ESP32-S3 PowerFeather

Features & Specifications

Physical

• Board Dimensions: 65 mm L x 23 mm W x 7 mm H
• Feather-compatible format, Feather Wings support
• Board Features
  • USB-C connector
  • Two 2.5 mm mounting holes
  • Two 1x16 2.54 mm header pin holes
  • Thermistor pin hole
  • 2-pin JST PH Li-ion/LiPo battery connector
  • 4-pin JST SH STEMMA QT connector
  • Green user LED
  • Red charger status LED
  • User button
  • Reset button
  • On-board PCB antenna

Capabilities

Compute Resources

• 240 Mhz Dual-Core Xtensa LX7 Processor
• RISC-V / FSM Ultra Low Power Coprocessor
• 8 MB Quad-SPI Flash
• 2 MB Quad-SPI PSRAM
• 512 KB SRAM
• 16 KB RTC SRAM

Power Management

• Supply Monitoring
  • Current measurement
  • Voltage measurement
  • Good supply detection
• Supply Management
  • Set maintained supply voltage (can be used to set MPP voltage)
• Battery Monitoring
  • Voltage measurement
  • Temperature measurement
  • Current measurement (charge/discharge)
  • Charge estimation
  • Health & cycle count estimation
  • Time-to-empty and time-to-full estimation
  • Low charge, high/low voltage alarm
• Battery Management
  • Enable/disable charging
  • Set max charging current
• Others
  • 3V3 enable/disable
  • VSQT enable/disable
  • FeatherWing enable/disable via EN pin
  • Power States
    • Ship mode
    • Shutdown mode
    • Power cycle
  • Battery Protections
    • Undervoltage Detect @2.2 V, Release @2.4 V
    • Overvoltage Detect @4.37 V, Release @4.28 V
    • Overcurrent protection @3A
    • Trickle charging safety timer @1 hr
    • Temperature-based charging current reduction based on JEITA, cutoff at 0 °C and 50 °C.

Interfaces

Radio

• 2.4 GHz Wi-Fi 802.11b/g/n on PCB antenna
• Bluetooth 5 LE + Mesh on PCB antenna

Connectors

• USB 1.1 Full-Speed OTG on USB-C connector
• I2C on STEMMA QT connector

Pin Holes

• 23 I/O on the two 1x16 2.54 mm pitch header pin holes
  • All digital input and output capable
  • All UART, I2C, SPI, I2S, SDIO, PWM, CAN, RMT, Camera, LCD capable
  • 6 analog input capable
  • 5 touch input capable
  • 12 RTC capable (deep sleep pin hold, wake-up source)
• Semitec 103AT input on thermistor pin hole

Power

Input

• 5 V, 2 A max on VUSB USB-C connector
• 5 V - 18 V, 2A max on VDC header pin
• 4.2 V max, 2 A max on BATP and BATN JST PH Li-ion/LiPo battery connector

Output

• 3.3 V, 1 A max shared between board, 3V3 header pin and VSQT STEMMA QT connector
• 3.3 V - 4.2 V, 3 A max shared between board and VBAT header pin
• 5 V - 18 V, 2 A max shared between board and VS header pin

Current Consumption

Power State	BATP Current
Deep-Sleep, Fuel Gauge Enabled (Initial)	26 μA
Deep-Sleep, Fuel Gauge Enabled (Settled)	18.5 μA
Deep-Sleep, Fuel Gauge Disabled	18 μA
Ship Mode, Fuel Gauge Disabled	1.5 μA
Shutdown Mode, Fuel Gauge Disabled	1.4 μA

Pins & Signals

IO

These are signals routed to the ESP32-S3 GPIO pins.

Free IO

IO signals not connected to anything on-board; user code is free to configure and use these for any purpose within their respective GPIO capabilities. Note that the Description and Name are only for compatibility with the Feather specification, and does not strictly define the functionality of the IO. For example, there are other pins that can be used as analog inputs outside of A0 - A5, such as D8 which is ADC1_5. Another example is that IO other than MOSI, MISO and SCK can also be used for SPI - it's not limited to these ones.

