Datasheet

PIN35 ADC_VREF
PIN33 AGND
PIN30 RUN
VBUS is the micro-USB input voltage, connected to micro-USB port pin 1. This is nominally 5V (or 0V if the USB is not
connected or not powered).
VSYS is the main system input voltage, which can vary in the allowed range 1.8V to 5.5V, and is used by the on-board
SMPS to generate the 3.3V for the RP2040 and its GPIO.
3V3_EN connects to the on-board SMPS enable pin, and is pulled high (to VSYS) via a 100kΩ resistor. To disable the
3.3V (which also de-powers the RP2040), short this pin low.
3V3 is the main 3.3V supply to RP2040 and its I/O, generated by the on-board SMPS. This pin can be used to power
external circuitry (maximum output current will depend on RP2040 load and VSYS voltage; it is recommended to keep
the load on this pin under 300mA).
ADC_VREF is the ADC power supply (and reference) voltage, and is generated on Pico W by filtering the 3.3V supply.
This pin can be used with an external reference if better ADC performance is required.
AGND is the ground reference for GPIO26-29. There is a separate analogue ground plane running under these signals
and terminating at this pin. If the ADC is not used or ADC performance is not critical, this pin can be connected to digital
ground.
RUN is the RP2040 enable pin, and has an internal (on-chip) pull-up resistor to 3.3V of about ~50kΩ. To reset RP2040,
short this pin low.
Finally, there are also six test points (TP1-TP6), which can be accessed if required, for example if using as a surface-
mount module. These are:
TP1 Ground (close-coupled ground for differential USB signals)
TP2 USB DM
TP3 USB DP
TP4 WL_GPIO1/SMPS PS pin (do not use)
TP5 WL_GPIO0/LED (not recommended to be used)
TP6 BOOTSEL
TP1, TP2 and TP3 can be used to access USB signals instead of using the micro-USB port. TP6 can be used to drive the
system into mass-storage USB programming mode (by shorting it low at power-up). Note that TP4 is not intended to be
used externally, and TP5 is not really recommended to be used as it will only swing from 0V to the LED forward voltage
(and hence can only really be used as an output with special care).
2.2. Surface-mount footprint
The following footprint (Figure 5) is recommended for systems which will be reflow-soldering Pico W units as modules.
Raspberry Pi Pico W Datasheet
2.2. Surface-mount footprint 9