Categories

App note: Using High-Side NMOS drivers

Posted on Sunday, June 24th, 2012 in app notes by DP

Here is an app note describing how and why to use NMOS transistors for high-side switching operations, and how to implement it using associated drivers.

At first glance, P-channel MOSFETs appear to be the natural choice for high side switching. Unfortunately, the RDS(ON) exhibited by most P-channels is prohibitively high.(Mother Nature has decreed that electron mobility shall exceed hole mobility in silicon by about 2.5 times, so that a P-channel MOSFET with the same RDS(ON) and voltage rating as its N-channel counterpart is roughly 2 to 3 times larger and more expensive.) Also, the gate drive for a P-channel switch is limited to the supply voltage which may not fully enhance the switch as the supply voltage drops.

This entry was posted on Sunday, June 24th, 2012 at 9:00 pm and is filed under app notes. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.

4 Responses to “App note: Using High-Side NMOS drivers”

  1. Elias says:

    The link is wrong, it is from the article “http://dangerousprototypes.com/2012/06/24/app-note-msp430-based-usb-li-ion-battery-charger-and-fuel-gauge/” and points to the TI page.

  2. robert says:

    There is quite a lot of other useful information in this appnote. It was a good read.

  3. Filip says:

    sorry about that, it’s fixed now, thanks…

Leave a Reply

Notify me of followup comments via e-mail. You can also subscribe without commenting.

Recent Comments

  • Drone: So these go for around $330 USD and NO published calibration procedure online or otherwise? Given what's inside - I don't think I'll be considering...
  • Pekka Akselin: This is ridiculous!? :-) We are back at 256(!) byte EPROMs that needed multiple, a handful, of voltages to run! :-(
  • KH: Let's try a back-of-envelope calc balancing energies. From MCP1700 datasheet, there are graphs for a 200mA load step. Estimate the energy shortfall as 12uJ. Say...
  • Daniel: It's been a week and my comment is still awaiting moderation. Apparently the CIA doesn't want their involvement known?
  • KH: Agree, so okay, I guess he must have learned from somewhere. 100nF and 1000uF is so far apart, that was jarring; it's more magic incantation...