AN4192 datasheet(18/47 Pages) STMICROELECTRONICS

Part #	AN4192

Description	In the latest generation of CPUs for modern desktop and notebook platforms

PDF	47 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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18 / 47 page

High-side MOSFET selection

AN4192

18/47

Doc ID 023820 Rev 1

Figure 18.

Phase node waveform - standard configuration

Figure 19.

Phase node waveform - HS asymmetric gate drive configuration

Looking at the previous waveforms, due to the reduced HS turn-on speed, there is a clear

reduction of the phase node spike (21 V vs. 24.4 V), when the HS asymmetric gate drive is

used. Moreover, the LS gate-source bouncing, induced at HS turn-on, is smoothed.

Comparing the efficiency curves (Figure 20), the asymmetric gate drive has slightly better

efficiency (+0.7% at full load). This can be explained considering that:

The HS turn-off resistor is smaller (1.8

Ω vs. 2.2 Ω) and consequently the switching

losses at turn-off are lower.

Even if the HS turn-on resistor is bigger, the switching losses at turn-on are negligible.

AM16462V1

AM16463V1

AN4192 Datasheet(PDF) 18 Page - STMicroelectronics