power-deprived analog clamp - anything?

Sep 21, 2007 0 Replies

I have a small 3V-battery-operated device which has a switching power converter. The power converter gets turned off when not needed; when on, it generates two power supplies of ~ +/- 15V. Unfortunately, the analog output (much closer to a current source than a voltage source) running off the converted voltages emits transients on power-supply turn-on and turn-off. I need to clamp these transients to ground during this transition, without degrading the current-mode output during normal operation, and without taking up much board space, which is nearly as limited as the battery power.



Simply turning off a series switch between source and load tends to upset the current source driver, making the eventual turn-on even more problematic.



I haven't found any traditional analog switches that have the kind of power supply range (3V vs. 30+v). MOSFETs have those obnoxious parasitic diodes, and it would be ugly to control a pair of them (though it would work, albeit with series diodes that would prevent clamping tighter than a diode drop either side of ground).



Is there something obvious that I'm missing? Some magical part that I have forgotten or simply didn't know about? Something small, simple, available, and low power? Sure, I can dream can't I?



Thanks for any clues, hints, or commiseration!



-f


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