diff --git a/accessories/making-accessories.md b/accessories/making-accessories.md index e4b6bba..1fa2227 100644 --- a/accessories/making-accessories.md +++ b/accessories/making-accessories.md @@ -29,17 +29,19 @@ The edge connector on the V2 board revision is backwards ## Battery Pads -There are two lozenge shaped pads on the back of the micro:bit. These allow you to connect a battery holder via a mechanism other than the JST connector. +There are two rounded rectangular pads on the back of the micro:bit. These allow you to connect a battery holder via a mechanism other than the JST connector. -![Picture of the two lozenges](/docs/accessories/assets/making-accessories-d7c25.png) +![Picture of the two rounded rectangular pads](/docs/accessories/assets/making-accessories-d7c25.png) + +The upper pad is 0V or GND and the lower pad is 3V. ### V2 revision -In the V2 board revision, the 3V lozenge is connected to the 3V ring on the edge connector. +In the V2 board revision, the 3V rounded rectangular pad is connected to the 3V ring on the edge connector. -- If you make an accessory that uses the lozenges, it must be protected from reverse charging when the board is powered by USB, battery or edge connector. -- You can now source power from the lozenges if you are making an accessory, as they are consistent with the power architecture of the edge connector. +- If you make an accessory that uses the rounded rectangular pads, it must be protected from reverse charging when the board is powered by USB, battery or edge connector. +- You can now source power from the rounded rectangular pads if you are making an accessory, as they are consistent with the power architecture of the edge connector. -Due to the addition of a speaker, current accessories that use the lozenges to power the micro:bit will no longer fit. +Due to the addition of a speaker, current accessories that use the rounded rectangular pads to power the micro:bit will no longer fit. diff --git a/hardware/powersupply.md b/hardware/powersupply.md index eb1986f..12cbcdc 100644 --- a/hardware/powersupply.md +++ b/hardware/powersupply.md @@ -16,7 +16,7 @@ Power to the micro:bit may be provided via: - USB connection via the interface chip (which has an on-board regulator) - A battery plugged into the JST connector. - The 3V and GND pins on the Edge Connector -- The two lozenge shaped pads on the rear right of the board +- The two [rounded rectangular pads](/docs/accessories/assets/making-accessories-d7c25.png) on the rear right of the board Power from the micro:bit can be provided by the 3V and GND pins to small external circuits. @@ -83,9 +83,13 @@ There is further information about the [battery connection and use](https://supp ### 3V Ring Powering The micro:bit may be powered from the 3V/GND rings on the edge connector. -There are also two lozenge shaped pads on the far right of the back of the PCB that can be used to supply power (e.g. solderable pads for a 2xAAA holder that has wires or pins at one edge). [The topmost lozenge is 0V and the bottom most lozenge is 3V](../../accessories/making-accessories/#battery-pads). +There are also two [rounded rectangular pads](/docs/accessories/assets/making-accessories-d7c25.png) on the far right of the back of the PCB that can be used to supply power (e.g. solderable pads for a 2xAAA holder that has wires or pins at one edge). -When powering from the 3V ring or the lozenge on the PCB, you should take appropriate best practice precautions: +![Picture of the two rounded rectangular pads](/docs/accessories/assets/making-accessories-d7c25.png) + +The upper pad is 0V or GND and the lower pad is 3V. + +When powering from the 3V ring or the rounded rectangular pads on the PCB, you should take appropriate best practice precautions: 1. Fit an external protection diode (preferably with a low Vf rating) to prevent damage due to the power supply being connected the wrong way round. @@ -95,7 +99,7 @@ When powering from the 3V ring or the lozenge on the PCB, you should take approp The [schematic](/hardware/schematic/) shows the architecture of the power supply. Key points to note are that there are two BAT60A diodes, one from the 3.3V supply from the KL26/27 interface chip, and one from the external battery connector. -Note that the 3V ring on the edge connector is V_TGT, which is the raw supply provided to all on-board chips, so this is why extra care should be taken when connecting directly to the 3V ring or the 3V lozenge. +Note that the 3V ring on the edge connector is V_TGT, which is the raw supply provided to all on-board chips, so this is why extra care should be taken when connecting directly to the 3V ring or the 3V [rounded rectangular pad](/docs/accessories/assets/making-accessories-d7c25.png). The BAT60A devices have a low Vf rating, you can read about this in the [BAT60A datasheet](http://www.infineon.com/dgdl/Infineon-BAT60ASERIES-DS-v01_01-en.pdf?fileId=db3a304313d846880113def70c9304a9) diff --git a/latest-revision/latest-revision-accessories.md b/latest-revision/latest-revision-accessories.md index f2389c8..daab2d6 100644 --- a/latest-revision/latest-revision-accessories.md +++ b/latest-revision/latest-revision-accessories.md @@ -82,9 +82,11 @@ Whereas on previous revisions, the I2C bus was shared between the motion sensor ### Power -The micro:bit can now be powered from the two lozenge shaped pads on the rear of the board and the 3V/GND pins. +The micro:bit can now be powered from the two rounded rectangular pads on the rear of the board and the 3V/GND pins. -If you use the lozenge pads, you must diode (or otherwise) protect themselves from the micro:bit having power via another source. This was still necessary on the previous revision when the board was powered from battery, but is now true for USB and edge-connector power also. +![Picture of the two rounded rectangular pads](/docs/accessories/assets/making-accessories-d7c25.png) + +If you use the rounded rectangular pads, you must diode (or otherwise) protect themselves from the micro:bit having power via another source. This was still necessary on the previous revision when the board was powered from battery, but is now true for USB and edge-connector power also. The nRF52 supplies 300mA to drive the board. 110mA is reserved for powering on-board components. **190mA** is then available for accessories.