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Original question:

TPS61085: About output current

TPS61085: whether TPS61085's EN has the hysteresis voltage

Amelie Zheng
Genius 10865 points
Part Number: TPS61085
Other Parts Discussed in Thread: LMR14020

Hi Team,

May I ask whether TPS61085 has the hysteresis voltage?

My customer wants to consider using TPS61085. However, the Vin of TPS61085 comes from Battery. The battery voltage may not be very stable and sometimes may have pulse. When EN connect with Vin, because of the pulse or noise from  Vin, the voltage of EN may be Low/High/Low/ High...

However if use the LMR14020's EN, which has Enable and Adjustable Under-voltage Lockout, this can be avoided. And Enable won't be influenced by pulse and noise...

As for TPS61085, do we have such function to avoid pulse and noise impact?

Thanks!

  • 0
    TI__Mastermind 34201 points

    Hi Amelie,

    Thanks for reaching out to us.

    TPS61085 EN pin high level input voltage minimum spec is 2V and low level input voltage maximum spec is 0.5V. Unless battery voltage drops below 0.5V, the device won't be disabled by EN pin. However, the input votlage UVLO rising & falling threshold is quite close to each other. So when battery voltage discharges close to 2.3V, the device on/off/on/off phenomenon may happen.

    As TPS61085 is a boost converter and inductor is at input, so the input current is continuous, adding input cap to filter the inductor current ripple will help decrease the input voltage ripple.

    Has customer already selected TPS61085 and draw schematic? You can share it here for review and tell me the working conditions: Vin range, Vout, IOUT.

  • 0 in reply to Zack Liu
    TI__Genius 10865 points

    OK. Thanks for reply. Customer now are choosing device and haven't made decision.

    So most of TI's boost doesn't have the function that have enable and adjustable under-voltage lockout,right?

  • 0 in reply to Amelie Zheng
    TI__Mastermind 34201 points

    Hi Amelie,

    Correct. Some devices EN logic high & low threshold is very similar to TPS61085. The Vin pin UVLO usually has some hysteresis voltage, like 100-200mV.

    What's the desired Vin range, Vout, Iout?