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BQ24030-Q1: BQ24030-Q1/BQ24031-Q1 output voltage

Svenja G.
Prodigy 40 points
Part Number: BQ24030-Q1
Other Parts Discussed in Thread: BQ24031-Q1, TPS62290

Hello,

i want to use the IC BQ24030-Q1 or BQ24031-Q1 to charge a 3.7 V Lithium-Polymer battery. 

In order to be able to power my system, I need an output voltage of 3.3 V.

From the data sheet, I could read that the LDO provides an output voltage of 3.3 V when AC or USB is present. However, my system should not be operated when the LiPo battery is being charged via AC or USB.

So what output voltage does the IC deliver (on the output Pin OUT) when the LiPo battery is used as the primary source? Do I also need a step-up or step-down converter to generate the 3.3 V to power my system?

Thanks for your help!

  • 0
    TI__Mastermind 23410 points

    Hi Svenja,

    Svenja G. said:
    So what output voltage does the IC deliver (on the output Pin OUT) when the LiPo battery is used as the primary source?

    The output tracks the battery voltage when the device is only being powered by the battery (no USB power or AC power is present). If the output voltage falls below 200mV of the battery, a short is declared and the output voltage will be turned off. 

    Svenja G. said:
    Do I also need a step-up or step-down converter to generate the 3.3 V to power my system?

    Yes, you will still need a converter to generate the 3.3V. 

    Svenja G. said:
    From the data sheet, I could read that the LDO provides an output voltage of 3.3 V when AC or USB is present. However, my system should not be operated when the LiPo battery is being charged via AC or USB.

    The OUT pin will also be powered regardless if the battery is charging. 

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 40 points
    Anthony P Pham said:
    The output tracks the battery voltage when the device is only being powered by the battery (no USB power or AC power is present). If the output voltage falls below 200mV of the battery, a short is declared and the output voltage will be turned off. 

    So if I use a 3.7 V LiPo battery, do I also have an output voltage of 3.7 V?

    Anthony P Pham said:
    The OUT pin will also be powered regardless if the battery is charging. 

    Does the LDO pin then have the same function as the OUT pin? So can I use it to power the system with it?

  • 0 in reply to Svenja G.
    TI__Mastermind 23410 points

    Hi Svenja,

    Svenja G. said:
    So if I use a 3.7 V LiPo battery, do I also have an output voltage of 3.7 V?

    There will be a small dropout voltage that is dependent on load. At 1A, the dropout voltage is typically 40mV.

    Svenja G. said:
    Does the LDO pin then have the same function as the OUT pin? So can I use it to power the system with it?

    The LDO is powered by the input when the chip is enabled through the CE pin (CE = high is enabled). If the CE pin is low, the LDO is powered by the battery. The OUT pin will be powered regardless as a function of powerpath. You can use either to power your system assuming your system can handle 5V. If it is only 3.3V you will need to drop the voltage down. 

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 40 points

    Hi Anthony,

    Anthony P Pham said:
    There will be a small dropout voltage that is dependent on load. At 1A, the dropout voltage is typically 40mV.

    Is the 1 A the maximum continous charging current? But in the end I think the dropout voltage doesn´t really matter when I use a Step-down. 

    Do you think the Step-down TPS62290DRV is suitable to generate the 3.3 V voltage?

    Anthony P Pham said:
    You can use either to power your system assuming your system can handle 5V. If it is only 3.3V you will need to drop the voltage down. 

    I prefer to add 3.3V to my system. So it should be better that I feed the voltage of the OUT pin to a step-down converter.

    Is it possible to send you my schematics and check it for possible sources of error?

    Thanks for your help!

  • 0 in reply to Svenja G.
    TI__Mastermind 23410 points

    Hi Svenja,

    Svenja G. said:
    Is the 1 A the maximum continous charging current? But in the end I think the dropout voltage doesn´t really matter when I use a Step-down. 

    The 1A is the output current when the device is only being powered by the battery. The max charge current for the device is 1.5A when configured correctly. 

    Svenja G. said:
    Do you think the Step-down TPS62290DRV is suitable to generate the 3.3 V voltage?

    Taking a quick look, yes the TPS62290 looks like a good choice. 

    Svenja G. said:

    I prefer to add 3.3V to my system. So it should be better that I feed the voltage of the OUT pin to a step-down converter.

    Is it possible to send you my schematics and check it for possible sources of error?

    You can make a new thread for each device. I can take a look at the BQ24030-Q1 portion of the schematic. 

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 40 points
    Anthony P Pham said:
    Taking a quick look, yes the TPS62290 looks like a good choice.

    Thanks!

    Anthony P Pham said:
    I can take a look at the BQ24030-Q1 portion of the schematic.

    Do you have an email address to which I can send the schematic?

  • 0 in reply to Svenja G.
    TI__Mastermind 19195 points

    Hi Svenja,

    Is this for a school project? I think its okay for this to be uploaded here or shared in private chat.

    BR,

    Nick

  • 0 in reply to Nick Brylski
    Prodigy 40 points

    Hi Nick,

    yes, it is for my master thesis. I'll upload the schematic here. If you want, I can share it with you also in private chat. 

  • 0 in reply to Svenja G.
    TI__Mastermind 19195 points

    Hi Svenja,

    Some of the capacitor values are not labeled, can you provide the unmarked values?

    I recommend adding a 1uF cap on Bat.

