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TPS63031: TPS63031

ANURAJ NK
Intellectual 510 points
Part Number: TPS63031

Hi,

    Datasheet of TPS63031 has parameter related input voltage  as below.

1. Input voltage range

2. Minimum input voltage for start-up

   

Please let me know, what is the difference between Minimum input voltage range and minimum input voltage for start up ?

Can the device functionality is 100% at minimum startup voltage?  During minimum startup voltage what will be the status of output voltage and output current.

Regards

Anuraj NK

  • 0
    TI__Expert 5425 points
    The input voltage range is defining the supply voltage range for normal operation. The minimum input voltage range for start-up defines the lowest voltage which the device needs at the input for start-up. As you can see in the spec this can be as high as 2.0V.
    Figure22 and Figure 23 in the datasheet show typical start-up curves. You can see find output voltage and output current waveforms there.
  • 0 in reply to Juergen
    Intellectual 510 points
    In Fig 22 and 23 , Vin is 2.4V and 4.2V respectively. My query was, during minimum startup voltage of 1.6V what will be the status of output voltage and output current ?

    I am looking for procedure to validate this minimum startup voltage value. I force 1.6V to input and what will be the status of output at that time?
  • 0 in reply to ANURAJ NK
    TI__Expert 5425 points
    For reliable start up you need at least 2.0V at the input. When the output voltage has settled you can reduce the input voltage down to 1.8V.
  • 0 in reply to Juergen
    Intellectual 510 points
    I am confused with the answers. What is the significance of minimum startup voltage, because the designers will ensure that the minimum Vin (1.8V) is provide for its normal operation while designing the circuit.
  • 0 in reply to ANURAJ NK
    Intellectual 510 points

    I am confused with the answers. What is the significance of minimum startup voltage, because the designers will ensure that the minimum Vin (1.8V) is provide for its normal operation while designing the circuit.

    while testing this parameter,what should be the output load current.

  • 0 in reply to ANURAJ NK
    TI__Expert 8420 points
    To ensure start up of the device 2V is needed at the input (but 1.6V may be enough as shown in the datasheet). Once started the device can operate down to 1.8V.
    This is a typical scenario for battery powered applications, When the battery is full the input voltage is above 2V which ensure the start up of the device. When the battery discharges and is toward the end of its life, the cut-off voltage can go as low as 1.8V.
  • 0 in reply to Sabrina
    Intellectual 510 points
    Can I test this parameters as per below procedure.
    1. Force 2V to input and set output to 3.3V and load 100mA (Please confirm this current)
    2. Reduce the input voltage and make it 1.6V. Ensuring that at 1.6Vin also the output voltage and current should be stable.


    Please confirm this procedure.
  • 0 in reply to ANURAJ NK
    TI__Expert 8420 points
    Please note the change in step 2:
    2.Reduce it down to 1.8V (in the electrical characteristics Vin is specified down to 1.8V for stable operation )
  • 0 in reply to Sabrina
    Intellectual 510 points
    As per the datasheet, minimum voltage is 1.6V. We are expecting the IC to work when the startup voltage is 1.6 or above, am i right?
  • 0 in reply to ANURAJ NK
    TI__Expert 8420 points
    I think you are confusing Vin and start up voltage. The Vin is specified down to 1.8V in the electrical specification table.
  • 0 in reply to Sabrina
    Intellectual 510 points

    My query is regarding the minimum input voltage for startup. The highlighted value shows 1.6V not 1.8V. 

    I am expecting that, once input voltage reduces to 1.6V which is the minimum input voltage for startup, the IC should provide the set output voltage and deliver the load current of 100mA as mentioned in the procedure shared earlier. 

    Datasheet screen shot attaching for minimum input voltage for start up value.

  • 0 in reply to ANURAJ NK
    TI__Expert 8420 points

    At 1.6V some devices may start and some not. This is the reason there is a minimum, tyical and maximum value for the minimum start up voltage. This line of the datasheet tells that between 0deg and 85degC some device may already start at 1.6V  but ensures that at Vin=1.9V all the device will definitely start. It does NOT ensure stable operation at 1.6V

    Regarding  "Vin Input Voltage  range"

    it ensure stable operation of the device. So if you go below 1.8V we can not expect stable operation.

    All these  questions have already been answered in the previous posts which revolves arround "the difference between minimum startup voltage and Input voltage range. ", but still  I feel we are moving in a loop.

    To help you move forward with your project, I would stronlgy suggest to follow the procedure you suggested below, with taking care of reducing the Vin down to 1.8V in  the second step. As a conclusion You can not expect the device to operate stable at Vin=1.6V

    "Can I test this parameters as per below procedure.
    1. Force 2V to input and set output to 3.3V and load 100mA (Please confirm this current)
    2. Reduce the input voltage and make it 1.6V  1.8V. Ensuring that at 1.6Vin 1.8V also the output voltage and current should be stable."

  • 0 in reply to Sabrina
    Intellectual 510 points
    Thanks for your patience for typing long replay mail and detailed answer. This clarify my query.