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An output Enable / Disable function is provided by using an optocoupler to control the Gate In pins
of the ConverterPAC™ assemblies. If the Enable / Disable control pin is pulled low, the optocoupler
turns on, pulling the Gate In pin low and disabling the ConverterPAC output. The nominal delay for an
output to come up when measured from release of the Enable / Disable pin is 10 – 15ms. The General
Shutdown function controls all outputs simultaneously and works in a similar manner.
The ride-through (hold-up) time is the amount of time the load can be supported before loss of output
regulation after the loss of input power. Detecting the loss of input power takes a finite time period
after which the AC Power OK signal goes from a TTL “1” to “0." This signal is available for use within
1.2s after initial power up and can be used to indicate an impending loss of power. At least 3ms of
warning time is given. Following the loss of input power, the outputs are disabled when the bus voltage
drops below its operating threshold.
Configuring and Reconfiguring MegaPACs
Most ConverterPACs of the same length can be inserted into any available slot of a MegaPAC chassis.
They can also be easily added, replaced or moved by sliding the assemblies in or out of a MegaPAC
chassis. For outputs greater than 200W, a driver QPAC™ and one or more booster ConverterPACs will
be used. For outputs greater than 600W, a driver FinQPAC™ and one or more booster ConverterPACs
will be used. Arrays of drivers and boosters should be configured so all boosters are placed in the slots
to the immediate right of the driver when looking at the output end of the MegaPAC.
Prior to removing or installing ConverterPACs, you must remove power from the MegaPAC
and wait five minutes. Failure to do so can result in personal injury or damage to the supply.
Take standard ESD precautions when handling ConverterPACs.
Removing ConverterPACs
ConverterPACs can be removed by loosening the captive screw at the base. Once this screw has been
loosened, the ConverterPAC will slide out of the chassis.
Once a ConverterPAC has been removed,
the empty slot MUST be filled with either another ConverterPAC or an airblock.
If the slot is left
empty, it will provide an airflow escape and cause failure to the power supply.
Line Filter
Rectifier
Soft Start
Circuit
Boost Converter
PFC Control
E/D Control
QPAC #1
QPAC #2
QPAC #3
QPAC #8
Fan
Housekeeping
Power
Current
Monitor
Customer
Interface
Power
Output
Power
Output
Power
Output
Power
Output
Input
High Voltage
DC Bus
Enable/Disable Control
Current
Sample
Waveform
Sample
Figure 1
PFC MegaPAC-EL™ and
PFC MegaPAC-HPEL™
low-noise architecture
