2 layers55 × 100 mm
2 layers17.4 × 12.6 mm
TC4056-Bypass
DoImant/TP4056-Power-Path-PCB52TP4056 Power Sharing PCB. Charge battery despite connected load.
- Size
- 17.4 × 12.6 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 8
- Nets
- 4
- Pads
- 12
- Tracks, vias
- 14, 2
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 6 (file 20211014)
- Created
- 24 Jun 2022
- Updated
- 24 Jun 2022
Overview
TC4056-Bypass is an open-source printed circuit board by DoImant, from the DoImant/TP4056-Power-Path-PCB repository on GitHub, published under the CC-BY-SA-4.0 licence. It is a 2-layer board of 17.4 × 12.6 mm with 8 parts on 4 nets, routed with 14 tracks and 2 vias.
It is built around the IRLML6402 and PMEG4010CEJ. Its parts include 5 connectors, 1 resistor, 1 diode and 1 transistor. It belongs with the power boards of this library.
Main components
2README
README.mdDescription
A problem with the TP4056 breakout circuit is that the load must be disconnected when the battery is being charged. This is because the charging circuitry detects when the charge current falls below C/10 (constant current charge mode near the end of the charge cycle). C is the battery capacity in mAh. When a load is connected to the battery, this changes the detected current, allowing the TP4056 to stop charging may never end!
A "bypass" consisting of an additional current path with a diode and a p-channel mosfet can help here. It is a controlled switch that disconnects the battery when an external power supply (e.g. solar cell) is connected.
The idea is that the P-channel FET will disconnect the battery from the load when a power source is connected to the charging chip. The TP4056 still charges the battery, but with no load. The load is directly from the power source powered. With a solar cell, the battery is disconnected when sufficient solar energy is available. If it generates more electricity than the load needs, the battery is also charged.
When the power source is removed, the P-channel FET conducts, connecting the load to the battery.
With this configuration, the TP4056 can safely charge the battery when the load is connected because the battery is charged during application external power supply is disconnected from the load.
The circuit presented here implements the load distribution. The board can be glued to the back of the TP4056-breakout and be connected to the existing soldering pads.
Connection example
A detailed explanation can be found here: detailed explanation
Have PCBs made: Aisler
Operation with solar cell
If the TP4056 breakout is operated with a solar cell, the maximum possible charging current must probably be reduced because, for example, 5V solar cells usually cannot deliver 1A charging current. A 2.5W solar cell with 5V generates a maximum charging current of 500mA. The adjustment is made on the TP4056 breakouts by swapping the resistor R3 (1.2kΩ).
| R3 (kΩ) | I-Bat (mA) |
|---|---|
| 10 | 130 |
| 5 | 250 |
| 4 | 300 |
| 3 | 400 |
| 2 | 580 |
| 1.66 | 690 |
| 1.50 | 780 |
| 1.33 | 900 |
| 1.20 | 1000 |
A value between 2kΩ and 3kΩ would be appropriate for a solar cell such as that listed above.
Parts
8| Qty | Value | Footprint | References |
|---|---|---|---|
| 5 | Conn_01x01 | Connector_Wire:SolderWire-0.5sqmm_1x01_D0.9mm_OD2.3mm | J1, J2, J3, J4, J5 |
| 1 | 10k | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R1 |
| 1 | IRLML6402 | Package_TO_SOT_SMD:SOT-23 | Q1 |
| 1 | PMEG4010CEJ | Diode_SMD:D_SOD-323_HandSoldering | D1 |
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Questions
How big is the TC4056-Bypass PCB?
It measures 17.4 × 12.6 mm and has 2 copper layers, 1.6 mm thick.
What parts does the TC4056-Bypass use?
8 parts, built around the IRLML6402 and PMEG4010CEJ. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the TC4056-Bypass KiCad files?
From the DoImant/TP4056-Power-Path-PCB repository on GitHub, at the commit this page was made from: the board is TC4056-Bypass.kicad_pcb and its schematic TC4056-Bypass.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the TC4056-Bypass design in my own project?
Its repository publishes it under the CC-BY-SA-4.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).