Data Sheet
Austin MegaLynxTM SMT: Non-Isolated DC-DC Power Modules:
2.7 – 4.0Vdc input; 0.8 to 2.0Vdc Output; 30A output current
October 21, 2009
at the SEQ pin is applied. This will result in sinking
current in the module if pre-bias voltage is present
at the output of the module. When pre-bias
immunity during start-up is required, the EZ-
SEQUENCETM feature must be disabled. For
additional guidelines on using EZ-SEQUENCETM
feature of Austin MegaLynx modules, contact the
Tyco Power Systems Technical representative for
the application note on output voltage sequencing.
•
All modules should be turned on and off
together. This is so that all modules come up at
the same time avoiding the problem of one
converter sourcing current into the other
leading to an overcurrent trip condition. To
ensure that all modules come up
simultaneously, the on/off pins of all paralleled
converters should be tied together and the
converters enabled and disabled using the
on/off pin.
Active Load Sharing (-P Option)
•
The share bus is not designed for redundant
operation and the system will be non-functional
upon failure of one of the unit when multiple
units are in parallel. In particular, if one of the
converters shuts down during operation, the
other converters may also shut down due to
their outputs hitting current limit. In such a
situation, unless a coordinated restart is
ensured, the system may never properly restart
since different converters will try to restart at
different times causing an overload condition
and subsequent shutdown. This situation can
be avoided by having an external output
voltage monitor circuit that detects a shutdown
condition and forces all converters to shut
down and restart together.
For additional power requirements, the ATM030
series power module is also available with a parallel
option. Up to five modules can be configured, in
parallel, with active load sharing. Good layout
techniques should be observed when using multiple
units in parallel. To implement forced load sharing,
the following connections should be made:
•
The share pins of all units in parallel must be
connected together. The path of these
connections should be as direct as possible.
•
All remote-sense pins should be connected to
the power bus at the same point, i.e., connect
all the SENSE(+) pins to the (+) side of the bus.
Close proximity and directness are necessary
for good noise immunity
When not using the parallel feature, leave the share
pin open.
Some special considerations apply for design of
converters in parallel operation:
When sizing the number of modules required for
parallel operation, take note of the fact that current
sharing has some tolerance. In addition, under
transient condtions such as a dynamic load change
and during startup, all converter output currents will
not be equal. To allow for such variation and avoid
the likelihood of a converter shutting off due to a
current overload, the total capacity of the paralleled
system should be no more than 75% of the sum of
the individual converters. As an example, for a
system of four ATM030A0X3-SR converters the
parallel, the total current drawn should be less that
75% of 4 x 30A or 90A.
•
When sizing the number of modules required
for parallel operation, take note of the fact that
current sharing has some tolerance. In
addition, under transient condtions such as a
dynamic load change and during startup, all
converter output currents will not be equal. To
allow for such variation and avoid the likelihood
of a converter shutting off due to a current
overload, the total capacity of the paralleled
system should be no more than 75% of the
sum of the individual converters. As an
example, for a system of four ATM030A0X3-
SR converters the parallel, the total current
drawn should be less that 75% of (4 x 30A) ,
i.e. less than 90A.
LINEAGE POWER
13
LINEAGEPOWER [ LINEAGE POWER CORPORATION ]
