For umbrella project I build my own power supply system.


- solar panel (3V, 80mA)

- storage/battery element (LiPo rechargeable battery from Fuel Tank BoosterPack)

- my own universal solar charger device (based on TI bq255040 )

- TI TLV70433 LDO (3,3V, 150mA)





Designed by my universal solar charger is based on TI bq25504









Solar charger parameters are configured by resistors.

-          battery over voltage protection value (ROV1, ROV2)

-          battery under voltage protection value (RUV1, RUV2)

-          battery ok value and battery ok hysteresis value (ROK1, ROK2, ROK3)

Maximum power point tracking value is set on 80%.

Battery thermal shutdown protection value is set on 65”C.


In my solution I configured values:

-          over voltage: 4,2V (ROV1=4,5 M ROV2=5,5 M)

-          under voltate: 2,8V (RUV1=4,5 M, RUV2= 5,5 M)

-          battery ok.: 3,3 V battery ok hysteresis 3,7V (ROK1= 3,4 M, ROK2= 5,5 M, ROK3= 1,1 M)

  Bq25504 working like on shematic below:


During choosing rezistors paremeters very  helpfull is TI spreadsheet:  bq25504_Design_Help_V1_2.ods I used it in my work.



In attachment I share

Bq25504 datasheet, bq25504_Design_Help_V1_2.ods spreadsheet, and TLV ldo datasheet


Lukasz, Poland