GE Industrial Solutions NQR002A0X4 - Manual (Page 12)

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 12
Test Configurations
TO OSCILLOSCOPE CURRENT PROBE
L
TEST
1μH
B
A
TTE
R
Y
C S 1000μF
Electrolytic
E.S.R.<0.1 Ω
@ 20°C 100kHz
2x100μF
Tantalum
V IN (+)
COM
NOTE: Measure input reflected ripple current with a simulated
source inductance (L
TEST
) of 1μH. Capacitor C
S
offsets
possible battery impedance. Measure current as shown
above.
C
IN
Figure 1. Input Reflected Ripple Current Test Setup.
NOTE: All voltage measurements to be taken at the module
terminals, as shown above. If sockets are used then
Kelvin connections are required at the module terminals
to avoid measurement errors due to socket contact
resistance.
V O (+)
COM
1uF .
RESISTIVE
LOAD
SCOPE
COPPER STRIP
GROUND PLANE
10uF
Figure 2. Output Ripple and Noise Test Setup.
V
O
COM
V
IN
(+)
COM
R
LOAD
R contact R distribution
R contact R distribution R contact
R contact R distribution
R distribution
V
IN
V O
NOTE: All voltage measurements to be taken at the module
terminals, as shown above. If sockets are used then
Kelvin connections are required at the module terminals
to avoid measurement errors due to socket contact
resistance.
Figure 3. Output Voltage and Efficiency Test Setup.
η =
V
O
. I
O
V
IN
. I
IN
x 100 % Efficiency
Design Considerations
Input Filtering
The NQR002A0X4 2A module should be connected
to a low ac-impedance source. A highly inductive
source can affect the stability of the module. An input
capacitance must be placed directly adjacent to the
input pin of the module, to minimize input ripple
voltage and ensure module stability.
To minimize input voltage ripple, low-ESR ceramic or
polymer capacitors are recommended at the input of the
module. Figure 4 shows the input ripple voltage for
various output voltages at 2A of load current with 1x22
µF or 2x22 µF ceramic capacitors and an input of 12V.
Input
Ri
ppl
e
Vol
tage (mVp-
p
)
TBD
Output Voltage (Vdc)
Figure 4. Input ripple voltage for various output
voltages with 1x22 µF or 2x22 µF ceramic
capacitors at the input (2A load). Input voltage is
12V.
Output Filtering
The NQR002A0X4 2A modules are designed for low
output ripple voltage and will meet the maximum output
ripple specification with no external capacitors.
However, additional output filtering may be required by
the system designer for a number of reasons. First,
there may be a need to further reduce the output ripple
and noise of the module. Second, the dynamic
response characteristics may need to be customized to
a particular load step change.
To reduce the output ripple and improve the dynamic
response to a step load change, additional capacitance
at the output can be used. Low ESR ceramic and
polymer are recommended to improve the dynamic
response of the module. Figure 5 provides output ripple
information for different external capacitance values at
various Vo and for a load current of 2A. For stable
operation of the module, limit the capacitance to less
than the maximum output capacitance as specified in
the electrical specification table. Optimal performance
of the module can be achieved by using the Tunable
Loop
TM feature described later in this data sheet.