Jorian Zwerver
19b8948104
24V Supply for HCM
This repository contains all project files for the 24V supply for the HCM and hydrofoil actuators. Below is an explanation of all features and how to interpret the diagnostic measurements.
Table of Contents
Pinout
The 24V board has 8 connectors, for which the pinout is outlined below. The labels for each connector are also shown at the bottom of the PCB.
Underside of PCB, showing labels.
J1
| Pin | Label | Description |
|---|---|---|
| 1 | VBATT | Battery voltage (15 - 75V accepted) |
| 2 | GND | Ground |
J2
| Pin | Label | Description |
|---|---|---|
| 1 | 24V | 24V output, 6.5A limited. |
| 2 | GND | Ground |
J3
| Pin | Label | Description |
|---|---|---|
| 1 | DIS | Disables 24V output when pulled high. |
| 2 | PG | Indication of output status. 24V is present when high. |
| 3 | IMEAS | Gives voltage proportional to current, read more here. |
| 4 | GND | Ground |
J4
| Pin | Label | Description |
|---|---|---|
| 1 | 24V | 24V output, 6.5A limited. |
| 2 | GND | Ground |
J5
| Pin | Label | Description |
|---|---|---|
| 1 | DIS | Disables 24V output when pulled high. |
| 2 | PG | Indication of output status. 24V is present when high. |
| 3 | IMEAS | Gives voltage proportional to current, read more here. |
| 4 | GND | Ground |
J6
| Pin | Label | Description |
|---|---|---|
| 1 | 24V | 24V output, 6.5A limited. |
| 2 | GND | Ground |
J7
| Pin | Label | Description |
|---|---|---|
| 1 | DIS | Disables 24V output when pulled high. |
| 2 | PG | Indication of output status. 24V is present when high. |
| 3 | IMEAS | Gives voltage proportional to current, read more here. |
| 4 | GND | Ground |
J8
| Pin | Label | Description |
|---|---|---|
| 1 | 3V3 | 3V3 power for circuit logic. Should be provided externally. |
| 2 | DIS_24V | Disables the 24V buck converter when pulled low. |
| 3 | DIV_24V | Gives an voltage proportional to the 24V bus. Read more here. |
| 4 | GND | Ground |
Dimensions
All dimensions in mm.
Using the board
To use the board, follow the following steps:
- Connect the input to 48V (15 - 75V).
- Supply 3V3 and GND to J8. This is needed for the IC's and input switch to work.
- Then the board is functional! 24V should be at the outputs. Using J8, the whole board can be disabled and the output voltage of the converter can be measured. Using J3, J5 and J7, diagnostic data can be read from the protection devices and the devices can be disabled.
Output protection
There are three 24 VDC output ports. These are protected against overcurrent and short circuits using the TPS259807ONRGER. It is set to:
- It triggers in overcurrent after 6.5A. It accepts an overcurrent between 6.5 - 8 A for 10 us, then it will also shutdown.
- The device has overtemperature protection.
- It is protected against an undervoltage of 19.2V. It has no overvoltage protection.
- When starting up, the device will precharge its output. This takes 1 ms.
- After a shutdown event, the device will wait for 1 ms and restart the output. After four tries, it will indefenitely close. It can be manually restarted by pulling the reset pin low (on J3, J5 and J7).
Current sensing
The output protection device outputs an voltage proportional to the current through the device (the IMEAS pin on J3, J5 and J7).
The relation between voltage and current is:
V_{IMON} = G_{IMON}I_{OUT}R_{IMON}
Here, G_{IMON} = 246 uA/A and R_{IMON} = 1500 \Omega. Combining gives:
I_{OUT} = \frac{V_{IMON}}{G_{IMON}R_{IMON}}
I_{OUT} = 0.369 \cdot V_{IMON}
Voltage sensing
The output voltage of the converter can be measured using the DIV_24V pin of J8. Using a voltage divider, the voltage on the DIV_24V pin is relative to the voltage on the output. The voltage divider is shown below.
The voltage divider to measure the output voltage.
The output voltage and divider voltage are related by:
V_{OUT} = V_{DIV\_24V} \frac{R1 + R2 + R3}{R2 + R3}
V_{OUT} \approx 9.197 \cdot V_{DIV\_24V}
24V Converter
The used 24V converter is the RPMGQ12-20. It accepts an input voltage between 18 and 75 VDC. The output is set to 24 VDC. The efficiency curve is shown below.
The efficiency of the RPMGQ12-20 against different input voltages.
Output files
For this project:
- A schematic can be found using the link.
- All production files for JLCPCB are in this folder.
License
Copyright 2026, Stichting Spectrum Solarteam
Permission is hereby granted, free of charge, to any person obtaining a copy of this hardware and associated documentation files (the "Hardware"), to deal in the Hardware without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Hardware, and to permit persons to whom the Hardware is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Hardware.
THE HARDWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE HARDWARE OR THE USE OR OTHER DEALINGS IN THE HARDWARE.