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TPS92660: Confirm the usage of ladj

zhang ping
Genius 3835 points
Part Number: TPS92660

As for the use of ladj, the PWM signal needs to be filtered by RC and shaped into a triangular wave input as shown in the figure below, right? Instead of directly inputting PWM signal.

  • 0
    TI__Expert 3920 points

    Hi Ping,

    No, the picture shows what happened when an analog input voltage placed on SADJ / LADJ pins.

    Once an analog voltage between 0.1 V and 2.5 V is there, it will be compared against an internal 500 Hz triangular voltage.

    Then the signal will become a 500 Hz PWM signal with corresponding duty cycle, e.g. 1 V turns into a 500 Hz 40% duty cycle PWM signal internally and PWM dim the corresponding LED string.

  • 0 in reply to Issac Hsu
    Genius 3835 points

    Whether I can input DC signal or PWM signal to control LED current at ladj pin ? It is indicated on datasheet as analog or PWM signal.

  • 0 in reply to zhang ping
    TI__Expert 3920 points

    Hi Ping,

    You can do either DC signal or PWM signal.

    If you do DC signal, please make sure the voltage level is between 0.1 V to 2.5 V.

    If you do PWM signal, please make sure the "0" voltage is < 0.1 V and "1" voltage is > 2.7 V.