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TLVH431 and TPS65070

rdjcodo13
Prodigy 70 points
Other Parts Discussed in Thread: OMAP-L138, TLVH431

Hello everyone,

The problem is related to the TSP65070 to power the DSP OMAP, as specified in the OMAP Errata Sheet "Errata Sheet_OMAP-L138 C6000 DSP+ARM Processor" page 25, the voltage of the DVDD18 can pull up to 2,7V When using Dual-Voltage IOs at 3.3V. One of the solutions is to use the regulator TLVH431 as is shown in the following discussion:

The problem in this solution is the current provided by the TLVH431 is 70mA, but the maximum leakage current will be 140mA, so can anyone tell me what is the solution, if the use of two TLVH431 doesn't work. Is there any other regulator can provide 140mA ?

Thanks,

 Rachid

  • 0
    TI__Mastermind 24485 points

    Hello Rachid,

    You are correct that the TLVH431 can only provide 70mA of the required 140mA load.
    The errata states the the TLVH431 can provide up to 70mA of additional load current, acknowledging that the TLVH431 alone is not enough.

    The errata also states the following:
    So this error state can be prevented by ensuring that the load on the DVDD18 supply during the DVDD3318_x supply ramp exceeds 140mA. This can be achieved by any combination of the following as long as they cumulatively produce >140mA load on DVDD18 during the DVDD3318_x ramp period...

    The key point from the above statement is that it can be achieved by "any combination" of the following with the TLVH431 only being part of the solution.
    I was not able to find a shunt regulator that would work in this application that can provide up to 140mA.

    Others have been able to solve this problem by combination of the following:

    • capacitance + transistor-enabled resistors
    • capacitance + shunt regulator
    • diode + resistor to GND
    • capacitance + faster slew rate

    Best Regards,
    Michael

  • 0 in reply to Michael J Schultis
    Prodigy 70 points

    Hi Michael,

    Thanks for you answer, when you say others, do you mean than these solutions worked ? Do you have any example ?

    For the solution capacitance + faster slew rate: you mean by using high speed OP amp + bulk capacitors to limits the power supply impedance ?

    Best regards,

    Rachid

  • 0 in reply to rdjcodo13
    TI__Mastermind 24485 points

    Hello Rachid,

    Yes, we are aware that solutions like these worked in the past, unfortunately I am not aware of any specific examples.

    As for the cap + slew rate solution, again I am not aware of any specific examples, just that if the slew rate is increased then less overall energy is transferred to DVDD18 and therefore a lower load will be necessary.

    Just as it is described in Table 12 of the OMAP-L138 Errata: http://www.ti.com/lit/er/sprz301m/sprz301m.pdf 

    Best,
    Michael