Did you scope it with the darlington in circuit? If so, the base of the darlington would clamp the drive voltage to about 1V. On Wed, Jun 10, 2015 at 8:19 PM, Neil wrote: > > On 6/5/2015 6:47 PM, James Cameron wrote: >> Yes, you'd need to use the switching design, otherwise by using >> a MOSFET you'd lose the peak and hold part of the Figure 1 design. > Right. > >> You'd best scope the drive voltage to be sure; it isn't specified. > > Just did ... looks like around 1V. So looks like I've have to drive > the mosfet with another transistor. > > >> Figure 23 shows a fairly conventional output stage on pin 2, but it's >> a simplified schematic. >> >> If you have assembly constraints, you might instead work to improve >> cooling. >> >> Google LM1949 MOSFET for other discussions. >> > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .