Understanding OTG

By: Adam Swimmer

3 Min Read

25 Jul, 2022

LAVA SimulCharge adapters provide simultaneous charging and data access to select smartphones and tablets. It’s a technology unique to LAVA that ensures the mobile device remains a USB Host when it’s plugged into power. This is what allows the mobile device to communicate with USB peripherals while it is receiving a charge. LAVA’s Home Series adapters also feature a more common mobile adapter technology: OTG. This article will look at what OTG is and how it can be used.

What is OTG

Simply put, OTG stands for “On-the-Go.” It’s a mode available on many mobile devices that allows them to power and communicate with USB accessories. OTG adapters can connect mobile devices to Ethernet and various USB peripherals. 

The Charge-Plus LAN HUB, for example, is a USB-C adapter that provides both a reliable 10/100 Fast Ethernet connection and two USB-A ports for peripherals. If the adapter is for personal use, you might add a USB keyboard and mouse to get PC-like functionality out of your tablet. If the mobile device is being used in a kiosk setup or as a POS terminal, you might connect a barcode scanner and receipt printer.

OTG adapters don’t require external power as the mobile device can actually power the adapter and the connected peripherals. For OTG, it’s the data connection that’s a necessity, not power. In fact, the amount of power a mobile device can deliver in OTG mode is limited.

If the peripherals require more power than the device is capable of, you may need a powered USB hub. Powered USB hubs come with their own power supplies and so don’t use the mobile device’s battery. The hub would connect to the OTG adapter through USB. The adapter, in turn, would be connected to the mobile device through its USB-C or Micro USB power port. Any additional peripherals would then be connected to the powered hub instead of the adapter. The mobile device still remains in OTG mode. It is still USB Host and can still communicate with the peripherals through the adapter. However, the powered USB hub is what is actually powering them, not the mobile device.

SimulCharge Steps Up to the Plate

Using a Home Series SimulCharge adapter, such as the Charge-Plus or LAN HUB, you can also do similar setup with the tablet or smartphone powering from an AC power source through the adapter. In both SimulCharge and OTG mode, the mobile device remains USB Host. This is required for the mobile device to be able to interact with peripherals over USB.  A mobile device running on battery power is in USB Host mode by default. However, when it is charging, it loses its data access. This setup makes sense, considering most mobile devices only have the one USB port (USB-C or Micro USB). If the device is charging, there are not any free USB ports to plug anything else in.

However, a LAVA SimulCharge adapter allows the tablet or smartphone to both charge and communicate with peripherals. So, you can power the mobile device through a Home Series SimulCharge adapter using its USB power supply. Like with the battery power setup, you can connect the powered USB hub to one of the Charge-Plus’ USB-A ports and additional peripherals to the powered hub’s ports.

For this to work, you need to keep the power domains of the mobile device and powered USB hub separate. This means you need to purchase a powered USB hub that has an isolating diode, which is needed to prevent power feeding through from the power domain of the powered USB hub to the power domain of the mobile device’s power supply. Many cheaper powered USB hubs lack this functionality. If the hub attempts to deliver power to the adapter while it’s receiving power from the device, it will not work.

In Conclusion

While LAVA’s Charge-Plus SimulCharge adapters are capable of OTG, which most people use to both power peripherals from the mobile device’s battery, OTG has other uses. If the peripherals require more power than the mobile device can provide in OTG mode, you can hook up a third-party powered USB hub to the adapter. You can then add additional USB peripherals to the powered hub. OTG mode allows the mobile device to communicate with the peripherals but because the hub has its own power supply, it only draws data over the USB cable not power.