Controller Compatibility with Multi-Port GaN Chargers

Known Issue: High-Wattage Multi-Port Chargers May Not Work

Important Discovery: Some high-wattage multi-port GaN chargers may have compatibility issues with simple PD sink controllers. The v1.1 design uses STUSB4500 which has significantly better charger compatibility (~95%+) compared to the v1.0 CH224D design (~33%).

Confirmed Working

Confirmed NOT Working

Why This Happens

Simple PD sink controllers may have limited negotiation capabilities compared to the sophisticated software PD stacks in laptops and tablets. Multi-port GaN chargers with intelligent power management expect active, responsive PD sinks.

Comparison: Simple vs Advanced PD Controllers

The STUSB4500 used in v1.1 addresses most of these issues with USB-IF certification and built-in retry logic.

Root Causes

1. Dynamic Power Management Interference

Multi-port chargers constantly redistribute power as devices connect/disconnect. Features like:

• Anker PowerIQ / ActiveShield - Proprietary device detection

• Dynamic PDO re-advertisement - Changes available power in real-time

• Intelligent power sharing - May confuse simple sink controllers

2. Non-Standard Timing

Some high-wattage chargers:

• Output 0V initially until specific conditions are met

• Have longer negotiation sequences

• Use stricter CC line detection than USB PD specification requires

3. Missing 5V PDO (Some Chargers)

Some chargers violate USB PD specification by not including 5V as PDO1:

• USB PD spec requires 5V as the first PDO

• When CH224D receives Source_Capabilities starting at 9V, negotiation fails

• Device falls back to pre-PD 5V default (insufficient for zudo-PD)

Symptoms When Charger Is Incompatible

When connecting zudo-PD to an incompatible charger:

1. Only the -12V LED briefly flickers

2. All LEDs turn off

3. No output voltage on any rail

Explanation: With only 5V input (failed negotiation), the DC-DC converters cannot produce proper voltages. The ICL7660 voltage inverter briefly attempts to invert whatever voltage exists, causing the -12V LED to flicker momentarily.

Recommendations

For Best Compatibility

Recommended Approach

1. Use a dedicated single-port charger for zudo-PD

2. Test before purchasing - If possible, test with your specific charger before committing to a setup

3. Avoid high-wattage multi-port GaN chargers unless confirmed working

Multi-Case Setup Caveat

The Multi-Case Setup section recommends multi-port chargers for ground loop elimination. However, due to potential compatibility issues:

• Preferred: Use confirmed-working chargers (like Anker Nano II series)

• Alternative: Accept separate adapters with proper ground management

• Testing required: Always test multi-port chargers before relying on them for live performance

STUSB4500 Improves Compatibility (v1.1)

The v1.1 design uses the STUSB4500 USB-IF certified controller, which significantly improves charger compatibility (~95%+) compared to the v1.0 CH224D design (~33%). The STUSB4500 includes built-in retry logic and error recovery that resolves most compatibility issues with modern GaN chargers.

Troubleshooting

Adapter Not Working

If the power supply doesn't work with your adapter:

1. Check PDO support - Adapter may not support 15V

2. Check cable - Use a USB-C cable rated for 3A or higher

3. Check port - Some multi-port adapters reduce power on certain ports

LED Not Lighting

If LED2 (power indicator) doesn't light:

1. Verify adapter is connected and powered

2. Try a different USB-C cable

3. Verify adapter supports 15V PDO

Multi-Case Setup (Multiple zudo-PD Units)

When you need more power for a larger modular synth system, you can power multiple zudo-PD units from a single multi-port USB-PD charger. This approach has significant benefits over using separate AC adapters.

Why Use a Single Multi-Port Charger?

Ground Loop Elimination:

When using separate AC adapters for each case, connecting modules via patch cables creates ground loops:

Separate Adapters (BAD):
┌─────────────────┐          ┌─────────────────┐
│   Adapter A     │          │   Adapter B     │
│   GND_A         │          │   GND_B         │
└────────┬────────┘          └────────┬────────┘
         │                            │
    ┌────┴────┐                  ┌────┴────┐
    │ Case A  │◄───patch cable───│ Case B  │
    └─────────┘   (has ground)   └─────────┘
         │                            │
         └─────── ground loop ────────┘
              ↑
         Potential 50/60Hz hum

Single multi-port charger solves this:

Single Multi-Port Adapter (GOOD):
┌─────────────────────────────┐
│  Multi-Port GaN Charger     │
│  (shared internal ground)   │
└──────┬─────────────┬────────┘
       │             │
   ┌───┴───┐     ┌───┴───┐
   │zudo-PD│     │zudo-PD│
   │ Case A│◄───►│ Case B│  ← Patch cables OK!
   └───────┘     └───────┘

No ground loop - both share same ground reference!

Power Requirements

Each zudo-PD unit requires approximately 40W at 15V (15V × 2.5A with some margin).

Important Considerations

1. 15V must be maintained on all ports - Some chargers drop to 9V when power is split

2. Check simultaneous output specs - Not just total wattage, but per-port when multiple ports are used

3. USB Hubs don't work - Regular USB hubs only provide 5V, not USB-PD

⚠️ Critical Compatibility Warning

The multi-port chargers listed below have NOT been tested with zudo-PD. Based on our testing (see USB-PD Controller Compatibility), high-wattage multi-port GaN chargers often fail to work with the CH224D controller (v1.0 design). The STUSB4500 (v1.1) improves this significantly.

Confirmed NOT working:

• Anker Prime 200W (A2683) - ❌ All ports fail

• Elecom EC-AC67150BK (150W) - ❌ All ports fail

Before purchasing any multi-port charger for multi-case setup:

1. Check if the specific model has been tested with CH224D-based devices

2. Consider using multiple single-port chargers instead (with ground loop mitigation)

3. Test before relying on for live performance

Multi-Port Chargers (Untested - Use at Your Own Risk)

The following chargers have sufficient power specifications but have not been verified to work with zudo-PD:

For 2 zudo-PD Units

For 3 zudo-PD Units

Note: If you find a multi-port charger that works with zudo-PD, please report it so we can update this list.

Verification Checklist

Before purchasing a multi-port charger for multi-case setup:

• [ ] Total wattage ≥ (number of units × 45W)

• [ ] Supports 15V PDO on multiple ports simultaneously

• [ ] Check reviews for multi-device usage scenarios

• [ ] Verify power distribution when all ports are used (check manual or QR code specs)

Alternative: Separate Single-Port Adapters

Given the compatibility issues with multi-port GaN chargers, using separate single-port adapters may be more reliable:

Pros:

• ✅ Confirmed working (Anker Nano II 65W tested)

• ✅ Simple, predictable PD negotiation

• ✅ Each unit has dedicated power

Cons:

• ⚠️ Potential ground loops when connecting patch cables between cases

• ⚠️ More wall outlets needed

Ground Loop Mitigation (if using separate adapters):

1. Use balanced audio connections where possible

2. Ground lift on one case (if your synth supports it)

3. Use the same power strip for all adapters (shared AC ground)

4. Avoid connecting patch cables between separately-powered cases during performance