PM6670AS datasheet(46/54 Pages) STMICROELECTRONICS

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Application information

PM6670AS

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Tested low-side MOSFETs are listed in Table 10.

Dual N-MOS can be used in applications with lower output current.

Table 11

shows some suitable dual MOSFETs for applications requiring about 3 A.

8.1.5

Diode selection

A rectifier across the synchronous switch is recommended. The rectifier works as a voltage

clamp across the synchronous rectifier and reduces the negative inductor swing during the

dead time between turning the high-side MOSFET off and the synchronous rectifier on.

Moreover it increases the efficiency of the system.

Choose a schottky diode as long as its forward voltage drop is very little (0.3 V). The reverse

voltage should be greater than the maximum input voltage VINmax and a minimum recovery

reverse charge is preferable. Table 12 shows some evaluated diodes.

Table 10. Evaluated low-side MOSFETs

Manufacturer

Type

RDSon (mΩ)

CGD \ CGS

Rated reverse voltage (V)

STS12NH3LL

13.5

0.069

STS25NH3LL

4.0

0.011

IRF7811

0.054

Table 11. Suitable dual MOSFETs

Manufacturer

Type

RDSon (mΩ)

Gate charge (nC)

Rated reverse voltage (V)

STS8DNH3LL

IRF7313

Table 12. Evaluated recirculation rectifiers

Manufacturer

Type

Forward

voltage (V)

Rated reverse

voltage (V)

Reverse current (

µA)

STPS1L30M

0.34

0.00039

STPS1L30A

0.34

0.00039

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