Name	Description	Digital	Analog Input	RTC	Touch	JTAG
A0	Analog Input 0	GPIO10	ADC1_9	RTCIO10	TOUCH10
A1	Analog Input 1	GPIO9	ADC1_8	RTCIO9	TOUCH9
A2	Analog Input 2	GPIO8	ADC1_7	RTCIO8	TOUCH8
A3	Analog Input 3	GPIO3	ADC1_2	RTCIO3	TOUCH3
A4	Analog Input 4	GPIO2	ADC1_1	RTCIO2	TOUCH2
A5	Analog Input 5	GPIO1	ADC1_0	RTCIO1	TOUCH1
D5	Digital Input/Output 5	GPIO15	ADC2_4	RTCIO15
D6	Digital Input/Output 6	GPIO16	ADC2_5	RTCIO16
D7	Digital Input/Output 7	GPIO37
D8	Digital Input/Output 8	GPIO6	ADC1_5	RTCIO6	TOUCH6
D9	Digital Input/Output 9	GPIO17	ADC2_6	RTCIO17
D10	Digital Input/Output 10	GPIO18	ADC2_7	RTCIO18
D11	Digital Input/Output 11	GPIO45
D12	Digital Input/Output 12	GPIO12	ADC2_1	RTCIO12	TOUCH12
D13	Digital Input/Output 13	GPIO11	ADC2_0	RTCIO11	TOUCH11
MOSI	SPI MOSI	GPIO40				MTDO
MISO	SPI MISO	GPIO41				MTDI
SCK	SPI SCK	GPIO39				MTCK
RX	UART RX	GPIO42				MTMS
TX	UART TX	GPIO44
TX0	Serial Log Output	GPIO43
SCL	I2C SCL	GPIO36
SDA	I2C SDA	GPIO35

Capabilities

• Digital - IO that can output or accept input of 3.3 V digital logic; supports UART, I2C, SPI, I2S, SDIO, PWM, CAN, RMT, Camera, and LCD peripheral.
• RTC - IO that can hold output state during deep-sleep; or be used as a wake-up source from deep-sleep.
• Touch - IO that can be used as capacitive touch input.
• Analog Input - IO that can read analog signals; X, Y in ADCX_Y denotes the ADC number and channel respectively.
• JTAG - IO that can be used for JTAG debugging.

User-Managed Fixed IO

IO signals connected to a component on-board, limiting its use. For example, it does not make sense to use BTN as UART TX due to being connected to a button, even though it is technically capable of doing so. User code is still in control in terms of configuring and using these IO.

Pin	Description	Digital	RTC
ALARM	Battery Fuel Gauge Alarm Input	GPIO21	RTCIO21
INT	Battery Charger Interrupt Input	GPIO5	RTCIO5
BTN	User Button Input	GPIO0	RTCIO0
LED	Green User LED Output	GPIO46	RTCIO7

SDK-Managed Fixed IO

IO signals connected to a component on-board, whose configuration and use is managed by the SDK. User code should not configure and use these IO, as doing so can cause faulty behavior.

Pin	Description
USB_DP	USB Data Positive
USB_DM	USB Data Negative
PG	Power Supply Good Indicator Input
3V3_EN	3V3 Enable Output
VSQT_EN	VSQT Enable Output
EN0	Board Enable Output
SCL1	STEMMA QT I2C SCL
SDA1	STEMMA QT I2C SDA

Special Function

Signals not routed to the ESP32-S3 GPIO pins, or are routed to other integrated circuits on-board such as the battery charger and fuel gauge.

Name	Description
CHG	Battery Charger Status LED
RST	ESP32-S3 Module Reset
QON	Ship Mode Exit
TS	Semitec 103AT Thermistor Input
EN	Feather Wing Enable Output

Power Input

Supplies power to the board.

Name	Description
BATN	Li-ion/LiPo Negative Terminal
BATP	Li-ion/LiPo Positive Terminal
VUSB	5V USB Power Input
VDC	3.8 V - 18 V Header Pin Input

Power Output

Powers loads connected to the board. Please don't connect power supplies to these.

Name	Description
VBAT	3.7 V - 4.2 V Battery Output
VS	3.8 V - 18 V Supply Voltage; Higher of VDC and VUSB
3V3	Header Pin 3.3 V Output
VSQT	STEMMA QT 3.3 V Output

Ground

0 V reference for the components on-board, input power supplies and connected loads.

Name	Description
GND	Ground Pin

Notes

Feather Differences

While ESP32-S3 PowerFeather is largely compatible with the Adafruit Feather ecosystem, it has has a few deviations from the Feather specification.

• EN Behavior

  On standard Feather boards, the EN pin is connected to the enable pin of the on-board 3.3 V regulator. Pulling EN low means disabling the 3.3 V regulator and everything powered from it.

  On PowerFeather, EN is connected to an ESP32-S3 IO pin. User code can read the state of this pin and act accordingly, i.e. it can disable the 3V3 and VSQT load switches and put itself to deep-sleep to emulate behavior on standard boards; or it might do something completely different.

  Furthermore, the ESP32-S3 itself can pull EN low if user code needs to disable connected Feather Wings.

• QON Pull-Up

  QON replaces AREF on ESP32-S3 PowerFeather, and is normally pulled high up to 5 V. Make sure when connecting Feather Wings that it is able to handle this voltage on its AREF pin, or the Feather Wing does not use AREF at all.

  If this is an issue, QON can be removed by breaking a solder bridge labeled B2.

