Part Number:BQ25504
Hi,
I'like to design an energy harvesting shield for the adafruit feather boards (e.g. Feather M0 WIFI Board, www.adafruit.com/.../3010).
The schematics of the M0 WIFI Feather Board can be found here learn.adafruit.com/.../downloads.
I have the following questions regarding the BQ25504 energy harvesting IC:
1) What is the current consumption of the charger if the VBatt_UV < VBatt < VBatt_OV and VIN at the solar cell is 0V (e.g. at night time)?
2) Is there a way to completely shut down the IC at night time (Similar to the BQ25570 shipping mode)?
3) What is the best way to connect the BQ25504 with the Feather M0 WiFi Board?
Option 1:
Feather.VBatt -> BQ25504.VSTOR
Lipo Battery connected to BQ25504.VBATT
Advantages:
- Battery charge protection feature protects battery from discharging below UV limit / charging above OV limit
Disadvantages
- The Feather LDO draws up to 500mA, which results in 1V (2 Ohm * 0.5A) voltage drop on the PFET -> too high!
Option 2:
Feather.VBatt -> BQ25504.VBatt (Feather directly connected to LiPo-Battery)
Lipo Battery connected to BQ25504.VBATT
Advantages:
- There's no significant voltage drop if the Feather LDO draws 0.5A.
Disadvantages:
- The battery charge protection feature cannot protect the battery.
-> The VBAT_OK signal could be used to pull the Feathers EN signal low, if the battery voltages drops below a certain level.
Are my assumptions above correct?
Do you see better options to connect the two?
4) The Feather board also has a LiPo charger IC on board. Could charging the LiPo battery via Feather USB damage the BQ25504?
5) The datasheet states a peak current flowing from VIN into VIN_DC input of 200mA (0.5V < VIN < 3 V; VSTOR = 4.2 V). If I connect a power supply (3 Volt)
via 10 ohm resistor to the VIN, I only get a charge current of about 100mA. Is this correct?
6) Is there a way to increase the charge current to 200mA?