Micros Systems Workstation 5 - Vcore; Working, Standby and System Reset

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Workstation 5 Field Service Guide 2-37

Workstation 5 System Board Technical Descriptions

System Board Power Distribution

VCORE

VCORE is the primary LX800 Processor supply voltage and is active in the

WORKING domain.

System Boards up to Revision E use the ALXC800EETJCVD variant of

the LX800 that requires a VCORE of 1.20V. R282 in the VCORE

Regulator Circuit is 511Ω.

System Boards Revision F or later use the ALXD800EEXJCVD C3 variant

of the LX800 that requires a VCORE of 1.25V. R282 in the VCORE

Regulator Circuit is 562Ω.

Working, Standby and System Reset

When power is applied to the Companion Device from a cold start (e.g., the

AC power cable is connected to the unit) the external sub-system must assert

RESET_STAND# as Standby power is applied, followed by RESET_WORK#

as Working power is applied.

RESET_STAND# (Reset the Standby Power Domain) is provided by U48, a

LP3470 Tiny Power On Reset Device located on Sheet 8. This device is

designed to monitor a specific power supply voltage (in this case VCC5SB)

and assert RESET_STB# when the input voltage falls below the

pre-programmed threshold of 3.08V. The reset remains asserted for an interval

determined by C496. When VCC5SB rises above a threshold of 3.08V,

RST_STB# remains asserted for a period programmed by C496, then

de-asserts.

RESET_WORK# (Reset the Working Power Domain) is generated by U47, a

second LP3470 Tiny Power On Device located on Sheet 26. U47 is also

programmed to activate at 3.08V, but the input is tied to VCC3SB. The reset

remains asserted for an interval determined by C489. When VCC3SB rises

above a threshold of 3.08V, RST_WORK# remains asserted for a period

programmed by C489, then de-asserts.

In response to the RESET_WORK# and RESET_STANDBY# inputs, the

Companion Device asserts RESET_OUT, referred to on the schematic as

PCI_RST#. PCI_RST# is the master system board reset, fed to all major

components including the LX800 processor, BIOS Chip, Ethernet Controller,

Super IO #1 and 2, Audio Codec, and Mini-PCI Connector CN11.

All three reset signals are required to start the system board processor.