GE Industrial Solutions 12V MicroTLynx 12A - Manual (Page 18)

GE
Data Sheet
12V MicroTLynx TM 12A: Non-Isolated DC-DC Power Modules
4.5Vdc –14Vdc input; 0.69Vdc to 5.5Vdc output; 12A Output Current
May 2, 2013 ©2013 General Electric Company. All rights reserved. Page 18
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 in Fig. 48. This R-C allows the user to
externally adjust the voltage loop feedback compensation 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 940 F 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
Figure. 48. Circuit diagram showing connection of R
TUME
and
C
TUNE
to tune the control loop 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 6A to 12A step
change (50% of full load), with an input voltage of 12V.
Please contact your GE 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 12V.
Table 2. General recommended values of of R
TUNE
and C
TUNE
for Vin=12V and various external ceramic capacitor
combinations.
Co 1x47 μF 2x47μF 4x47μF 10x47μF 20x47μF
R
TUNE
470 270 150 150 150
C
TUNE
1000pF 3300pF 4700pF 8200pF 12nF
Table 3. Recommended values of R
TUNE
and C
TUNE
to obtain
transient deviation of 2% of Vout for a 6A step load with
Vin=12V.
Vo 5V 3.3V 2.5V 1.8V 1.2V 0.69V
Co 4x47μF
1x47 μF
+
330 μF
Polymer
2x47 μF
+
330 μF
Polymer
6x47 μF +
330 μF
Polymer
6x47 μF +
2x330 μF
Polymer
4x47 μF +
6x330 μF
Polymer
R
TUNE 270 220 220 220 150 150
C
TUNE 3300pF 4700pF 6800pF 18nF 33nF 100nF
ΔV 91mV 60mV 47mV 35mV 23mV 12mV
MODULE
VOUT
SENSE
TRIM
GND
RTUNE
CTUNE
RTrim
C O