sparkfun ESP8266 - Electrical Characteristics and Ratings

Add an 850mAh LiPo and an LSM9DS0 9DoF IMU to the Thing, to create an IoT motion
sensor.
If both USB and LiPo are connected to the Thing, it’ll take power from the USB port and
charge the LiPo battery at up to 500mA.
Electrical Characteristics
The ESP8266’s maximum voltage is 3.6V, so the Thing has an onboard 3.3V regulator to
deliver a safe, consistent voltage to the IC. That means the ESP8266’s I/O pins also run at
3.3V, you’ll need to level shift any 5V signals running into the IC.
The input to this regulator can either be delivered by USB, LiPo battery, or through
the VIN pin.
Max Input Voltage: If you supply power to the board through the VIN, make sure the voltage
does not exceed 6V. That's the maximum input voltage of the AP2112K-3.3V regulator the
board uses.
Alternatively, if you have an external, regulated, supply you’d like to deliver directly to the
ESP8266, you can supply that voltage through the 3V3 pin (on the I2C header). While this
voltage doesn’t have to be 3.3V, it must be within the range of 1.7-3.6V.
Current Ratings
On average, the Thing pulls about 80mA. WiFi transmits and receives can momentarily
increase that draw. Here’s a table, transcribed from the ESP8266 datasheet, with some of the
more common current characteristics.
Parameter
Typica
l
Max Unit
Transmit 802.11b (1 Mbps) 215 mA
Transmit 802.11b (11 Mbps) 197 mA
Transmit 802.11g (54 Mbps) 145 mA
Transmit 802.11n 135 mA
Receive 802.11b 60 mA
Receive 802.11g 60 mA
Receive 802.11n 62 mA
Standby 0.9 mA
Deep Sleep 10 µA
Maximum I/O Pin Drive
Capability
12 mA
If your application requires maximum battery life, you’ll likely need to make liberal use of the
ESP8266’s deep sleep functionality. That’ll be covered later in this tutorial.