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BQ76930: LDO 3.3V (TS1)

Alexander Burtakov
Intellectual 750 points
Part Number: BQ76930
Other Parts Discussed in Thread: TIDA-00792, , BQ78350

Hello to Ti support team ,

       I have question according use 3.3V LDO (TS1) source as direct supply to my leds (sum current ~12mA) . The limitation according data sheet minimim 30mA , but according to EVM and TIDA-00792 your implementation is through source follower .

B.R

Alexander Burtakov 

  • 0
    TI__Mastermind 42535 points
    your question will be answered during a weekday.
  • 0
    TI__Guru 54715 points
    Hi Alexander,
    The "EXTERNAL REGULATOR" section of the electrical characteristics in the bq76930 data sheet shows that the short circuit output current can be as low as 30 mA (zero volts out). Regulated voltage levels are shown with 10 mA and 20 mA loads
    In the TIDA-00792 the bq78350 is used which needs 10 mA for flash update, and 5 LEDs are supported each which could use 3 mA nominal for 15 mA. Like the EVM this 25 mA load was beyond the 20 mA load specification, so an alternate source was used for the LEDs.
    If you have a 3.3V REGOUT part you are not likely using the bq78350 (2.5V supply). If your LED load is 12 mA max you have another 8 mA of output current available for your MCU or other circuit while staying in the defined output region.
  • 0 in reply to WM5295
    Intellectual 750 points

    Thank  for your respond ,

                  What  Is the current load limit for  "internal LDO" CAP1 (pin 7) ?

    B.R 

  • 0 in reply to Alexander Burtakov
    TI__Guru 54715 points
    Hi Alexander,
    There is no specification for load current or regulation on the CAP1 pin. CAPn is an internal 3.3V regulator which was not intended for external use. The LED reference was determined suitable with a high gain transistor.