GE Industrial Solutions NQR002A0X4 - Manual (Page 15)

Preliminary Data Sheet
February 28, 2012 NQR002A0X4: Non-Isolated DC-DC Power Modules
3 – 14Vdc input; 0.6Vdc to 5.5Vdc Output; 2A output current
LINEAGE POWER 15
Feature Descriptions (continued)
Figure 9. Circuit Configuration for margining
Output voltage.
Monotonic Start-up and Shutdown
The NQR002A0X4 2A modules have monotonic start-up
and shutdown behavior for any combination of rated
input voltage, output current and operating temperature
range.
Tunable Loop TM
The NQR002A0X4 2A modules have a new feature that
optimizes transient response of the module called
Tunable Loop
TM . External capacitors are usually added
to improve output voltage transient response due to
load current changes. Sensitive loads may also require
additional output capacitance to reduce output ripple
and noise. 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.
To use the additional external capacitors in an optimal
manner, the Tunable Loop
TM feature allows the loop to
be tuned externally by connecting a series R-C between
the VOUT and TRIM pins of the module, as shown in
Fig. 10. This R-C allows the user to externally adjust
the voltage loop feedback compensation of the module
to match the filter network connected to the output of
the module.
Recommended values of R
TUNE
and C
TUNE
are given in
Tables 2 and 3. Table 2 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 1A to 2A step change (50% of full load),
with an input voltage of 12V. Table 3 shows the
recommended values of R
TUNE
and C
TUNE
for different
values of ceramic output capacitors up to TBD, again for
an input voltage of 12V. The value of R
TUNE
should
never be lower than the values shown in Tables 3 and
4. 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.
Figure. 10. Circuit diagram showing connection of
R
TUME
and C
TUNE
to tune the control loop of the
module.
Table 2. Recommended values of R
TUNE
and C
TUNE
to
obtain transient deviation of 2% of Vout for a 1A
step load with Vin=12V.
TBD
Table 3. General recommended values of of R
TUNE
and C
TUNE
for Vin=12V and various external ceramic
capacitor combinations.
TBD
Vo
MODULE
GND
Trim
Q1
Rtrim
Rmargin-up
Q2
Rmargin-down
MODULE
TRIM
VOUT
GND
RTUNE
CTUNE
RTrim