SLIN-20E1A_10 Datasheet, PDF (19/26 Pages) Bel Fuse Inc. – NON-ISOLATED DC/DC CONVERTERS

NON-ISOLATED DC/DC CONVERTERS
4.5 Vdc - 14 Vdc Input, 0.69 Vdc - 5.5 Vdc /20 A Outputs
December 10, 2010
Bel Power, Inc. , a subsidiary of Bel Fuse, Inc.
Power Good
The SLIN-20E1Ax modules provide a Power Good (PGOOD) signal that is implemented with an open-drain
output to indicate that the output voltage is within the regulation limits of the power module. The PGOOD signal
will be de-asserted to a low state if any condition such as over temperature, over current or loss of regulation
occurs that would result in the output voltage going ±11% outside the set point value. The PGOOD terminal
should be connected through a pull-up resistor (suggested value 100KΩ) to a source of 6VDC or less.
Synchronization
The SLIN-20E1Ax modules can be synchronized using an external signal. Details of the SYNC signal are
provided in the Electrical Specifications table. If the synchronization function is not being used, leave the SYNC
pin floating.
Tunable Loop^TM
The SLIN-20E1Ax 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, as shown below. This R-C allows the user to externally adjust the
voltage loop feedback compensation of the module.
VOUT
SENSE
RTUNE
MODULE
CO
CTUNE
TRIM
GND
RTrim
Circuit diagram showing connection of R_TUNE and C_TUNE to tune the control loop of the module
Recommended values of R_TUNE and C_TUNE for different output capacitor combinations are given in Tables 2 and 3.
Table 2 shows the recommended values of R_TUNE and C_TUNE for different values of ceramic output capacitors up
to 940uF that might be needed for an application to meet output ripple and noise requirements. Selecting R_TUNE
and C_TUNE according to Table 2 will ensure stable operation of the module.
In applications with tight output voltage limits in the presence of dynamic current loading, additional output
capacitance will be required. Table 3 lists recommended values of R_TUNE and C_TUNE in order to meet 2% output
voltage deviation limits for some common output voltages in the presence of a 10A to 20A step change (50% of
full load), with an input voltage of 12V.
Bel Fuse Inc. 206 Van Vorst Street, Jersey City, NJ 07302 • Tel [phone] • Fax [phone] • www.belfuse.com
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