PC87373 datasheet(29/174 Pages) NSC

29 / 174 page

2.0 Power, Reset and Clocks (Continued)

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Revision 1.1

• The decoupling capacitor of the Standby 5V supply (V

SB5) pin

• The decoupling capacitor of the on-chip Core power converter (V

CORF) pin

• The decoupling capacitor of the Backup battery (V

BAT) pin

Note that a low-impedance ground layer also improves noise isolation.

Decoupling Capacitors. The following decoupling capacitors must be used in order to reduce EMI and ground bounce:

• Main power supply (V

DD3): Place one capacitor of 0.1 µF on each VDD3-VSS pin pair as close to the pin as possible. In

addition, place one 10

−47 µF tantalum capacitor on the common net as close to the chip as possible.

• Standby power supply (V

SB3): Place one capacitor of 0.1 µF on each VSB3-VSS pin pair as close to the pin as possible.

In addition, place one 10

−47 µF tantalum capacitor on the common net as close to the chip as possible.

• Standby 5V supply (V

SB5): Place one capacitor of 0.1 µF on the VSB5-VSS pin pair as close to the pin as possible.

• On-chip Core power converter (V

CORF): Place one 1 µF ceramic capacitor on the VCORF-VSS pin pair as close to the pin

as possible.

• Backup battery (V

BAT): Place one capacitor of 0.1 µF on the VBAT pin as close to the pin as possible.

Figure 2. Decoupling Capacitors Connection

2.2 RESET SOURCES AND TYPES

The PC87373 device has five reset sources:

• V

BAT Power-Up Reset - activated when VBAT is powered up.

• V

SB Power-Up Reset - activated when VSB3 is powered up.

• V

DD Power-Up Reset - activated when VDD3 is powered up.

• Hardware Reset - activated when the PCI_RESET input is asserted (low).

• Software Reset - triggered by SWRST bit in SIOCF1 register (see Section 3.7.2 on page 44); SWRST bit is set by the

host through the LPC interface.

VDD3

PC87373

0.1

µF

0.1

µF

0.1

µF

0.1

µF

VSS

VDD3

VSS

10-47

µF

Main 3.3V

VSB3

VSS

VSB3

VSS

0.1

µF

0.1

µF

0.1

µF

110

107

10-47

µF

Standby 3.3V

µF

VCORF

VSB5

0.1

µF

Standby 5V

Backup

0.1

µF

VBAT

Battery

PC87373 Datasheet(PDF) 29 Page - National Semiconductor (TI)

PC87373 Datasheet(HTML) 29 Page - National Semiconductor (TI)

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