The power supply for the test fixture is a cheap unregulated 15-volt AC-DC wall-wart. The program can do a sweep over ranges of voltage and current and report the results in a table. Then I use the Mega's analog inputs to read the DUT's input current and output voltage. I have some breadboard analog electronics to supply an input voltage and an output sink current to the device-under-test (DUT) under control of filtered PWM outputs from the Mega. Here is a picture of the latest setup: This fixture uses an Arduino Mega as a controller, only because my Arduino UNO was fried. It took some time to put together a stable and well-calibrated automatic measuring rig. Read more »Īs promised, I made a series of measurements to evaluate the efficiency of the Buck-Boost (TPS63070) FeatherWing. This is not connected by default, but soldering. However, there is a power-saving mode that in enabled with a pin this is the default of this design, but it can be overridden (PWM mode selected) by soldering across jumper pads JP4.Ī resistor divider is provided for monitoring the input voltage. Low Power Mode: the converter is designed to be highly efficient, but in its standard PWM mode, the efficiency is optimized for a high-current regime. The unused source is disabled at the same time. Due to the design of the Feather, this pin is also powered by the LDO regulator on the main board in order to avoid having competing current sources, a SPDT slide switch is provided, by which the user selects which source is to supply the 3.3V. The 3.3-V output from the converter is fed to the 3.3V pin to supply the Feather and any Wings in the stack. It should not interfere with the function of any of the digital or analog pins. This board shares the Feather pinout and, depending on the headers installed, can be stacked above or below the Feather board and any optional wings. The typical user will need much less than this. The TPS63070 is specified to output up to 2A due to the current capability of the pins, however, no more than 500mA is recommended. In this way, a battery can be almost completely drained before discarding. The TPS63070 switching converter can start operation at any input voltage from 3V to 15V once started, the TPS63070 will continue to run down to 2V if the supply is not interrupted. Slide switch to select switcher or LDO operation unused regulator disabled.
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