AN4191 datasheet(16/20 Pages) STMICROELECTRONICS

No de pièce	AN4191

Description	This report shows the analysis performed on Power MOSFET devices

PDF	20 Pages

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Fabricant	STMICROELECTRONICS [STMicroelectronics]

Site Internet	http://www.st.com

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16 / 20 page

Rg impact for MOSFETs in buck/buck-boost configurations

AN4191

16/20

Doc ID 023815 Rev 1

Figure 22.

Synchronous buck converter schematic

In this board two different sample categories of the same device (20 V / 5A SLL Vth) are

compared: the “good” parts, with standard Rg (aligned to datasheet values) and the “bad”

parts, with high Rg values. The dynamic parameters are reported in Table 2 and 3.

The main analysis key points are:

●

Switching behavior evaluation and waveform capture

●

Driver/MOSFET thermal measurements at board startup.

In Figure 23 and Figure 24, the VDS and VOUT waveforms for “good” and “bad” parts,

respectively, are illustrated.

Table 2.

Dynamic parameters for “good” part

Ciss [pF]

Coss [pF]

Crss [pF]

Rg [Ω]

375.14

173.54

46.08

2.98

Table 3.

Dynamic parameters for “bad” part

Ciss [pF]

Coss [pF]

Crss [pF]

Rg [Ω]

335.14

172.48

41.99

125.02

AN4191 Fiches technique(PDF) 16 Page - STMicroelectronics