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A loop transmitter is a current source. So the question refers to "do you know to design a precision current source"? What are your specifications? Emulating self-powered or loop-powered transmitters, accuracy? TI XTR ICs can be surely used. Also any other dedicated 4-20 mA transmitter or DAC with current loop output like AD420.
You say it's a self-powered USB device and you observe VCC to GND short of the MCU. Possible reason is either VCC overvoltage or supply latch-up triggered by a CPU IO pin. I presume the chip analysis could tell more to narrow down the failure mechanism, but apparently there have been no significant results provided. Apart from chip analysis,
Hi I have a circuit (rf preamplifier) that can be powered from 0.8v to 5v. Higher voltage is at benefit, to increase dynamic range. I consider two batteries for it (it has to be a single cell at about the AAA diameter): 1. AAA 1.2v Ni-MH low self discharge. 2. 10440 Lithium ion battery 3.7v Obviously 2 is better, however the li-ion cannot be disc
you can use the USB self powered topology (Use D+, D- and Ground, don't use the USB ports +5V to your system)
What's the voltage on the USB signaling lines? 3.3V or 5V? Is the ground of the USB connector (reference potential) connected to your self powered circuit? A block diagram of your circuit, or a few pics could be helpful to get a better view on the problem.
The USB standard specifies that self-powered devices shall monitor VUSB to detect attachement and detachment. An USB device designed in concordance with the standard thus won't operate without VUSB. Your self-elaborated PIC device possibly will.
I am designing and building device that will work outdoor self-powered using solar panel and battery. Solar panel rated 10W gives Im=0.65A (short-circuit) and has power peak at Um=16.8V (21V open-circuit). The VRLA battery from Yuasa is rated 4Ah 12V (13.65V floating). I followed data sheet and designed circuitry with C/10 loading (no timer) so for
If the 0.163928mAh/d number is right, the system would probably better run from a non-rechargable Lithium battery. There won't be noticeable discharge of the NiMH battery, self-discharge may be higher than regular load.
You shouldn't disregard the PIC datasheet any longer. It's describing the purpose of each USB related pin rather detailed. As a first step, you should become clear about intended device operation, USB-powered or self-powered. VBUS pin will be needed for attachment detection in a self-powered application.
Referring to the original question powered-off (...) If a hub was configured while the hub was self-powered, and then if external power is lost, the hub must place all ports in the powered-off state. If the hub is configured while bus powered, then the hub need not change port status if the hub (...)
You can change the PIC18F2550 operation from bus powered to self powered.
This is just one example from many : self-powered Dummy Load Checks Out Multiple-Output Power Supplies course circuits can be adjusted to your current needs.
Hello, Battery backup lighting for emergency signs is governed by standards which govern the intervals between battery self tests etc. Do you know where i can get the book of standards for this?
A typical 4-20 mA current loop configuration uses a positive supply of 15 - 30 V and a ground referenced shunt. self powered 4-20 mA outputs are often ground referenced. But its's not the preferred way to pass the full loop current through the input amplifier. Many PLCs are simply using a 250 or 500 ohm shunt as passive I-V converter and no ampl
Information about the sensor seems scant. It is only normally required to trigger an alarm, not maintain it. As it is a self powered DC device I wonder if the sensing is done with DC rather than AC in which case electrolysis around the probe could be a problem, causing gas buildup which breaks the connection. If you have an oscilloscope it would be
One of my studend has made a board to drive stepper motors. The problem is that, the PC could not communicate with the PIC18F4550 in self power mode. We use the PICDEM FS USB framework (HID custom demo modified software The student has made a small board with an another PIC18F4550 in bus powered mode and it works. [/QUOT
In a self powered deviced, VBUS must no be shorted to VDD. There should be at least diodes to isolate the local power supply from VBUS. The USB standard requests, that VBUS isn't driven from the device side, also D+ and D- must not be driven before VBUS is present. The said VBUS monitoring circuit is used to enable the USB interface.
Sounds quite familiar for the FTDI chips (and possibly other device controllers). The host is stalling the device due to communication faults caused by electrical interferences. I guess, it should be possible to reconnect on the PC side, at least if the device driver supports it. As a workaround, a self-powered device interface would be always able
if your Kontiki is a sailing boat then you really want wind powered self steering gear as invented by "Blondie" Hasler. If you try to sail on a compass heading then if the wind shifts you could stop. Frank
Can you please try to explain which USB port type at which system you are talking about? Generally, you have host and device ports which have different roles regarding supply voltage. Also USB devices can be designed as bus-powered or self-powered.