Subject to Export Control, see Cover Page for details. 1-3
1-3-2 DETAILED DESCRIPTION
The System Block Diagram (Figure 1-1) and the System Interconnect Diagram (Figure E-1) shows the
relationship of all assemblies. The following paragraphs are detailed descriptions of the 3500 /
3500A assemblies.
A. Power Supply PCB Assy (62A1A1) (Figure 1-2)
The Power Supply PCB Assy is responsible for supplying power to the internal modules for operation
and for charging the internal batteries. The Power Supply PCB Assy operates from externally
supplied DC power and provides simultaneous run and battery charge, or battery charge only. The
battery charge time increases when in the run and charge mode. The Power Supply PCB Assy
consists of a DC-DC Converter, ON/OFF Control circuitry and the Battery Charger circuitry. The
external DC input is supplied from an External DC Power Supply (supplied).
The internal batteries are removable/replaceable Li Ion battery packs with an internal "gas-gauge"
feature that allows accurate determination of remaining battery life. Maximum operating and storage
temperature for Li Ion batteries is -20° C to +60° C and the maximum charging temperature is 0° C to
+45° C.
The Power Supply PCB Assy contains a synchronous buck converter to convert the input voltage to a
fixed output voltage (+10 Vdc). The Power Supply PCB Assy also contains a low-pass filter to reduce
the amount of internal emissions. The Input Converter Assembly is capable of providing enough
output current to charge the battery at full current and run the Test Set at the same time, as long as
the input voltage is within range.
Battery Charger
The battery charger is a boost type converter. The battery charger monitors the battery voltage and
temperature to determine if the battery is capable of being recharged, and if safe to attempt to
recharge the battery. The battery must be at least at a 9.2 V level and the temperature must be
between 0° and 45° C before a charge cycle initiates.
Output Circuitry
The output converters are comprised of a dual-phase synchronous buck converter for developing
+3.3 and +5 V outputs. The converter also has an auxiliary output that is used to generate +18 V
from the +VS source (either the battery or input converter). A separate buck/boost converter is used
to generate the -5 V output. A separate buck converter is used to generate the +5.5 V output. The
primary converter provides dual phase control, as well as gate drive for the switching MOSFETS and
over-current protection. The main converter runs at 220 kHz, while the auxiliary converter runs at
1.2 MHz.
Both +3.3 and +5 V outputs are capable of delivering up to 3 A of current and the 16 V output can
deliver up to 80 mA. If any of these three outputs experience a severe over-current, the supply turns
OFF.
The -5 V converter is a stand-alone buck/boost converter that runs at approximately 220 kHz and can
deliver up to 400 mA of current before starting to fold back. If the supply experiences a severe over-
current condition, the supply stays in fold-back mode until the short is removed.
The +5.5 V converter is a stand-alone buck converter that runs at approximately 500 kHz and can
deliver up to 500 mA of current before starting to fold back. If the supply experiences a severe over-
current condition, the supply stays in fold-back mode until the short is removed.
To Next Page
Loading...