• VS Up to 18 V

  On standard Feather boards, the pin at the same position as VS is the 5 V output (there is no on-board 5 V regulator, the 5 V comes from the USB supply). On PowerFeather, VS outputs either VUSB or VDC, whichever has a higher voltage. Since VDC can be up to 18 V, this means that VS can also be up to 18 V.

  Keep this in mind if using a power supply with voltage higher than 5 V on VDC, as it might destroy Feather Wings that only expects 5 V on its VS/5V pin.

Soldering Headers

Due to the ESP32-S3 module's size, some of the header holes are awfully close its pads. This means that in these areas, there is a risk of shorting a hole with a pad when soldering headers.

This is especially dangerous with VDC, since it is a high voltage power input (up to 18 V) that would most likely fry the ESP32-S3 if it comes in contact with one of its pads. It would be wise to check for shorts using a multimeter after soldering headers, just to be safe.

Battery Polarity

The wiring polarity for batteries with JST-PH connectors is not standardized. Please make sure the batteries you use are wired with the correct polarity - it is printed on the silkscreen!

Miscelleanous Questions

• Can VUSB and VDC be plugged in at the same time?

  VUSB and VDC are or'ed with schottky diodes, so it's safe to have them plugged in at the same time. The schottky diodes ensure that current does not flow from VDC to VUSB or vice versa depending on which is higher. The higher voltage of the two supplies PowerFeather; if they are around the same voltage, they share the current load for PowerFeather and all connected devices.

• Can power be drawn by the board or connected loads while charging?

  PowerFeather uses a charger IC that implements a power path, so it is safe to have PowerFeather and connected devices draw power while charging the battery. Furthermore, the power path allows the battery to supplement VUSB or VDC during load power spikes to prevent brownouts. Also, if there is VDC or VUSB, but there is no battery or the battery is fully depleted, VBAT is still regulated to 3.7 V.

• Does ESP32-S3 PowerFeather support LiFePO4/LFP?

  The board as a whole does not support LiFePO4 batteries. While the charger IC supports LiFePO4, the fuel gauge IC does not. Furthermore, PowerFeather uses a linear regulator to provide the 3.3 V power rail, which won't function properly under a LiFePO4 battery with nominal voltage of 3.2 V.

• What do you mean by near/pseudo-MPPT?

  PowerFeather does not support 'true' MPPT in the sense that it does not do full tracking of the panel's I-V curve. However, the panel MPP voltage can be set, and the charger IC will dynamically regulate charging current to prevent the panel voltage from collapsing below it. This provides near/pseudo-MPPT performance, since the MPP voltage for a typical panel remains roughly the same across various illumination levels.

  For more details, please read this Adafruit design note for one of their solar chargers that uses the same dynamic charging current regulation technology. However, the advantage of PowerFeather compared to their solar charger is that their solar charger has a fixed MPP voltage at 4.5 V, while for PowerFeather it can be adjusted in firmware up to 16.8 V.

Appendix

Current Measurements

These are measurements for the figures in Current Consumption. These were measured using Nordic Power Profiler Kit II (a.k.a PPK2) acting as a battery @3.7 V plugged into BATP and BATN; and with no external supply (VBUS or VDC).

Deep Sleep, Fuel Gauge Enabled (Initial)	Deep Sleep, Fuel Gauge Enabled (Settled)
The fuel gauge initially samples around every ~1 s, with each sample registering a current spike to up ~5 mA.	The fuel gauge samples settles down to around every ~2 s, with each sample registering a current spike up to ~50 μA.

Deep Sleep, Fuel Gauge Disabled	Ship Mode, Fuel Gauge Disabled	Shutdown Mode, Fuel Gauge Disabled

You can download the raw traces obtained from PPK2 using the links below, and open them with your nRF Connect Power Profiler Software.

• Current measurement trace for deep sleep with fuel gauge enabled - initial and settled
• Current measurement trace for deep dleep with duel gauge gisabled, ship mode and shutdown mode

Key Components

Component	Manufacturer	Part	Datasheet
Microcontroller & WiFi + Bluetooth LE SoC	Espressif	ESP32-S3-WROOM-1	https://www.espressif.com/sites/default/files/documentation/esp32-s3-wroom-1_wroom-1u_datasheet_en.pdf
Battery Charger	Texas Instruments	BQ25628E	https://www.ti.com/lit/ds/symlink/bq25628e.pdf?ts=1712390973163&ref_url=https%253A%252F%252Fwww.google.com%252F
Battery Fuel Gauge	Onsemi	LC709204F	https://www.onsemi.com/pdf/datasheet/lc709204f-d.pdf
3.3 V Regulator	Torex	XC6220	https://product.torexsemi.com/system/files/series/xc6220.pdf

Photos