GE Industrial Solutions 12A Analog SlimLynx Open Frame - Manual (Page 16)

GE
Data Sheet
12A Analog SlimLynx TM Open Frame: Non-Isolated DC-DC Power Modules
3Vdc –14.4Vdc input; 0.6Vdc to 5.5Vdc output; 12A Output Current
February 19, 2014 ©2014 General Electric Corporation. All rights reserved. Page 16
Tunable Loop TM
The module has a 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
(see Figure 38) 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 VS+
and TRIM pins of the module, as shown in Fig. 47. This R-C
allows the user to externally adjust the voltage loop
feedback compensation of the module.
Figure. 47. Circuit diagram showing connection of R
TUME
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 Table 2. Table 2 shows
the recommended values of R
TUNE
and C
TUNE
for different
values of ceramic output capacitors up to 1000uF 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 6A to 12A step change (50% of full load),
with an input voltage of 12V.
Please contact your GE Critical 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.
Table 2. General recommended values of of R
TUNE
and C
TUNE
for Vin=12V and various external ceramic capacitor
combinations.
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 0.6V
Co
1x47uF
+ 330
μF
Polymer
1x47uF
+330 μF
Polymer
2x47 μF
+
330 μF
Polymer
1x47 μF +
2x330 μF
Polymer
3x47 μF +
3x330 μF
Polymer
1x47 μF +
11x330 μF
Polymer
R
TUNE 300 300 240 220 220 180
C
TUNE 2200pF 2200pF 3300pF 5600pF 12nF 47nF
ΔV 55mV 54mV 47mV 31mV 21mV 8mV
Note: The capacitors used in the Tunable Loop tables are
47 μF/4 mΩ ESR ceramic and 330 μF/12 mΩ ESR polymer
capacitors.
VS+
MODULE
SIG_GND
TRIM
VOUT
RTune
CTune
RTrim
CO
GND
Co 2x47 μF 4x47μF 6x47 μF 10x47μF 10x47 μF
R
TUNE 430 390 300 240 180
C
TUNE 390pF 1500pF 2700pF 3300pF 8200pF