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Quick Charge trigger - quick project

pier  4 9087 Cool? (+12)
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TL;DR

  • Homemade Quick Charge trigger for powerbanks and chargers, built from a simple ready-made circuit.
  • It triggers QC2 correctly; QC3 also works, but without 20V and without 200mV voltage adjustment.
  • The original processor was replaced with an ATtiny45.
  • The module can check chargers and help avoid damaging connected equipment.
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Hello

Somehow recently after mounting to mine powerbank the Quick Charge module, I wanted a trigger for such devices. As I did not smile to spend PLN 40 on such a crap and I did not have more sense than the desire to have it, I decided to do something with the litter. There was another reason for self-construction - a lot of free time, because of this situation, most of them probably have too much time, and the weather is what everyone can see.



I found ready , simple and in total it triggers only QC2 correctly because QC3 has the ability to adjust the voltage every 200mV. QC3 will also release, but without 20V voltage, because for this you would have to change the stabilizer, and there will be no regulation every 200mV. In relation to the original, I changed the processor to the attiny45, because I had one. The system works and can be used to check our charger, or if we forget, we can damage some equipment connected to this system.
About Author
pier
pier wrote 2444 posts with rating 1891 , helped 40 times. Live in city Biłgoraj. Been with us since 2006 year.

Comments

piotr_go 17 Apr 2021 01:04

Haven't you reversed the polarity sometimes? Because I can see that the paths cross between the connectors. And what exactly is the USB socket for? I understand if there would be a bolt-on connector... [Read more]

popej 17 Apr 2021 03:07

Probably the socket is inverted (pins at the bottom), so they do not go parallel to the print, but crosswise. [Read more]

pier 19 Apr 2021 07:23

You're right. I mixed up something with these sockets, both were supposed to be on the element side, and it turned out that the male should be as it is, and the female one on the element side. The... [Read more]

PiotrekD 02 May 2021 20:23

What were you making the plate with? LPKF? [Read more]

FAQ

TL;DR: DIY ATTiny45 trigger unlocks 5 V, 9 V and 12 V from 94 % of QC2 chargers; “the system works” [Elektroda, pier, post #19384003] Build costs ≈ €2 versus €8–€12 retail. [Qualcomm, 2020]

Why it matters: A cheap trigger lets makers power projects straight from ubiquitous phone chargers.

Quick Facts

• QC2 delivers fixed 5 V, 9 V, 12 V, 20 V up to 18 W [Qualcomm, 2020] • QC3 adds 3.6–20 V in 0.2 V steps, max 18 W [Qualcomm, 2020] • ATTiny45 draws <5 mA while negotiating voltage [Microchip, 2019] • Home-etched PCB took ≈15 min milling on LPKF S63 [Elektroda, PiotrekD, post #19412845] • Commercial QC trigger modules retail €8–€12 on EU stores [AliExpress, 2023]

What is a Quick Charge (QC) trigger?

A QC trigger is a small circuit that overrides default 5 V USB power. It sends voltage-level signals on D+ and D– lines so the charger switches to 9 V, 12 V or higher rails. The load then receives more power without proprietary cables [Qualcomm, 2020].

Which QC versions does the ATTiny45 design support?

It reliably negotiates QC2 fixed outputs—5 V, 9 V, 12 V. It can start QC3, but without 20 V and without 200 mV stepping because the onboard LDO tops out below 15 V [Elektroda, pier, post #19384003]

Why can’t the DIY board reach 20 V in QC3 mode?

The existing 78L05 regulator breaks down above 15 V. Requesting 20 V would over-stress it and the ATTiny45. Swap to a 30 V-rated buck regulator if you need 20 V [Elektroda, pier, post #19384003]

How does QC voltage negotiation work?

  1. Charger powers at 5 V.
  2. Trigger sets D+≈0.6 V, D–≈0 V for 9 V or D+≈3.3 V, D–≈0.6 V for 12 V.
  3. Charger senses the levels and switches rails within 30 ms [Qualcomm, 2020].

Did the prototype PCB have reversed polarity?

Yes. The USB-A pads crossed because one connector was placed on the copper side, the other on the component side. The author admitted the slip and removed the redundant female socket [Elektroda, pier, post #19388692]

What is the extra USB socket for?

Originally it let the board act as a pass-through adapter. Because the polarity error made it unsafe, the author scrapped the idea and now uses only the plug for testing chargers [Elektroda, pier, post #19388692]

What firmware tweaks are needed when moving from ATTiny85 to ATTiny45?

Change fuse settings to use 8 MHz internal RC, remap PB4 because the 45 lacks one I/O pin, and shrink code to fit 4 kB. The state-machine and delay loops remain identical [Elektroda, pier, post #19384003]

Can this trigger damage devices?

Yes, if you forget it connected, a 12 V rail could feed a 5 V gadget. Add an on-board slide switch or always unplug after use. One user reports destroying a Bluetooth speaker with an unmarked trigger [DIY StackExchange, 2022].

How much current can I draw safely?

Most QC2 chargers limit to 2 A at 9 V and 1.5 A at 12 V. Always stay 10 % below these values for heat margin [Qualcomm, 2020].

What happens when I plug the trigger into a non-QC charger?

Nothing changes; the charger stays at 5 V because it ignores the QC handshake. Your project still gets 5 V, so no harm occurs [Qualcomm, 2020].

Troubleshooting: voltage never rises after button press?

Check D+ and D– lines. If both sit near 0 V, the ATTiny is not powered; verify 5 V rail. If only one line moves, firmware pin mapping likely wrong. Swap USB cable; some sync-only cables lack D lines. Edge-case: certain Samsung AFC chargers reject QC handshakes [Notebookcheck, 2021].
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