BQ24650: Setting charge voltage with a microcontroller

Jesse van der Zouw

Expert 1045 points

Part Number: BQ24650

Is it possible to set the charge voltage of the BQ24650 with a microcontroller instead of a voltage divider?

I was thinking of something like a DAC output feeding into the Vfb pin, but I do not know how that would work exactly.

Does somebody have an idea?

over 6 years ago

0 Kedar Manishankar over 6 years ago

TI__Mastermind 24075 points

Hi Jesse,
What are your system requirements? BQ24650 is a standalone charger, and if using a microcontroller, then you can also take a look at the I2C host controlled chargers in our portfolio. Is there a specific reason why you need to control charge voltage with microcontroller?

0 Jesse van der Zouw over 6 years ago in reply to Kedar Manishankar

Expert 1045 points

I would like to charge 3-5S lithium-ion packs. Is there an IC that can handle that?

0 Kedar Manishankar over 6 years ago in reply to Jesse van der Zouw

TI__Mastermind 24075 points

Hi Jesse,
For 5s application, BQ246xx family would be required to support the charge regulation voltage. Is your application for removable battery packs that can sometimes be 3s, 4s and 5s? MCU can be used to control FET that can change the resistor divider at VFB, thereby changing the charge regulation voltage. For 3s, 4s, 5s you can have 2 different parallel combination of resistors driven by the MCU which will change the VFB equation according to what s battery you wish to have, setting the correct charge voltage. Does this summarize your application?

0 Jesse van der Zouw over 6 years ago in reply to Kedar Manishankar

Expert 1045 points

I have designed a universal BMS for 3/4/5S li-ion and LiFe packs, but currently configuration is set by a jumper. For an updated version I am exploring options to have all settings be managed by a microcontroller.

The multiple resistor/FET option is not as simple as I would like it, but should work fine. Thanks for your help.

0 Kedar Manishankar over 6 years ago in reply to Jesse van der Zouw

TI__Mastermind 24075 points

Hi Jesse,
For resistor options you can use the BQstroller calculation tool under software at this link: www.ti.com/.../toolssoftware
Glad to be of help. If further questions arise, feel free to open a new thread.

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BQ24650: Setting charge voltage with a microcontroller