• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 62 subscribers
  • Views 144 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

BQ24450: Implementing Temperature Cutoff for Lead-Acid Charging with BQ24450

user4860691
Intellectual 330 points
Part Number: BQ24450


Tool/software:

I'm designing a circuit to charge a 12V lead-acid battery using the BQ24450DWTR IC.
Key charging parameters are:

  • Float voltage: ~13.8 V

  • Boost voltage: ~14.7 V

  • Maximum charge current: ~300 mA

  • Pre-charge current: ~10 mA

  • Charging should be disabled below 0°C or above ~50°C

Do I need to use an NTC thermistor to control the charging temperature range?

If so, how should I connect and configure the NTC for proper temperature-based charging cutoff?

If so, how should I connect and configure the NTC for proper temperature-based charging cutoff?

  • 0
    TI__Guru* 76756 points

    Hello

    user4860691 said:
    Do I need to use an NTC thermistor to control the charging temperature range?

    The BQ24450 does not support an external NTC for controlling charging temp.

    The internal Voltage Reference is temp compensated and will reduce charging voltage as temp increases.

  • 0 in reply to Bill Johns
    Intellectual 330 points

    How can I disable charging with the BQ24450 when the battery temperature is below 0°C or above ~50°C?

    Is there an internal configuration to handle this, or should I use an external temperature sensor?

    If external control is needed, can I simply use a microcontroller GPIO to pull Pin 12 (CE) high or low to enable or disable charging based on temperature readings?

  • 0 in reply to user4860691
    TI__Guru* 76756 points

    Hello

    user4860691 said:
    Is there an internal configuration to handle this, or should I use an external temperature sensor?

    Internal configuration is not an option, the external temp circuit is best option.

    user4860691 said:
    If external control is needed, can I simply use a microcontroller GPIO to pull Pin 12 (CE) high or low to enable or disable charging based on temperature readings?

    Yes this is an option pulling CE low will put unit in PRE-CHG mode, turn off Q900.