Keysight FieldFox Handheld Analyzers Service Guide 73
Theory of Operation
Grounding and Power
Voltages and Power Supplies
The following power supplies exist within the analyzer:
— Digital 5 volts
Generated from Unreg DC on the A3 Front Panel Interface board, controlled
by the System Monitor on the A5 System board, and used on the A3, A4,
and A5 boards.
— Digital 3.3 volts
Generated from Unreg DC on the A3 Front Panel Interface board, on/off
functions controlled by the System Monitor on the A5 System board, and
used on the A2 LCD assembly and A3, A4, A5, and A6 boards.
— Analog supply voltages
Seven separate voltages generated from Unreg DC on the A5 System
board, on/off functions controlled by the System Monitor on the A5 System
board.
— LCD backlight voltage
Generated on the A3 Front Panel Interface board from the digital 5 volt
supply voltage.
— Power for the System Monitor circuit
+3.3 volt circuit powered from Ext DC or Batt +, whichever is greater. Used
on A5 System board only.
— Unreg DC
From Ext DC or Batt +, 21 volts max.
— Ext DC
From external Power AC Adapter, nominal 15 volts, acceptable up to 19
volts.
— Batt +
From main battery, nominal 12 volts.
— +10 DC (N995xA, N996xA only)
Provides supply voltage to the nano switch on the RF board.
— -10 DC (N995xA, N996xA only)
Provides supply voltage to the nano switch on the RF board.
All voltages except Ext DC, Batt +, and the System Monitor power can be
turned on/off within the analyzer. Refer to “Power Management Circuitry” on
page 66 for more information.
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