Power Control And Management - Agilent Technologies FieldFox N9923AN Service Manual

RF Vector Network Analyzer
N9923AN

Power Control and Management

Power States
The On/Off Button is used to switch between On, Off, and Standby power states:
Off Only the System Monitor and battery control circuits are powered up (if power is
available from the battery or external power).
If the battery is charging, the LED below the On/Off Button slowly flashes orange with
increasing intensity, otherwise this LED is off.
Some battery power is required in the "Off" state. A fully charged battery will discharge
completely in four to six weeks when left in the analyzer.
On This is normal operation. The On/Off Button LED is steadily lit green.
Standby Only the digital power supplies are on. The CPU is in a low power state,
maintaining RAM content. The On/Off Button LED flashes yellow briefly every two
seconds.
During normal operation, unexpectedly disconnecting power to the analyzer (such as
removing the main battery when the analyzer is not connected to external power) should
not cause any problems. Simply re-apply power. No firmware problems are expected. Of
course, this does not apply during a firmware upgrade.
Smart Power Management
The analyzer uses extensive "load switching" to minimize power dissipation. This is
termed Smart Power Management (SPM). There are two motivations for power
management:
• to extend battery run time
• to prevent overheating.
Sections of the circuitry are selectively powered down via "load switching", depending on
the operating mode of the analyzer. Five different sections of the circuitry on the A4 RF
board may be controlled via "load switching". These sections are as follows:
• Sources—switched to low power state between sweeps during CAT or NA modes.
• LO—switched to low power state when data is not being taken by receivers.
On the A5 system board, each of the ADC's may be individually switched to a low power
mode when not active.
Load switching is generally transparent to the user. One obvious exception is the that the
source turns off during "retrace" in the CAT and NA modes.
Service Guide N9923-90005
Theory of Operation
Grounding and Power
5-15