CD14538B: looking for a sample schematic

Hi Michael,

The first page of the datasheet gives this info:

You can only use one of the input triggers per channel - so either the +TR or the -TR should be terminated as explained above.

Other than that, this is the complete schematic:

I could draw it up with +TR tied to Vss and one with a connected to the signal source, but I don't think that would be much help for you.

Can you share your schematic?  What are you trying to accomplish?  What trouble are you having?

I'd probably go with a FET rated to a higher voltage - since BV_DSS(min) is exactly 12V, the FemtoFET might fail in your application. I'm certainly no expert on those devices though. If you want to be sure, you might make a new post with that part number to get the TI FemtoFET apps engineers to comment. Like most of our devices, the datasheet is probably a bit on the conservative side to protect TI.

As for driving the gate of the device with CD14538B, I would probably recommend a stronger driver. The outputs of this device are fairly weak - rated at 13.5V/6.8 mA of current for 15V typical operation. That makes for output drivers with about 220 ohm drive strength. With a 200pF gate capacitance on the FET, that will produce a relatively slow edge and with 2A of current could cause thermal damage to the device. You generally want a very fast turn-on when driving a power MOSFET.

If it were me, I'd use a 3.3V control logic with an SN74LVC1G123. That device has an output drive strength around 10 ohms (typical). It will give you an output edge rate about 20 times faster than the CD4k device.