Post by thread:Input impedence and transient current capability o

I would like to use one of my pic I/O pins to discharge a peak detector charing capacitor. I need to be able to discharge a 100pF cap from a maximium of +5v charge in about 15us. When I want to resume peak detection, I would simply put that pin in high impedence mode by setting its TRIS bit. My concern is whether the PIC pin can dischare my 100pF cap in 15us (enough transient current capability) and also whether it has a a high enough input impedence when I set the pic TRIS bit. I need leakage across the capacitor to be very low. I am using a poly cap by the way. I would appreciate any advice. Neil Gandler

On Mon, 18 Nov 1996, NEIL GANDLER wrote: > I would like to use one of my pic I/O pins to discharge a peak > detector charing capacitor. I need to be able to discharge a > 100pF cap from a maximium of +5v charge in about 15us. When I This shouldn't even be a hint of a problem, so I presume that you're writing "pF" where you mean some larger unit. 100nF (0.1 uF) probably would be dicey based on my first rough approximation.

On Mon, 18 Nov 1996, Martin J. Maney wrote: > On Mon, 18 Nov 1996, NEIL GANDLER wrote: > > > I would like to use one of my pic I/O pins to discharge a peak > > detector charing capacitor. I need to be able to discharge a > > 100pF cap from a maximium of +5v charge in about 15us. When I > > This shouldn't even be a hint of a problem, so I presume that you're > writing "pF" where you mean some larger unit. 100nF (0.1 uF) probably > would be dicey based on my first rough approximation. > No i definitely meant 100pf Neil