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Part Number: BQ24266
Hi, I am using BQ24266 after recommendation from Michael from TI asia team for my requirement for personal/vehicle tracker VALTRACK-V2 gps tracker application to support vehicle input voltage of 12V and supply load and charge internal battery at a time. The design is ready and PCB is assembled and charger is working but the output voltage on SW pin goes from 4.2 to 4.28 volts when charger is connected . 4.3V is the maximum voltage the SIM800 GSM module can take. And it starts giving over voltage warning and gets warm. Even the BQ24266 is getting hot when charging.
Is there any way i can limit the voltage to 4.0V at output ?
How can i calculate the charge current. I am not able to understand the Kieset value mentioned in datasheet. ?
Can BQ24266 run fine in long term inside vehicle supplying power to load and keeping battery charged for emergency purposes. ?
Is this heat normal when running at 12V input, Do i need a heat sink?
The Inductor parts recommended in EVM datasheet were out of stock so i chose this inductor, Please check if its suitable.
I have tried chaning the IUSB lines to all possible combinations but the BQ24266 keeps getting hot.
The PCB is a 6 layer board and its cramped up.
Attaching the schematic and the PCB images of front and bottom for reference
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In reply to Jeff F:
Thank you for the quick response. :)
I will increase the capacitance value on DRV, No problem.
I could add a linear regulator but which part would you recommend for reducing 4.2V to 4V on VSYS while keeping the current >2A.
Right now i am measuring voltage at VSYS to be 4.31V at 12V when charger is connected.
The heating is happening at 5V and 12V as well. The heat generated is almost same at both voltage inputs. The power pad is connected with 2 vias to ground plane. The ground is poured on all layers with in addition to separate ground plane layer. The ground planes are shared by all devices including GSM module which also generates a mild amount of heat, but not more. Do you think it will saturate the ground plane? Any remedies for this?
The typical value of KIESET will help, Thanks for that. So my input current is set to 3A right now because of 400 Ohms being used. ?
I have I2C available on board, Are you saying that i can adjust the voltage that comes at VSYS which is provided to the system or the max voltage that the battery is charged to? I want reduction in the VSYS voltage in my schematic and want the battery to be fully charged?
Is this chip BQ24261M fully pin compatible to my current part BQ24266? can i use it as drop in replacement?
Also why there are two separate charge current limit settings, ISET and IUSB lines. How different are these? Dont they both limit the input charge current drawn from source? Please clarify.
In reply to Ravi Pujar1:
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