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REF2033: Turn on time

Guru 54027 points
Part Number: REF2033

Datasheet lists 500us Ton yet signal Fig.29 settling 1% <1us @100us/Cm scope grid.

What is the turn on delay time In to Out? 

How on earth did it require 500us to power the output to 1% settling (3v3)?

Seemingly the datasheet misprints turn on time 500us, should have been 25us @1% settling? 

  • Hi,

    The 500us is a typical number and can vary from device to device.
    Figure 29 does have a ramp in the first 50us to a value close to Vout but it is not within 1%.
    After the initial 50us the device rises slowly to a value of 1% of its Vout. This is more difficult to see on this graph since the resolution is low.

    -Marcoo
  • Hi Marcoo Z

    Marcoo Z said:
    The 500us is a typical number and can vary from device to device

    If indeed 500us is correct how can it take that long to power up when TPS73533 is only 45us with 1nf CNR load.

    Marcoo Z said:
    After the initial 50us the device rises slowly to a value of 1% of its Vout

    Ok I see the 2v/Cm but still question why takes so long to power up @500us, somehow part of slower transient response? Oddly PSRR easily passed 12.5khz PWM (80us) periods thus made it seem a fast reacting device to transients. Yet the 1uf load Fig.22 shows very slow transient response 500us pulse, where >80us periods quickly passed through to Vref pin 5.

    Thanks for explaining the 500us in detail :-)