• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 63 subscribers
  • Views 676 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ24072T: bq24072T and bq24072 Question about the Vout (REG)

MohammedAl-Amin
Intellectual 540 points
Part Number: BQ24072T
Other Parts Discussed in Thread: BQ24072, , BQ24040

Hello,

Looking at the bq24072T or bq24072, it mentions that the Vout is regulated at Vbat+225mV. The problem is I have a microchip which can only be safely be used between 2.8V to 4.3V. 

The thing is I have two types of batteries (3300mAH 3.6V with float voltage of 4.2V and 2600mAH 3.7V with float voltage of 4.2V).

My question is if my battery is charging and reaches full charge that would be 4.2V but the Vout (reg)  would regulate is at 4.2V + 225mV (4.425V).

Am I correct in saying that Vout would reach 4.425V when the battery is at full capacity? Or would the peak Vout be less?

I hope to hear from you guys soon.

Best regards

Mohammed Al-Amin

  • 0
    TI__Guru 67476 points
    You are correct, for the bq24072T or 72 voltage at OUT pin will be up to 4.425V (4.2V + .225V). If your max voltage on the microchip s 4.3V this would not work.
    Some options to consider:
    1.) Add a diode in series with the microchip to reduce the voltage from out. The regulation may not be good enough.
    2.) Add LDO to reduce voltage to the microchip. This will provide better regulation.
    3.) Connect the microchip directly to the battery. A switch ckt may be needed to disconnect load during off time.
    4.) If the load is connected directly to the battery take a look at the bq24040, it is designed to support this configuration.
  • 0 in reply to Bill Johns
    Intellectual 540 points
    Thats Great thank you, I have gone ahead and implemented a dual diode, (two inputs one output) using BAT54CW, with VOUT and 3.3V buck/boost which I have on the board, to keep the MCU live if VOUT goes too low due to the voltage drop of the BAT54CW.