pimoroni Pi Stemma QT Breakout for Raspberry Pi and Compatibles

Part & documents

Source	shop.pimoroni.com/products/adafruit-pi-stemma-qt-breakout-for-raspberry-pi-and-compatibles →

Specs

MCU	none (passive adapter; AP2112K-3.3 LDO, green power LED, two 10K pull-ups)

Pinout

10 pads, as the vendor numbers them.

#	Name	Function	Signals
1	3V3 (NC)	2x3 header pad 1, the Pi's 3V3 pin: the fab file gives it no net at all - it is deliberately left unconnected, because the board makes its own 3.3 V from the 5 V rail.	Raspberry Pi 3.3 V pin, not connected
2	5V	2x3 header pad 2, the Pi's 5 V pin: feeds the AP2112K-3.3 regulator.	power in
3	SDA	2x3 header pad 3, the Pi's GPIO2 (SDA1): through to QT socket pad 9.	I2C data
4	5V	2x3 header pad 4, the Pi's second 5 V pin: the second 5 V feed into the regulator.	power in
5	SCL	2x3 header pad 5, the Pi's GPIO3 (SCL1): through to QT socket pad 10.	I2C clock
6	GND	2x3 header pad 6, the Pi's ground pin: common ground for power and logic.	ground
7	GND	QT socket pad 1 (connector's own numbering): ground, the first pin of a STEMMA QT / Qwiic cable.	ground
8	3V3	QT socket pad 2: the AP2112K's 3.3 V output, not the Pi's 3.3 V rail.	regulated 3.3 V out
9	SDA	QT socket pad 3: I2C data, pulled up to the local 3.3 V by a 10K resistor, tied to the header's GPIO2 pad.	I2C data
10	SCL	QT socket pad 4: I2C clock, pulled up to the local 3.3 V by a 10K resistor, tied to the header's GPIO3 pad.	I2C clock

Buses

Bus	Signals	Pins	Voltage	Note
I2C ×1	SDA, SCL	9 (QT pad 3, Pi GPIO2), 10 (QT pad 4, Pi GPIO3)	3.3 V V	One I2C bus on the Pi's default port. Two 10K pull-ups to the board's own 3.3 V are fitted, so an add-on does not need its own; leave them on the add-on fitted too and the parallel value only drops to 5K, which is still legal.

Power

Input	5 V from the Pi header pins 2 and 4

The Pi's 3V3 pin is not connected on this board by design.

Outputs

Rail	Rating	Note
3.3V	3.3 V V	AP2112K-3.3 (U2) output, offered on QT socket pad 8; 10 uF in, 10 uF out, 0.1 uF bypass.

Notes

Pimoroni is the reseller: the board is Adafruit 6365, and `purpose` is Pimoroni's own product title with the Adafruit prefix removed. `pins` numbers the 2x3 header 1-6 (fab file element RPI1, package RASPBERRYPI_2X3_THMSMTTOP) and offsets the QT socket to 7-10 so the two connectors' own 1-4 numbering cannot collide - the VS1053 convention. Labels are the fab file's nets on each pad, because Adafruit prints the silk as PLABEL stroke artwork with no text nodes and its learn page names the connections in prose only; pad 1 has no net in the file and is labelled as unconnected rather than given a guessed function. The board carries no headline chip, so `part` is null and there is no per-part data sheet to link - the regulator's own document is not this board's data sheet.

AI context

Dense context for pasting into a model prompt — addresses, pinout, voltages, tolerances and the vendor's reference circuit.

BOARD: Adafruit 6365, a 15.2 x 15.0 x 5.5 mm (1.1 g) adapter that puts a 4-pin JST SH STEMMA QT / Qwiic socket on a Raspberry Pi 40-pin header with no soldering. It carries no IC of its own - a 2x3 socket at the top edge, one JST SH 4-pin connector at the bottom edge, a 3.3 V regulator, a green power LED and two 10K pull-ups. Resold by Pimoroni; the maker is Adafruit.
ADDRESSES: none. The board holds no I2C device, so a scan finds only what is plugged into the QT socket. Its SDA and SCL are wired to the Pi's default I2C port, GPIO2 (physical pin 3) and GPIO3 (physical pin 5), and the learn guide states the same pair.
PINOUT: 10 pads, two connectors each numbered from 1 by the vendor, so the QT socket is offset by the 2x3 header's six pads and the offset is stated here. 2x3 header (fab file element RPI1, package RASPBERRYPI_2X3): 1 lands on the Pi's 3V3 pin and is NOT CONNECTED on this board; 2 = 5V; 3 = SDA (GPIO2); 4 = 5V; 5 = SCL (GPIO3); 6 = GND. The same six land again on the 2' side as castellated duplicates of 1-6. QT socket (element CONN3, JST_SH4): 7 = GND, 8 = 3.3V, 9 = SDA, 10 = SCL - the standard STEMMA QT / Qwiic pin order.
SUPPLY: the header's 5 V pins (2 and 4) feed an AP2112K-3.3 LDO (U2) with a 10 uF input capacitor (C2), a 10 uF output capacitor (C3) and a 0.1 uF bypass (C1); the regulator's 3.3 V is what the QT socket offers. The Pi's own 3.3 V rail is not used at all.
LOGIC LEVEL: 3.3 V on the QT socket, produced locally, so the socket does not care what the host drives. Nothing on the board is 5 V tolerant on behalf of a peripheral: the 3.3 V is the regulator's, and a 5 V sensor chained onto the QT socket would see 3.3 V logic.
REFERENCE CIRCUIT: two 10K resistors in the fitted 4-element 10K pack (R3) pull SDA and SCL up to the regulator's 3.3 V, so an add-on can leave its own pull-ups off - the vendor added them specifically because some Pi-compatible boards ship without any. A green LED (D1) shows the regulator is up; solder jumper SJ1 on the back, outlined in white on the silk, cuts its power.
TRAPS: the 2x3 socket covers only the first six pins of the 2x20 header, and pad 1 of it - the Pi's 3V3 pin - is deliberately left unconnected, so the QT socket's 3.3 V comes from the onboard regulator and never from the Pi's rail; powering the board from a host whose 3V3 pin is its only 3.3 V source will still work (the 5 V pins do the work) but the Pi's 3.3 V rail is not bridged to the QT socket. Cutting SJ1 does not disconnect the 3.3 V rail, only the LED. It is a removable socket, not a soldered HAT: it will pull off, so it cannot be relied on in a moving assembly.

Provenance

Every figure on this page was read from the 3 sources below and last checked on Oct 28, 2026.