SLIN-03F2A Datasheet, PDF (18/26 Pages) Bel Fuse Inc. – NON-ISOLATED DC/DC CONVERTERS

NON-ISOLATED DC/DC CONVERTERS
2.4 Vdc - 5.5 Vdc Input, 0.6 Vdc - 3.63 Vdc /3 A Output
December 10, 2010
Bel Power Inc., a subsidiary of Bel Fuse Inc.
Tunable Loop^TM
The SLIN-03F2Ax 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.
VOUT
SENSE
MODULE
TRIM
GND
RTUNE
CO
CTUNE
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, 3, 4
and 5. Tables 2 and 4 show the recommended values of R_TUNE and C_TUNE for different values of ceramic output
capacitors up to 470uF that might be needed for an application to meet output ripple and noise requirements for
5Vin and 3.3Vin respectively. 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. Tables 3 and 5 list 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 1.5A to 3A step change
(50% of full load), with an input voltage of 5Vin and 3.3Vin respectively.
Please contact your Bel Power technical representative to obtain more details of this feature as well as for
guidelines on how to select the right value of external R-C to tune the module for best transient performance and
stable operation for other output capacitance values or input voltages other than 3.3 or 5V.
Bel Fuse Inc. 206 Van Vorst Street, Jersey City, NJ 07302 • Tel [phone] • Fax [phone] • www.belfuse.com
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