App note: Using High-Side NMOS drivers

in app notes by DP | 4 comments

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.

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Comments

  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…

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