Team, When ES400 is in USB Host mode - what output current it can give to the attached USB device? USB stick works fine but customer is trying to use some kind of external sensor with ES400 and seems that there is not enough power coming from USB. They've managed to make it work only after connecting USB cable power lines to external source (PC USB port). They've measured the current coming from ES400 and claim it's 25mA. Is it expected value? Can it be increased? Will it be higher if using the high capacity battery? Thanks, Valery
ES400 USB host mode output current// Expert user has replied. |
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Hi All, The maximum current the ES400 can source in Host Mode is really 100mA. It has nothing to do with the capacity of the installed battery. The electronics that supply the current from this interface are electrically limited to 100mA. When the ES400 is in Host mode the 100mA is always available - you don't need an application API to enable it.
Well, ES400 User Guide says that USB output power is 5V @ 100mA max. The external sensor specs for inpout USB power are 5V @ 80mA typical and 500mA max. So at least the max value is out of our specs which may be the reason why the sensor does not work. For those curious I'm attaching the sensor manual. Maybe someone has already faced this device in the projects? Still couple of questions for ES400 experts:
1. Is 100 mA max a correct value? We all know that sometimes our documentation is not quite precise... 2. May the output power depend on the battery type (standard vs high capacity)? 3. Is the power is always on on the USB when in host mode or it must be turned on explicitly (programmatically by the application)? Thanks, Valery