Description
This is an I2C programmable module that aims to cover the basic needs of battery powered microcontroller projects.
It has two programmable voltage outputs that can be adjusted/enabled/dis…
This is an I2C programmable module that aims to cover the basic needs of battery powered microcontroller projects.
It has two programmable voltage outputs that can be adjusted/enabled/disabled according to your application requirements.
To enable I2C communication between the two voltage domains, the board also has a level shifter integrated onto it.
The charger has extensive battery protection and monitoring features so you can deploy your device in a safe manner.
With the supercapacitor backed RTC it is ideal for solar powered sensor nodes that might not be able to keep a charged battery year-round but still need accurate timestamps.
Features Overview
Buck/Buck-Boost
Buck: 0.6-3.75V (1.8V default) current limit: 100-400mA
Buck-Boost: 1.8-5.5V (3.3V default) current limit: 100-800mA
1.1A max drain current from battery
Li-Po Charger
Battery protection
NTC temperature sensor (optional)
Compliant with JEITA charge temperature specification
Battery fuel gauge (battery capacity adjustment with aging/temperature)
RTC
High accuracy (±5ppm)
Two time-of-day alarms
Supercapacitor backup
I2C level shifter
Converts I2C clock and data lines between configured levels
Integrated 10 kOhm pull-up resistors
Enable/Disable pin (power saving)
Other features
Small footprint: 2x2 cm (0.8x0.8 in)
Castellated edges -> breadboard and PCB friendly
"Shipment mode"
Functional Description
Supply Voltage
To charge your battery the board needs to be supplied with 5V at the Vin pin. The device has a programmable (4.4-4.9 V) adaptive charge current limit to prevent the source from collapsing.
Level-Shifter Enable/Disable
To enable the level shifter The voltage on the EN pin should not be driven above V2.
If you do not need it or want to save power you can disable it by pulling EN to GND.
Shipment Mode
As the name implies this is the lowest power mode possible for this board and will turn off most function blocks. The RTC will be powered from the supercapacitor while in shipment mode.
To enter shipment mode you can set the EN_SHIPMODE bit via I2C. Alternatively you can connect a pushbutton between the *MR terminal of the board and GND. Press it for ~12s to enter shipment mode.
To exit shipment mode you can either press *MR again or by connecting a voltage source > 2.1 V to Vin.
NTC Thermistor
The charger supports 10k, 47k and 100k NTC thermistors (i.e. battery packs that already have one built in).
In case the thermistor is not wanted/needed the R2 resistor on the board is used to keep the charger happy. It is not possible to use an external thermistor while R2 is populated.
You can add a 100K NTC thermistor to your order. The B-Constant for these is 4303.
Caveats/Pitfalls
The charger and RTC are connected to the V1 side of the module.
The pull-up resistors of the level shifter are only active if the device is enabled
The connection to the positive terminal of the battery should be kept as short as possible otherwise the battery voltage readings might be off
It is not possible to use a NTC thermistor while R2 is populated
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