# Introducing DG002YI - An Upgrade from DG002JX

2022-09-05

I upgraded my power management module with a smaller form-factor.

# Previously…

I wrote a blog in May 2022 about the power management module DG002JX.

In this post, I’m going to talk about its upgraded version - DG002YI.

# Recap

In case you didn’t read the last post, DG002 series is about a small form-factor power management module that supports:

• USB 5V or DC (3.5+ V) to charge Li-ion battery.
• Li-ion to 3V3 conversion.

It is based on LTC3550. Feel free to take a look at the datasheet to learn more.

# What’s New?

• 2 more onboard LEDs to indicate the status. In DG002JX design, the LED is pin-out for driving the external LEDs.
• Most of the peripheral resistors and capacitors are 0402 footprint, which allows for a smaller PCB size.
• 7 pins (1.27mm pitch) to support solid connection to pin headers. Thus it can be an add-on module for other circuits.
• Smaller size: 14.0 x 9.7 mm. The length could be even smaller but I decided not to go that way. In comparison, DG002JX is 12.8 x 12.5 mm.
• (Bonus) Rotated component placement for better visual effects.
• Stack over the USB port to save space - no need to design the power management module individually anymore!

# Pin Out

On one side, there are 4 pins: DC_IN, USB_IN, 3V3_OUT, and GND. On the other side, the 3 pins are: 3V3_OUT, BATT, and GND. The redundancy （~3V3_OUT~ and GND) is for better and easier external PCB layout.

# Build It!

Like last time, I chose PCBWay to manufacture the boards.

My option is 1.0 mm thickness, 2-layer board, black color soldering mask, and white silk layer texts.

The board is tiny, but PCBWay handles it well. The boards came as exactly as I expected.

I also ordered the steel stencil from PCBWay to save both time and money. Note that they indicate the stencil option as “190×290mm SMD-Stencil, Non-framework Stencil”, but it came as a smaller size stencil, which is what I preferred. Because 190 x 290 mm is too large for this tiny board.

Check this photo for its great appearance:

(The dark stripes are due to the light source flicker.)

The next part is soldering. Stack SMD stencil onto the board, apply solder paste evenly on the board, place components, and bake it!

Everything is smooth except that I forgot to buy 0402 SMT 5k Ohm resistors. I have to use 0603 sizes instead, which is not optimal.

Here is a photo of what it looks like after soldering:

I would like to mention that I didn’t clean up the soldering aid paste and the focal point is on the bottom board. This image is not ideal. But the board functions well.

# Testing

Testing DG002YI is tricky because I don’t have an adapter board for it. It is difficult to test it stand-alone. My approach is - don’t test it. Put it onto where it is supposed to be and see how it performs.

I will update this part later, which is the tests like the voltage stability, heat dissipation, efficiency, etc. Stay tuned.

# Lesson Learned

I don’t see many concerns so far except for this one:

LTC3550 is not able to handle quick charge or USB-C-based charging protocol negotiation, which means, even if you use USB TypeC port to power the board, the module could not detect the presence of 5V at the USB_IN pin, thus fails to initiate the charging process. The solution is that I have to use a USB Type A - Type C cable for the board. For the AC-DC adapter, use USB Type A port instead of Type C.

Unless I replace the power management IC, otherwise this will be a long-lasting issue. I don’t mind this though. At least I can still leverage the old stock power adapter I collected in the past years.

# Epilogue

If everything performs well, I’m going to use PCB assembly services to batch build DG002YI. It benefits all my future projects!