GE Industrial Solutions 3A Digital PicoDLynx - Manual (Page 13)

GE
Data Sheet
3A Digital PicoDLynx TM : Non-Isolated DC-DC Power Modules
3Vdc –14.4Vdc input; 0.45Vdc to 5.5Vdc output; 3A Output Current
April 29, 2013 ©2012 General Electric Company. All rights reserved. Page 13
Design Considerations
Input Filtering
The 3A Digital PicoDLynx 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.
High frequency switching noise can be reduced by using
suitable decoupling ceramic caps. Refer to AN04-006 and
AN04-002 for more guidelines
To minimize input voltage ripple, ceramic capacitors are
recommended at the input of the module. Figure 37 shows
the input ripple voltage for various output voltages at 3A of
load current with 1x22 µF or 2x22 µF ceramic capacitors and
an input of 12V.
Figure 37. Input ripple voltage for various output voltages
with 2x22 µF or 3x22 µF ceramic capacitors at the input
(3A load). Input voltage is 12V.
Output Filtering
These modules are designed for low output ripple voltage and
will meet the maximum output ripple specification with 0.1 µF
ceramic and 22 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 38 provides output ripple information for
different external capacitance values at various Vo and a full
load current of 3A. 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.
Figure 38. Output ripple voltage for various output voltages
with external 1x10 µF, 1x22 µF, 1x47 µF or 2x47 µF ceramic
capacitors at the output (3A load). Input voltage is 12V.
Safety Considerations
For safety agency approval the power module must be
installed in compliance with the spacing and separation
requirements of the end-use safety agency standards, i.e., UL
60950-1 2nd, CSA C22.2 No. 60950-1-07, DIN EN 60950-1:2006
+ A11 (VDE0805 Teil 1 + A11):2009-11; EN 60950-1:2006 +
A11:2009-03.
For the converter output to be considered meeting the
requirements of safety extra-low voltage (SELV), the input must
meet SELV requirements. The power module has extra-low
voltage (ELV) outputs when all inputs are ELV.
The input to these units is to be provided with a fast acting
fuse with a maximum rating of 5 A in the positive input lead
.
An example of such a fuse is the ABC series by Littelfuse.
60
70
80
90
100
110
120
130
140
0.5 1.5 2.5 3.5 4.5
R
ip
p
le
(m
V
p
-p
)
Output Voltage(Volts)
1x22uF
2x22uF
0
10
20
30
40
50
0.5 1.5 2.5 3.5 4.5
Ri
p
p
le
(m
V
p
-p
)
Output Voltage(Volts)
1x10uF Ext Cap
1x22uF Ext Cap
1x47uF Ext Cap
2x47uF Ext Cap