Standard Use - Semtech TSWITX-G4-EVM User Manual

Standard Use

The TSWITX-G4-EVM is easy to set up and use. Connect a USB cable from any USB port capable of
driving up to 2 watts (most PCs will suffice) to the USB port on the EVM. On application of power, the
green LED should light, indicating the board is now active.
At this point, the EVM is ready to transmit power. A few times each second, the transmitter emits a 'ping'
of energy in search of a compliant receiver in range.
When in range, the receiver is powered by the ping sufficiently to be able to announce its presence to the
transmitter, and a transaction begins. The transmitter provides a small amount of power to the newly
discovered receiver, so it can tell the transmitter what its power requirements are.
At the completion of this handshake, the transmitter begins providing the requested power. During power
transfer, the receiver continuously communicates with the transmitter, actively directing the process. In
this way, it is assured that power is only sent when and how it is required by an available and desirous
receiver – and in the way that is compatible with the requirements of the receiver. If required, a receiver
can actively increase or decrease its power request, and the transmitter will act accordingly. As such,
equipment with complex charging requirements can be precisely supported and only the desired amount
of power is provided.
EVM Receiver Tests
A variety of tests can be performed with the use of the TSWIRX-5V2-EVM receiver module.
In order to use the TSWIRX-5V2-EVM as a target receiver, simply place the receiver over the target circle
on the transmitter EVM module. There will be 5V output on RX output.
The optimal load to select would be a Programmable DC Electronic Load. A 'load box' can easily be set
to draw a selected current or power at the turn of a knob, making them very flexible and easy to use in
observing power supply operation in general. If a load box is not available, a power resistor decade box is
nearly as convenient, as it can easily be set to any desired resistance to simulate a range of load
conditions. If need be, a selection of resistors could be used as test loads, though without the ease of
modification of the prior options. Be sure the test load is rated for at least the amount of power being
tested. Finally, any device that uses a 1.25W power can be used as a test load should that be desired.
Whatever load is selected, wires must be run from the VOUT+ and GND pins of the receiver EVM to the
selected test load, as per the following illustration. Once the load is added, the receiver EVM can be used
to perform a variety of tests.
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TSWITX-G4-EVM 4 of 18
User Guide Rev 1.00