Micros Systems Workstation 5 - Standby Domain Voltages; Vcc1.8 Sb; Vcc3 Sb; Vcc5 Sb

Workstation 5 Field Service Guide 2-35
Workstation 5 System Board Technical Descriptions
System Board Power Distribution
Standby Domain Voltages (REF: ABRD88 - Shts 8, 23 - 26 and 30)
Standby voltages are available when the unit is in the NOPOWER mode. A
100W open frame power supply produces +12V as long as the AC power cable
is connected to the unit.
Since the open frame power supply is active, removing the LCD/Touchscreen
assembly to check voltages exposes you to hazardous voltages on the power
supply heat sinks.
+12V
+12V enters the System Board at J16, Pins 1, 2, and 3 (Sht 23). Input
filtering is provided by inductors L8 and L9.
+12V is also fed through FB52 and F10 to Auxiliary +12V Power
Connector, J19. An future internal cable will connect between J19 and the
IO Panel to make +12V available.
VCC5SB
+5V Standby is produced by REG#1 in U38, a Triple Synchronous Buck
Controller. Control input SS_STBY1 is grounded through C264 to enable
this regulator as long as +12V is available.
Output load switching is handled by Q21A and Q21B through inductor L6
and cap EC29. The over current trip point is determined by R286/C290
across the TRIP1 input.
VCC3SB
VCC5SB is fed to adjustable voltage regulator U42, a AP1117_ADJ device
programmed to produce the VCC3SB (+3.3V) output. VCC3SB provides
standby power to the Ethernet Controller and Mini-PCI Socket.
VCORESB
On Sheet 25, Precision Micropower Shunt Voltage Reference D21 is
connected across VCC3SB to produce VCORESB. This standby voltage is
critical. It supplies power to the Power Management Controller (PMC) in
the Companion Device U41, allowing it to detect power button switch
closures.
VCC1.8SB
VCC5SB drives adjustable voltage regulator U28 to produce VCC1.8SB.
This is fed through FB37 to be labeled VCC_3_25_A. VCC1.8SB supplies
power to the analog power input of Ethernet Controller U22.