GE Industrial Solutions 12V TLynx 20A - Manual (Page 13)

GE
Data Sheet
12V TLynx TM 20A: Non-Isolated DC-DC Power Modules
4.5Vdc –14Vdc input; 0.69Vdc to 5.5Vdc output; 20A Output Current
May 2, 2013 ©2013 General Electric Company. All rights reserved. Page 13
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 37. 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.
Vo+
COM
0.1uF
RESISTIVE
LOAD
SCOPE USING
BNC SOCKET
COPPER STRIP
GROUND PLANE
10uF
Figure 38. 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 39. Output Voltage and Efficiency Test Setup.
η =
V
O
. I
O
V
IN
. I
IN
x 100 % Efficiency
Design Considerations
Input Filtering
The 12V TLynx TM 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 polymer and
ceramic capacitors are recommended at the input of the
module.
To minimize input voltage ripple, ceramic capacitors
are recommended at the input of the module. Figure
40 shows the input ripple voltage for various output
voltages at 20A of load current with 2x22 µF or 3x22
µF ceramic capacitors and an input of 12V.
In
put Ri
pple Vo
ltag
e (
m
Vp-p)
0
50
100
150
200
250
300
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
2x22uF
3x22 uF
Output Voltage (Vdc)
Figure 40. Input ripple voltage for various output
voltages with 2x22 µF or 3x22 µF ceramic
capacitors at the input (20A load). Input voltage is
12V.
Output Filtering
The 12V TLynx TM modules are designed for low output
ripple voltage and will meet the maximum output ripple
specification with 0.1 µF ceramic and 10 µF ceramic
capacitors at the output of the module. 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 polymer and ceramic
capacitors are recommended to improve the dynamic
response of the module. Figure 41 provides output ripple
information for different external capacitance values at
various Vo and for a full load current of 20A. For stable