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TPS65131-Q1 - PMP9780

Dice-K
Mastermind 6827 points
Other Parts Discussed in Thread: TPS65131-Q1, PMP9780, TPS65131

Hello,

I have five questions about PMP9780 of TPS65131-Q1.

 

Q1:About a calculation method of the power consumption .

Please teach me the calculation method of the power consumption  including the Charge Pump Circuit.

Is there the Excel?

 

Q2:About a Charge Pump Circuit.

Does the precision of the resistance need 1%? What is the reason?

Please tell me the meaning of the resistance of 2.2ohm connected to an INP-terminal.

 

Q3:About output capacitors.

4.7uF*4 is used by each output. Please teach me the setting of the ripple-value of this circuit.

 

Q4:About diodes of a Charge Pump Circuit.

Please teach me the reason of using BAT54S. Is Ifsm=600mA a requirement?

Please teach me the reason of using MBRM120. Is Ifsm=50A a requirement?

 

Q5:About Design-Tool (EXCEL).

If there is Design-Tool(EXCEL) to decide neighboring parts, please give me the EXCEL.

 

Regards,

Daisuke

  • 0
    TI__Guru 61245 points
    Hello Daisuke,

    Q1: We do not have a tool to calculate the power consumption of the circuit. You can roughly estimate the boost and buck-boost power consumption by checking out the efficiency curves given in the datasheet of TPS65131-Q1 for the 5.5V and -5V application. For +/- 6.3V, the efficiency will be slightly lower. We measured roughly 5% less compared to the datasheet curves.
    Charge pumps are very efficient, but the linear regulation at the output causes the biggest losses.
    So for the positive voltage tripler, you can estimate the power loss by (3*Vpos - VGH)*IGH.
    For the negative charge pump, you can estimate the power loss by (Vpos+|Vneg|-|VGL|)*IGL.

    Q2: The precision of the resistor divider as well has an influence on the precision of the output voltage. If you do not need the precision on VGL and VGH, you can use resistors with lower precision.
    The 2.2 ohm resistor in series to the flying caps limit the peak current drawn from the switch node. Using these resistors is good design practice.

    Q3: The amount of output capacitance is defined from the internal regulation of this IC, not by the ripple calculation of the output voltage.

    Q4: Both diode types are widely used in the industry.
    BAV99 is as well widely used in the industry but these are causing higher peak currents on the switch node. So we decided to use the BAT54S. The minimum current requirement for the diodes is twice the output current plus some margin for ripple current.
    For the boost converter a diode with a voltage rating of at least the output voltage with some margin is needed, for the buck-boost converter a diode with at least the voltage rating VIN+|Vneg| plus some margin is necessary.

    Q5: No, there is not such a design tool available. For TPS65131 I would recommend to use the components used either in this reference design or the ones used in the TPS65131 (non-Q1) EVM and just change the resistor dividers and the feedforward components as needed.

    Best regards,
    Brigitte