PM6641 datasheet(41/47 Pages) STMICROELECTRONICS

Teilenummer	PM6641

Bauteilbeschribung	Monolithic VR for chipset and DDR2/3 supply for ultra-mobile PC (UMPC) applications

PDF	47 Pages

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Hersteller	STMICROELECTRONICS [STMicroelectronics]

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PM6641

Application examples

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Application examples

The following application examples are typical or customized applications. Each example

has been tested and evaluated and the schematic and BOM are available for reference

design.

9.1

UMPC DDR2 and chipset power supply

Figure 34. System architecture for DDR2 and chipset power supply

This application is conceived for real estate constrained portable equipment with DDR2

memory. An input power voltage pre-regulated to 3.3 V or 5 V is available and the available

output maximum power levels are shown in Figure 34. The switching regulator average load

is estimated to be about 50 % of the maximum load; this upper limit must be respected in

order to avoid dangerous stresses for internal power MOSFETs. The following table

resumes these current values.

Table 12. Expected average and peak currents for DDR2 and chipset power supply

Output rail

Max non continuous load [A]

Expected average load [A]

1.8 V (VDDQ)

2.5

1.3

0.9 V (VTT)

±2

0.3

1.5 V

2.8

1.4

1.05 V

PM6641

3.3V

VDDQ

1.8V @

VTT (LDO)

0.9V @ 2A

1.5V @

1.05V @ 4A

2.5A

2.8A

PM6641 Datenblatt(PDF) 41 Page - STMicroelectronics