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TPS76850QPWPRPQ1 - DROPOUT VOLTAGE vs FREE-AIR TEMPERATURE and ESR

Hirotaka Matsumoto
Guru 27595 points

Hi all,

Would you mind if we ask TPS76850-Q1?

Our customer will use TPS76850-Q1 like as following conditions;

-Conditions-
Input: DC6V
Output: DC5V
Iout: Max 650mA

<Q1>
The datasheet P11 shows Figure14 "TPS76833 DROPOUT VOLTAGE vs FREE-AIR TEMPERATURE".
So, do you have "TPS76850 DROPOUT VOLTAGE vs FREE-AIR TEMPERATURE" with  Io=650mA?
Or, if you don't have it, should we explain to our customer to use Vdo=380mV for the design?

<Q2>
How much is the recommended value of following capacitances in above conditions?  
-Input capacitance Ci
-Output capacitance Co
And then. if you have some recommended Equivalent series resistance(ESR), could you let us know it?

Kind regards,

Hirotaka Matsumoto

  • 0
    Guru 27595 points

    Hi team,

    We guess that your team is so busy.
    However if you have some adivice, could you let us know it?

    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Hirotaka Matsumoto
    Guru 27595 points

    Hi team,

    We guess that following;

    <Input capacitance: Cin>
    The minimum recommended capacitance value is 0.1uF with ceramic condenser, isn't it?

    <Output capacitance: Cout>
    The minimum recommended capacitance value is 10uF and the ESR must be between 50mΩ and 1.5Ω.

    Is our recognition correct?

    Kind regards,

    Hirotaka Matsumoto

  • 0
    TI__Expert 5675 points
    Hi Hirotaka,

    Q1:
    I am sorry but this is an old device and we don't have the data you required.
    However, as you know, the dropout voltage rise as the current and temperature increasing.
    380mV is the value covers the full current and temperature range, and yes, customer could use it for design.

    Q2:
    You could find detailed information in datasheet page 15, 'external capacitor requirements' section.
    Ci:
    An input capacitor is not usually required; however, a ceramic bypass capacitor (0.047 µF or larger) improves load transient response and noise rejection if the TPS768xx is located more than a few inches from the power supply. A higher-capacitance electrolytic capacitor may be necessary if large (hundreds of milliamps) load transients with fast rise times are anticipated.
    Yes, minimum 0.1uF ceramic capacitance is OK!
    Co:
    Yes, the minimum recommended capacitance value is 10 µF and the ESR must be between 50 mΩ and 1.5 Ω. Capacitor values 10 µF or larger are
    acceptable, provided the ESR is less than 1.5 Ω.

    Best regards,
    Jason Liu