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power-down with THS3095

Other Parts Discussed in Thread: THS3095

Hello,

I have problems with power down of THS3095. Regardless of level of voltage at pin 8 (nPD) - the device is always enabled (indicated by power consumption, voltage levels and amplifying function). At first: there is a single-supply situation.

The related voltage levels are: pin 4 = 0V (ground), pin 7 = +15V (positive rail), pin 1 = 0V (REF), pin 8 = 0V/+3.3V (nPD). Even if nPD and REF are at the same level (0V related to Ground) the device is activ - where it should be in power-down.

Any idea from someone?

regards

Karsten

  • Karsten,

    Are there any signals/voltages appearing on either the input or output when placed into PD mode? The reason for the question is that the THS3095 is a current feedback amplifier (CFB) and one of the drawbacks to the architecture of CFB's is that they can self-turn on. This is explained a bit more detail in the datasheet - pages 20-21 with the critical aspect of this discussion on page 21 - first paragraph.

    Cheers,

    Randy

  • Hi Randy,

    Thanks for your hint regarding page 21 of datasheet - it is the answer. After disabling my input signal to THS3095 it went to power-down....

    regards

    Karsten