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Pololu-Romi-32U4-Carte-Alimentation (voir la source)
Version du 15 juin 2019 à 21:37
, 15 juin 2019 à 21:37→Régulateurs 5V et 3.3V
The Romi 32U4 Control Board also contains a 3.3 V LDO that draws its power from the output of the logic power selection circuit described below. The output of the 3.3 V regulator is designated '''3V3''' and is used to supply the on-board inertial sensors and level shifters.
The Romi 32U4 Control Board also contains a 3.3 V LDO that draws its power from the output of the logic power selection circuit described below. The output of the 3.3 V regulator is designated '''3V3''' and is used to supply the on-board inertial sensors and level shifters.
== Logic power selection ==
The Romi 32U4 Control Board’s power selection circuit uses the TPS2113A power multiplexer {{polpl|2596}} from Texas Instruments to choose whether its 5 V supply (designated '''5V''') is sourced from USB or the batteries via the 5 V regulator, enabling the control board to safely and seamlessly transition between them. The TPS2113A is configured to select regulated battery power (VREG) unless the regulator output falls below about 4.5 V. If this happens, it will select the higher of the two sources, which will typically be the USB 5 V bus voltage if the control board is connected to USB.
Consequently, when the Romi 32U4 Control Board is connected to a computer via USB, it will receive 5 V logic power even when the power switch is off. This can be useful if you want to upload or test a program without drawing power from the batteries and without operating the motors. It is safe to have USB connected and battery power switched on at the same time.
The currently selected source is indicated by the '''STAT''' pin; this pin is an open-drain output that is low if the external power source is selected and high-impedance if the USB supply is selected. The current limit of the TPS2113A is set to about 1.9 A nominally. For more information about the power multiplexer, see the [https://www.pololu.com/file/0J771/tps2113a.pdf fiche technique du TPS2113A] (1Mio pdf).
The 5 V output of the selection circuit is used to supply the control board’s ATmega32U4 microcontroller, logic power for the DRV8838 motor drivers, and the encoders; it also optionally powers an attached Raspberry Pi.
{{Pololu-Romi-32U4-TRAILER}}
{{Pololu-Romi-32U4-TRAILER}}