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Hardware Reference – energyShield 2 Pro

Hardware Overview

Pin Descriptions

Pin Name Description
5V 5V Out. Normally Connected. Can be disconnected by cutting “5V:5V” solder jumper.
Vin Normally disconnected. Vin can output 5V by soldering the “Vin:5V” solder jumper. This is needed for certain boards (pcDuino, Intel Galileo, ect.).Can be connected with 5V:Vin solder jumper.
3.3V 3.3V Out (Always connected)
GND Ground (Always connected)
SDA & SCL These pins are the I2C connections for the energyShild 2 Pro. I2C is used to communicate with the chips on the energyShied 2 Pro. They are normally connected to the UNO R3 I2C pins, but can be connected via solder jumper to A4 and A5 for older Arduinos.
A4 & A5 These pins are normally disconnected, but can be connected to SDA and SCL by soldering jumpers “SDA:A4” and “SCL:A5”. This allows for compatibility with older Arduinos.
A0 & A3 These pins are used to provide analog feedback of the voltage that is put on the barrel jack input. The voltage to this pin is scaled to 1/5 of it’s original voltage. The feedback voltage is normally connected to A0, but can be connected to A3 with the “VADP:A3” jumper.
RAW This pin provides unregulated power from the battery that does not switch off. It also has a higher maximum current than the regulated pins. It is useful for powering parts of a project that need power even when the shield is switched off (example, an LCD screen).
EN This pin allows the shield to be turned on without using the switch. Connecting this pin to the RAW pin will activate the power outputs while the switch is in the OFF position. (1 kΩ Input)
D3 & D7 These pins can be connected the alert pin on the RCT using the “RTC:D3” or “RTC:D7” jumpers.  This is not commonly used, but may be useful for some users who want to generate an interrupt on the Arduino, and not sleep the power.

All other pins on the energyShield 2 Pro are not connected. They serve as pass-throughs for the Arduino Headers.

Circuit Descriptions

Circuit Number/RefDes
(Noted with blue boxes)
1 / U101 USB Charger. This IC controls the USB charging of the LiPo battery. (AAT3693IDH-AA-T1)
2 / U201 5V Boost Switching Regulator (MIC2876-AYMT-T5)
3 / U202 3.3V Linear Regulator (TLV73333PDBVR)
4 / U701 I2C control circuitry to allow you to set the charging voltage setpoint for solar charging. (MCP4706A0T-E/CH)
5 / U501 This is a buck regulator for the barrel jack input. It is used for solar and adapter charging. This is capable of stepping down 7-23V to a voltage that the charge regulator can use. (RT8293BHGSP)
6 / U601 This IC is the fuel gauge. It tracks the amount of charge in the battery, along with the battery votlage and currect and reports it via I2C to the Arduino. (BQ27441DRZR-G1A)
7 / U801 This is the Real Time Clock. It allows the energyShield to maintain an accurate time reference, and if allows you to sleep the Arduino for very precise amounts of time. (PCF85063AT/AY)

Power Pin Specifications

Description Specification
USB Input Voltage 5V
USB Input Current 500mA Min
5V Output Current 1000mA Max
3.3V Output Current 300mA Max
RAW Pin Output Voltage 3V – 4.2V (Battery Voltage)
RAW Pin Output Current 1800mA Max (The 5V and 3.3V power regulators draw from this source as well.)

Logic Level Pin Specifications

Description Specification
EN (Enable Pin) Logic High Threshold (Enabled) 1.5V
EN (Enable Pin) Logic Low Threshold (Disabled) 0.4V
EN (Enable Pin) Voltage Tolerance 0 – RAW (Vbat)

I2C/TWI Specifications

Description Specification
10k Ohm Pull-up Voltage 5V
Fuel Gauge Slave Address 0x55
Real-time Clock Slave Address 0x51
Solar VMPP Control (DAC) Slave Address 0x60

Quiescent Power

State Current Consumption
Running 229 μA
Sleep 124 μA

The quiescent power is the amount of power consumed by the energyShield 2 Pro. While in sleep mode, the energyShield turns off the power regulators to disable power output. However, some of the circuitry on the energyShield is still running so that it can turn the power back on when the sleep is over. This self-power consumption, or quiescent power, during sleep is equal to 124 μA. That is 0.124 mA. To put that into perspective, the lithium polymer battery has a self-discharge rate of about 5% each month. For the 1800mA battery on the energyShield, that is equal to 125 μA. So, the amount of power consumed by the energyShield during sleep is the same order of magnitude as the power lost from a battery sitting on the shelf, doing nothing. Finally, a running Arduino Uno consumes nearly 50mA. Therefore, you save 99.75% of the power you would have used by sleeping the energyShield 2 Pro.

Power Flow Chart

This flow chart illustrates how power is handled in the energyShield 2 Pro.


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