AN4192 datasheet(28/47 Pages) STMICROELECTRONICS

Part #	AN4192

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

PDF	47 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

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28 / 47 page

Low-side FET selection

AN4192

28/47

Doc ID 023820 Rev 1

Figure 31.

LS with monolithic Schottky diode waveforms @ 20 A

The efficiency improvement caused by an optimized LS body diode can be appreciated only

if the converter switching frequency increases: in fact, the higher the fSW, the larger the

reverse recovery losses (see (5)). We compare the above mentioned LS FETs (LS and

LS+Sch.) in a 2-phase synchronous buck converter (VIN = 12 V, VOUT = 1.5 V, fSW = 610

kHz, 2 x HS, 2 x LS, IOUT = 60 A - Figure 32). External gate resistances are connected to

HS (2.2

Ω) and LS (2.2 Ω) FETs. No snubber network is mounted on the board.

As can be seen in Figure 33, at high output currents, due to lower diode conduction and

reverse recovery losses, the solution with LS+Sch. has higher efficiency (+1.5% at full load).

AM16474V1

AN4192 Datasheet(PDF) 28 Page - STMicroelectronics