    Anthony can take a look at this more when he gets back next week.

    Thanks

    Nick

  • 0 in reply to Nick Brylski
    Prodigy 40 points

    Hi Nick,

    Nick Brylski said:
    Some of the capacitor values are not labeled, can you provide the unmarked values?

    The values for the capacitors C3 and C4 are both 10 uF. 

    Nick Brylski said:
    I recommend adding a 1uF cap on Ba

    What is the 1 uF capacitor responsible for? 

    Nick Brylski said:
    Anthony can take a look at this more when he gets back next week.

    It would be fine. I am particularly unsure about the CE and PSEL pins.

    Thanks

    Svenja

  • 0 in reply to Svenja G.
    TI__Genius 10240 points

    Hi Svenja,

    We are closed on 07/05 in observance of the Independence Holiday and will get back to you when we return to the office by 07/07.

    Best regards,

    Eric

  • 0 in reply to Svenja G.
    TI__Mastermind 23410 points

    Hi Svenja,

    Svenja G. said:
    What is the 1 uF capacitor responsible for? 

    A 33uF capacitor (recommended but not required) in the BAT pin allows for operation when no battery is attached. It can also help for better voltage detection for the device. 

    Svenja G. said:
    I am particularly unsure about the CE and PSEL pins.

    The CE pin looks to be pulled high. This should be fine as this enables charge on this device. It also looks like you're using a switch for PSEL to switch between AC and USB. This should also be fine.

    As for the rest of the schematic, it looks like for USB charging, you have it set for 100mA (LOW on ISET) and about 1A  for AC charging. The TMR is configured for a safety timer of 3 hours. Everything else looks good!

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 40 points

    Hi Anthony,

    Anthony P Pham said:
    A 33uF capacitor (recommended but not required) in the BAT pin allows for operation when no battery is attached. It can also help for better voltage detection for the device. 

    Thanks!

    Anthony P Pham said:
    As for the rest of the schematic, it looks like for USB charging

    So does it make more sense to set the PSEL pin to low so that it fits better with the rest of the schematic? I would like to mainly charge via USB.Otherwise how do I have to change the schematics so that it is equally suitable for USB and AC?

    Anthony P Pham said:
    The TMR is configured for a safety timer of 3 hours.

    Is this safety time too long? Should I increase the resistance?

    Best Regards

    Svenja

  • 0 in reply to Svenja G.
    TI__Mastermind 23410 points

    Hi Svenja,

    Svenja G. said:
     I would like to mainly charge via USB.

    If you are mainly charging via USB, this is fine. It is ultimately your decision. It is already fairly suitable for both USB and AC, it's just you'll need to adjust the state of PSEL using your switch based on what is desired. I was only describing both operations to better understand the design as well as to ensure these are the settings you desired.

    Svenja G. said:
    Is this safety time too long? Should I increase the resistance?

    This will be something that is battery specific. If there is no safety timer listed in the battery specifications, you can estimate the expected charge time based on the capacity of your battery and the charge current. From there, you can adjust the safety timer to that value or slightly higher.

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 40 points

    Hi Anthony,

    Anthony P Pham said:
    If you are mainly charging via USB, this is fine. It is ultimately your decision. It is already fairly suitable for both USB and AC, it's just you'll need to adjust the state of PSEL using your switch based on what is desired. I was only describing both operations to better understand the design as well as to ensure these are the settings you desired.

    I think your explanation was very helpful. I was able to understand the design very well.

    Anthony P Pham said:
    If there is no safety timer listed in the battery specifications, you can estimate the expected charge time based on the capacity of your battery and the charge current.

    The capacity of my battery is 2000 mAh and the charge current of the standard-charging process is 400 mA (Constant current). This will be a expected charge time of about 6 1/2 hours. 

    If I use the maximum continuous charging current (1000 mA) for the calculation, this would be a charging time of 2 1/2 and the 30k-Resistor will be perfect. 

    So what charge current shout I use for the safety timer? If I use the charging current of 400 mA (for a safety timer of 6 1/2 hours), should I have to double the resistance or increase it to at least 60k?


    Best Regards,

    Svenja

  • 0 in reply to Svenja G.
    TI__Mastermind 23410 points

    Hi Svenja,

    You should set your safety timer based on those calculations with the charge current that you set. So if you expect the battery to be charged in 6.5 hours with a configured charge of 400mA, then the safety timer can be set for 6.5 hours. 7 hour setting would also be fine to give some headroom.

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 40 points

    Hi Anthony,

    But is it correct that I use the entry from the data sheet for the battery? Or do I have to use the 100mA of the ISET pin for the calculation?

    Best Regards,

    Svenja

  • 0 in reply to Svenja G.
    TI__Mastermind 23410 points

    Hi Svenja,

    I would recommend the entry from the datasheet for the battery if the datasheet contains a certain set of time.

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 40 points

    Hi Anthony,

    thank you very much for your help!

    I have a last question: The component BQ24030IRHLRQ1 is currently not available. I could use the IC BQ24030RHLR instead. Are there any other differences apart from the automotive sector? I have already compared the data sheets and found nothing serious here.

    Best Regards,

    Svenja

  • 0 in reply to Svenja G.
    TI__Mastermind 23410 points

    Hi Svenja,

    Yes, I do not believe there are any differences besides the automotive sector. If I do catch something that will affect operation, I will let you know.

    Best Regards,

    Anthony Pham