GE Industrial Solutions 2A DLynx - Manual (Page 16)

GE Energy
Datasheet
2A DLynx TM : Non-Isolated DC-DC Power Modules
3Vdc –14Vdc input; 0.6Vdc to 5.5Vdc output; 2A Output Current
June 24, 2013 ©2012 General Electric Company. All rights reserved. Page 16
Monotonic Start-up and Shutdown
The 12V DLynx TM 2A modules have monotonic start-up and
shutdown behavior for any combination of rated input voltage,
output current and operating temperature range.
Startup into Pre-biased Output
The 12V DLynx TM 2A modules can start into a prebiased output
as long as the prebias voltage is 0.5V less than the set output
voltage.
Power Good
The 12V DLynx TM 2A 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 overtemperature, overcurrent
or loss of regulation occurs that would result in the output
voltage going ±12.5% outside the setpoint value. The PGOOD
terminal should be connected through a pullup resistor
(suggested value 100K
Ω) to a source of 5VDC or lower.
Tunable Loop TM
The 12V DLynx TM 2A 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 (see
Fig. 42) 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. 48. This R-C allows the user to
externally adjust the voltage loop feedback compensation of
the module.
MODULE
VOUT
SENSE
TRIM
GND
RTUNE
CTUNE
RTrim
C O
Figure. 48. 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 and
3. Table 2 shows 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. 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 3,4 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 1A to 2A step
change (50% of full load), for input voltages of 12V, 5V
and 3.3V respectively.
Please contact your GE Energy 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/5V/3.3V and various external
ceramic capacitor combinations.
Co 1x47 μF 2x47μF 3x47μF 4x47μF 10x47μF
R
TUNE
220 150 100 100 100
C
TUNE
3900pF 10nF 18nF 18nF 22nF
Table 3. Recommended values of R
TUNE
and C
TUNE
to
obtain transient deviation of ≤2% of Vout for a 1A step
load with Vin=12V
Vo 5V 3.3V 2.5V 1.8V 1.2V 0.6V
Co 1x22μF 1x47μF 2x47μF 2x47μF 3x47μF 330μF
Polymer
R
TUNE
220 220 150 150 100 100
C
TUNE
2200pF 3900pF 10nF 10nF 18nF 68nF
ΔV 81mV 61mV 35mV 34mV 23mV 12mV
Table 4. Recommended values of R
TUNE
and C
TUNE
to
obtain transient deviation of ≤2% of Vout for a 1A step
load with Vin=5V
Vo 3.3V 2.5V 1.8V 1.2V 0.6V
Co 1x47μF 2x47μF 2x47μF 3x47μF 330μF
Polymer
R
TUNE
220 150 150 100 100
C
TUNE
3900pF 10nF 10nF 18nF 68nF
ΔV 62mV 35mV 34mV 23mV 12mV