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LP5907: Vout capacitance

Lillian Liu(SH)
Expert 3080 points
Part Number: LP5907
Other Parts Discussed in Thread: TPS7A20

Hi team,

May I ask if the output capacitance of Lp5907 exceeds 10uF; what will be the problem? The load capacitance in the current circuit is 47uF;

Thanks

Lillian

  • 0
    TI__Mastermind 29410 points

    Hi Lillian,

    The LP5907 has a risk of becoming unstable and oscillating with higher values of load capacitance.  I strongly recommend looking at the TPS7A20.  The TPS7A20 is the next generation device from the LP59xx family.  The TPS7A20 offers higher current, a revamped compensation which is stable for loads up to at least 200uF, and is cheaper.  The only reason to still use the LP5907 in new designs is if you absolutely must have the fastest startup possible. For most designs, you will select the TPS7A20 over the LP59xx.

    Thanks,

    Stephen

  • 0 in reply to Stephen Ziel
    TI__Expert 3080 points

    Hi Stephen,

    Thanks for your reply

    startup time need <150us;

    Need shows as below.

     

    part number

    vin

    2.2 V to 5.5 V

    PSRR(100 kHz)

    68db

    Low output voltage noise

    6.33

    Output voltage tolerance

    ±2%

    Very low IQ (enabled)

    20uA

    dropout

    <175mv

    Current

     >250mA

    Start up

    135us

    PACKAGE

    SOT-23 (DBV) | 5

    COUT

     

    ESR

    <2ohm

    Do you have any other suitable recommend?

    Thanks 

    Lillian

  • 0 in reply to Lillian Liu(SH)
    TI__Mastermind 29410 points

    Hi Lillian,

    Based on these requirements, the LP5907 is the best choice.  Is this an large opportunity? I would suggest that we look at submitting a transistor simulation to confirm stability with this load.  I'll need the following data if you wish to go this route:

    1. Vin, Vout
    2. Ambient temperature
    3. Cin (each capacitor please, not a lumped capacitance)
    4. Cout (each capacitor please, not a lumped capacitance)
    5. Minimum and maximum load current

    Thanks,

    Stephen