Installation Guide for VREG2 USB-C Power Adapter Board
Rosahl membrane electric dehumidifiers
Rosahl is a unique solid state dehumidifier that removes moisture from enclosures using electrolysis when a low voltage (3V DC) is applied. Rosahl is growing in popularity as it provides clean moisture extraction and low cost, maintenance free performance.
The VREG2 Series power adapter boards offer a simple and convenient way to convert a 5V USB supply to a 3V DC current limiting output. They are suitable for Rosahl micro-dehumidifier membranes ranges PD, RD, RS, M-1J, M-2J, M-3M, M-3J and MDL-3. The pre-wired VREG2 power adapter boards are integrated within the MDL and M-Series mounting kits.
For stand alone applications, three simple mounting bases are:
Standard VREG2 Power Adapter Board
This simple VR2-FMC base-mounting module accepts the VREG2 USB-C power adapter board, Its compact low-cost design is simple to install with two screws.
The VR2-PMC is a simple 22mm barrel mounting module where the VREG2 USB-C power adapter board mounts inside the barrel. It is designed for applications where the 5V power source is outside the enclosure being dehumidified.
Prewired VREG2 used with mounting kits
The VRS and VRD prewired VREG2 boards are primarily for installation in the membrane installation kits and the cables are sized for this purpose. Please check their suitability before ordering them for other installations.
VRS-330 uses the same VREG2 circuit board but includes prewired 60mm output cables and connectors for use with the M1J, M2J, M3M and M3J membranes in the M-Series mounting kits.
VRD-330 also uses the same VREG2 circuit board and includes prewired 40mm output cables and connectors for use with the MDL-3 in the MDL-Series mounting kits.
VREG2 Technical Information
Fold-Back Current Limiting
The dehumidifier membranes can hold humidity if no supply voltage is present. This moisture needs to be discharged on startup and can lead to a higher inrush-current than the regular operating current. During startup the supply voltage should not fall below 2V, otherwise moisture discharge is not possible or significantly delayed. The use of fold-back current limiting regulates the output current to maintain the required minimum supply voltage for the dehumidifier membranes.
The RT9059 voltage regulator used on the USB-C-VREG2 contains an independent current limit and the short circuit current protection to prevent unexpected applications. The current limit monitors and controls the pass transistor’s gate voltage, limiting the output current to 3.1 A (typical). When the output voltage is less than 0.2v, the short circuit current protection starts the current fold back function and maintains the loading current at maximum 1.8A. The output can be shorted to ground indefinitely without damage.
Technical Parameters
VREG 2, VRS-330, VRD330
| Symbol | Parameter | Condition | Min | Typical | Max | Units |
| VIN | Input voltage | USB-C | 3.3 | 5 | 5.5 | V |
| VOUT | Output Voltage | 3.0 | V | |||
| IOUT | Output current [1] | Rated | 3000 | mA | ||
| Output accuracy | 85°C | 1.5% | ||||
| IQ | Quiescent current | 0.6 | mA | |||
| Current limiting | Fold-back | |||||
| T | Operating temp. | -40° | +85° | C | ||
| Dimensions | 25 x 16 x 4 | mm |
Note
[1]: The voltage regulator of the USB-C-VREG2 is specified for a rated output current of 3000mA. However, with a 5V USB-C supply voltage this leads to a thermal power dissipation of 6W. Continuous operation at 3000mA would hence require cooling. The intended application of the USB-C-VREG2 is with a Rosahl M-series dehumidifier membrane e.g., M-1J1R, M-2J1R, M-3M1R, M-3J1R and MDL-3 which draw high inrush.
USB Power Supply
The VREG-2 is not an official USB-C PD (Power Delivery) sink device and may not be recognised by some PD or special purpose USB-C power supplies. In the event of a problem, try it with a standard 15W USB power supply.
Cautions:
Prior to mounting in an enclosure, the VREG2 power adapter boards may be damaged by electro-static discharge (ESD) and should be handled appropriately trained personnel.
The VREG2 should not be operated without protection circuitry if connections to the product’s pin header rows are longer than 3m.
Manufacturer in the European Union
Declaration of RoHS available
Declaration of REACH Directive available
Version 2.2
Westside-International Ltd
Boston House, Downsview Road, Wantage, Oxfordshire, OX12 9FF. UK