2 added 513 characters in body edited Jan 21 '14 at 17:15 Spehro Pefhany 219k55 gold badges175175 silver badges454454 bronze badges In theory you could do what you are asking with a depletion-mode p-channel MOSFET, but they are not very common at all. It's easy to do this with two P-channel enhancement mode MOSFETs and a resistor if your switching speed requirement is not high. I'll edit this later to add a schematic when Circuitlab starts working again, but the idea is to have a small-signal p-channel MOSFET such as a BSS84, source to +3, gate to your input, drain to -10 through a suitable resistor (maybe 10K). simulate this circuit – Schematic created using CircuitLab Your power switch is also a P-channel MOSFET, and the source goes to groundTo use this simple circuit, the drain to the load and the gate to the drain of the BSS84. The power MOSFET has toQ2 must have a gate rated to be reliable with 10V drive. The small signal level shifting MOSFET Q1 must be a type that will be sufficiently turned on with -3V $$\V_{gs}\$$ It will switch "on" in a fairly sluggish manner if it's a big MOSFET, but that could be solved easily with additional drive circuitry (as can the $$\V_{gs(max)}\$$ > |+/- 10V| requirement). One attractive idea (if it fits your load requirements) might be to use a dual p-channel MOSFET, so you only require a resistor or two (one in series with the input might be advisable, depending on what is driving it) and a single ~2mm square package. In theory you could do what you are asking with a depletion-mode p-channel MOSFET, but they are not very common at all. It's easy to do this with two P-channel enhancement mode MOSFETs and a resistor if your switching speed requirement is not high. I'll edit this later to add a schematic when Circuitlab starts working again, but the idea is to have a small-signal p-channel MOSFET such as a BSS84, source to +3, gate to your input, drain to -10 through a suitable resistor (maybe 10K). Your power switch is also a P-channel MOSFET, and the source goes to ground, the drain to the load and the gate to the drain of the BSS84. The power MOSFET has to have a gate rated to be reliable with 10V drive. It will switch "on" in a fairly sluggish manner if it's a big MOSFET, but that could be solved easily with additional drive circuitry. In theory you could do what you are asking with a depletion-mode p-channel MOSFET, but they are not very common at all. It's easy to do this with two P-channel enhancement mode MOSFETs and a resistor if your switching speed requirement is not high. simulate this circuit – Schematic created using CircuitLab To use this simple circuit, the power MOSFET Q2 must have a gate rated to be reliable with 10V drive. The small signal level shifting MOSFET Q1 must be a type that will be sufficiently turned on with -3V $$\V_{gs}\$$ It will switch "on" in a fairly sluggish manner if it's a big MOSFET, but that could be solved easily with additional drive circuitry (as can the $$\V_{gs(max)}\$$ > |+/- 10V| requirement). One attractive idea (if it fits your load requirements) might be to use a dual p-channel MOSFET, so you only require a resistor or two (one in series with the input might be advisable, depending on what is driving it) and a single ~2mm square package. 1 answered Jan 21 '14 at 13:55 Spehro Pefhany 219k55 gold badges175175 silver badges454454 bronze badges In theory you could do what you are asking with a depletion-mode p-channel MOSFET, but they are not very common at all. It's easy to do this with two P-channel enhancement mode MOSFETs and a resistor if your switching speed requirement is not high. I'll edit this later to add a schematic when Circuitlab starts working again, but the idea is to have a small-signal p-channel MOSFET such as a BSS84, source to +3, gate to your input, drain to -10 through a suitable resistor (maybe 10K). Your power switch is also a P-channel MOSFET, and the source goes to ground, the drain to the load and the gate to the drain of the BSS84. The power MOSFET has to have a gate rated to be reliable with 10V drive. It will switch "on" in a fairly sluggish manner if it's a big MOSFET, but that could be solved easily with additional drive circuitry.