GE Industrial Solutions TLynx - Manual (Page 16)

Data Sheet
August 13, 2013 TLynx TM : Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 20A output current
LINEAGE POWER 16
Tunable Loop TM
The TLynx TM series of modules have a new feature that
optimizes transient response of the module called the
Tunable Loop
TM .
External capacitors are usually added to the output of
the module for two reasons: to reduce output ripple and
noise (see Figures 36 and 37) 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 in Fig. 44. This R-C allows the user to externally
adjust the voltage loop feedback compensation of the
module.
Figure. 44. 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 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 1000 μF 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 Tables 2 and 4 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 10A to
20A step change (50% of full load), with an input
voltage of 5Vin and 3.3Vin respectively
Please contact your Lineage 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.
Table 2. General recommended values of of R
TUNE
and C
TUNE
for Vin=5V and various external ceramic
capacitor combinations.
Cext 1x47 μF 2x47μF 4x47μF 10x47μF 20x47μF
R
TUNE
47 47 47 33 22
C
TUNE
3300pF 6800pF 12nF 33nF 56nF
Table 3. Recommended values of R
TUNE
and C
TUNE
to
obtain transient deviation of 2% of Vout for a 10A
step load with Vin=5V.
Table 4. General recommended values of of R
TUNE
and C
TUNE
for Vin=3.3V and various external ceramic
capacitor combinations.
Cext 1x47 μF 2x47μF 4x47μF 10x47μF 20x47μF
R
TUNE
47 47 33 33 22
C
TUNE
6800pF 12nF 22nF 47nF 68nF
Table 5. Recommended values of R
TUNE
and C
TUNE
to
obtain transient deviation of 2% of Vout for a 10A
step load with Vin=3.3V.
Vout 3.3V 2.5V 1.8V 1.2V 0.6V
Cext
2x
330 μF
Polymer
Cap
2x47 μF +
2x330 μF
Polymer
Cap
3x330 μF
Polymer
Cap
4x47 μF
+ 4x330 μF
Polymer
Cap
10x330 μF
Polymer
Cap
R
TUNE
47 39 39 33 27
C
TUNE
39nF 47nF 150nF 220nF 330nF
ΔV 64mV 49mV 36mV 24mV 12mV
Vout 2.5V 1.8V 1.2V 0.6V
Cext
5x330 μF
Polymer
Cap
4x330 μF
Polymer
Cap
5x330 μF
Polymer
Cap
11x330 μF
Polymer
Cap
R
TUNE
27 27 27 22
C
TUNE
470nF 470nF 470nF 470nF
ΔV 48mV 36mV 24mV 12mV
MODULE
VOUT
SENSE
TRIM
GND
RTUNE
CTUNE
RTrim
C O