GE Industrial Solutions 20A Analog MicroDLynx - Manual (Page 12)

GE
Data Sheet
20A Analog MicroDLynx TM : Non-Isolated DC-DC Power Modules
3Vdc –14.4Vdc input; 0.45Vdc to 5.5Vdc output; 20A Output Current
April 24, 2013 ©2012 General Electric Company. All rights reserved. Page 12
Design Considerations
Input Filtering
The 20A Analog MicroDLynx 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, ceramic capacitors are
recommended at the input of the module. Figure 37 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.
Inpu
t R
ipp
le
Vo
ltag
e
(m
Vp
-p)
Output Voltage (Vdc)
Figure 37. 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
These modules are designed for low output ripple voltage
and will meet the maximum output ripple specification with
0.1 µF ceramic and 2x47 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 20A. 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 2x47 µF, 4x47 µF or 6x47 µF
ceramic capacitors at the output (20A 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 UDT020A0X series were tested using an external
Littelfuse 456 series fast-acting fuse rated at 30 A, 100 Vdc
in the ungrounded input.
0
50
100
150
200
250
300
350
400
450
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
2x22uF
3x22 uF
0
10
20
30
40
50
60
70
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Ripp
le
(m
Vp
-p)
Output Voltage(Volts)
2x47uF Ext Cap
4x47uF Ext Cap
6x47uF Ext Cap
8x47uF Ext Cap