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TPS75003

Hello everybody!

I'm having troubles with the TPS75003.
I've to feed a Spartan 6 LX150, that requires 2A on the 2.5V output.

Obviously, the component should not be suitable since has a maximum output current of 0.3A.

I'm thinking to configure the 1.2V regulator normally, but to use the 3.3V buck regulator as a 2.5V regulator able to supply 5A rather than 3A simply changing the external components.

And this is the problem!
Looking to the DS of the component, it seems impossible to do it, and, since all the power components (MOS, inductance, diode, sense resistor) are external to the IC, I cannot understand why!

Is there anyone able to help me??

Thank you in advance for your answers

Paolo (Italy)

3 Replies

  • At the time when the IC was released, the IC's gate drive (SW pins) were not strong enough to turn on the available PFETs on the market fast enough in order to achieve currents higher than 3A.  Although we haven't tried it, It is possible that newer PFETs, like TI's CSD25211W1015 or equivalent have lower enough gate charge, that the TPS75003 gate drive can turn them on fast enough.  Alternatively, you can add a simple gate drive circuit, as shown here:  http://www.ti.com/litv/pdf/slva164, and use other FETs.

  • In reply to Jeff F:

    Hello Jeff!

    I want to thank you for your quick answer, but I have one more question for you...

    I read from the DS that the internal gate driver can supply up to 100mA.

    This means that, supposing to work at the maximum switching frequency of 300kHz (always from the DS) the maximum gate charge allowed should be in the range of 300nC.

    Is it right or not?

    In other words, which could be the maximum gate charge required from the external MOS to achieve higher currents leaving the IC the capability to work correctly?

    Thank you a lot for your answer!

    Paolo

  • In reply to Paolo Reggio:

    The 100mA spec in the datasheet is a DC load specification and is much lower than the peak current spike that the driver can deliver when driving the date of the PFET.  We do not characterize that peak value but it is well above 500mA.