CIY68 keyboard lithium battery/dry battery dual-power automatic switching circuit

Updated printing files for switch and opening templates.
The component cost is about 5 yuan.
 
This project has become the current version after 3 iterations. The main implementation is: 1. The TYPE-C rechargeable lithium battery is converted into a 3.3 step-up and step-down DCDC to power the core board HS6620. There is an independent switch to control DCDC, and a single charging light prompts (on and off when fully charged) ).
2. DCDC adopts step-up and step-down DCDC to solve the problem that the output of step-down DCDC is lower than 3.3 as the battery voltage decreases. When the step-up and step-down DCDC Vin parameter is lower than the cut-off voltage parameter of the battery protection board, it can be guaranteed to be directly cut off from 3.3v to 0v. . The IC uses the cheapest TX4310B from Lichuang Mall, and the measured maximum current of 150ma can completely drive it.
3. Retain the most advanced dual AAA battery power supply function, and meet the requirement that when the total battery voltage is less than the lithium battery step-up DCDC output (3.3V), Pmos is blocked and will not be output to the keyboard board step-up DCDC.
4. Version 2.1 uses a simple and perfect diode circuit to solve the problem of lithium battery loss after studying the solutions of seniors in various electronic forums. After Pmos is turned on, the AAA battery is transmitted back to the Pmos gate through the keyboard's built-in boost circuit, causing frequent switching oscillations and unstable voltage. Case.
 
Welding instructions:
VCC3+ → AAA battery compartment positive pole
VCC3- → AAA battery compartment negative
pole OUT+ → Keyboard 2Pin plug wire positive pole
OUT- → Keyboard 2Pin plug wire negative pole
BOUT+ → Welded to the lower left solder joint of the tantalum capacitor on the keyboard board.
 
Installation instructions:
Although the USB is 3D printed And the switch opening template, but in actual use, it is easier to cut it directly with a soldering iron and then rub it slightly for trimming.
It is not recommended to open a hole for LED. Just use a soldering iron to dig a hole to allow light to shine through.
The battery I used is 803562 2500mAh, which is sufficient for actual use. I cut idle yoga mats in other empty areas of the keyboard, but they feel useless.
I originally wanted to 3D print the card holder for fixing the circuit board and battery, but later I directly glued it with thermally conductive silicone (not silicone grease). In fact, double-sided tape and glass glue are no problem.
In fact, I originally wanted to change the true three-mode model, but later I felt that it was not necessary, but the matrix diagram was already drawn, so I wanted to do it myself.
 
About the panel:
The panel file is a positioning plate cut from 1.5mm acrylic. Even if I had a coupon, I had to call it three times and spend tens of dollars to finally install it. . .
The main purpose is to reduce the weight of the keyboard, because I mainly use CIY for office work and business trips.
The small keyboard in the panel is a new pit created to solve the problems of the CIY68 office where the CAPS light is not always on and cannot be distinguished, and the calculator input is troublesome. Logitech K270 master control is scheduled to implement a single-knob 6-function small keyboard without an additional MCU. As for When will you fill in the hole? Let’s just let it happen￣▽￣