SLIN-30E1AX Datasheet, PDF (17/26 Pages) Bel Fuse Inc. – 6.0 Vdc - 14 Vdc Input, 0.8 Vdc - 2.75 Vdc /30 A Outputs

NON-ISOLATED DC/DC CONVERTERS
6.0 Vdc - 14 Vdc Input, 0.8 Vdc - 2.75 Vdc /30 A Outputs
Jan. 11, 2010
Bel Power Inc., a subsidiary of Bel Fuse Inc.
Active Load Sharing
For additional power requirements, the SLIN-30E1Ax 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.
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 conditions 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 SLIN-30E1Ax
converters in parallel, the total current drawn should be less that 75% of (4 x 30A) , i.e. less than 90A.
• 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 over current 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.
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.
Tunable Loop^TM
The SLIN-30E1Ax modules have a new feature that optimizes transient response of the module called Tunable
Loop^TM.
External capacitors are usually added to the output of the module for two reasons: to reduce output ripple and
noise and to reduce output voltage deviations from the steady-state value in the presence of dynamic load
current changes. Adding external capacitance however affects the voltage control loop of the module, typically
causing the loop to slow down with sluggish response. Larger values of external capacitance could also cause
the module to become unstable.
The Tunable Loop^TM allows the user to externally adjust the voltage control loop to match the filter network
connected to the output of the module. The Tunable Loop^TM is implemented by connecting a series R-C between
the SENSE and TRIM pins of the module. This R-C allows the user to externally adjust the voltage loop feedback
compensation of the module.
Bel Fuse Inc. 206 Van Vorst Street, Jersey City, NJ 07302 • Tel [phone] • Fax [phone] • www.belfuse.com
17