A
12 Watt LV Dual Series DC/DC Converters
2401 Stanwell Drive Concord, California 94520 Ph: 925/687-4411 or 800/542-3355 Fax: 925/687-3333 www.calex.com Email: sales@calex.com
1
eco# 020903-3, eco# 041007-1
Features
Universal 3.5 to 16 Volt Input Range
Up to 12 Watts of PCB Mounted Power
Efficiencies to 80%
Fully Isolated, Filtered Design
Low Noise Outputs, < 50 mV P-P
Very Low I/O Capacitance, 375 pF Typical
Water Washable Shielded Copper Case
5 Year Warranty
Description
The universal input of the LV dual series spans 3.5 to 16 volts.
This makes these converters ideal for 4.8 to 12 volt battery
and the more traditional 5 volt logic powered systems.
Coupled with this is the very low output noise of typically
less than 50 mV peak to peak. The noise is also fully specified
for RMS value and if even these impressive noise figures
aren't enough, our applications section shows a simple add
on circuit that can reduce the output noise to less than 20 mV
P-P.
Full isolation is provided to help cut ground loops in logic
powered systems that could create havoc with sensitive, high
precision analog circuitry.
No extra components or heatsinking are required for most
applications saving you design time and valuable PCB space.
12 Watt LV Dual Series Block Diagram
t
r
a
h
C
n
o
i
t
c
e
l
e
S
l
e
d
o
M
e
g
n
a
R
t
u
p
n
I
C
D
V
t
u
p
t
u
O
C
D
V
t
u
p
t
u
O
A
m
n
i
M
x
a
M
V
L
0
0
0
1
.
5
D
5
5
.
3
6
1
5
0
0
0
1
V
L
0
0
5
.
2
1
D
5
5
.
3
6
1
2
1
0
0
5
V
L
0
0
4
.
5
1
D
5
5
.
3
6
1
5
1
0
0
4
What all this means to you is a tighter, more compact
overall system that has the capability of being universally
powered. Full application information is provided to make
integrating this supply in your system a snap.
Remote output voltage trim and ON/OFF functions are also
included.
Other input and output voltage combinations may be
factory ordered, contact CALEX applications engineering at
1-800-542-3355 for more information.
A
12 Watt LV Dual Series DC/DC Converters
2401 Stanwell Drive Concord, California 94520 Ph: 925/687-4411 or 800/542-3355 Fax: 925/687-3333 www.calex.com Email: sales@calex.com
2
eco# 020903-3, eco# 041007-1
NOTES
*
All parameters measured at Tc=25C, nominal input voltage
and full rated load unless otherwise noted. Refer to the
CALEX Application Notes for the definition of terms,
measurement circuits and other information.
(1)
Reduced output power available below 9 volts input. See
applications section for more information.
(2)
To determine the correct fuse size, see CALEX Application
Notes.
(3)
No minimum load required for operation . Reduced output
power is available below 9 volts input. See applications section.
(4)
Load regulation is defined for loading/unloading both outputs
simultaneously. Load range is 25 to 100%.
(5)
Cross regulation is defined for loading/unloading one output
while the other output is kept at full load. Load range is
25 to 100%.
(6)
Short term stability is specified after a 30 minute warmup
at full load, constant line and recording the drift over a 24
hour period.
(7)
The transient response is specified as the time required to settle
from a 50 to 75 % step load change (rise time of step = 2 Sec)
to a 1% error band.
(8)
Dynamic response is the peak overshoot voltage during the
transient response time as defined in note 7 above.
(9)
Noise is measured per CALEX Application Notes. Measurement
bandwidth is 0-20 MHz for peak-peak measurements, 10 kHz to
1 MHz for RMS measurements. Output noise is measured with
a 0.01F ceramic in parallel with a 1F/35V Tantalum capacitor
located 1" away from the converter to simulate your PCB's
standard decoupling.
(10) See the applications section for more information on applying
the ON/OFF pin.
(11) The Case is tied to the CMN output pin.
(12) The functional temperature range is intended to give an additional
data point for use in evaluating this power supply. At the
low functional temperature the power supply will function with
no side effects, however, sustained operation at the high
functional temperature will reduce expected operational life.
The data sheet specifications are not guaranteed over the
functional temperature range.
(13) The case thermal impedance is specified as the case
temperature rise over ambient per package watt dissipated.
(14) Specifications subject to change without notice.
(15) Water Washability - Calex DC/DC converters are designed to
withstand most solder/wash processes. Careful attention should
be used when assessing the applicability in your specific
manufacturing process. Converters are not hermetically sealed.
*
s
r
e
t
e
m
a
r
a
P
t
u
p
n
I
l
e
d
o
M
V
L
0
0
0
1
.
5
D
5
V
L
0
0
5
.
2
1
D
5
V
L
0
0
4
.
5
1
D
5
s
t
i
n
U
)
1
(
e
g
n
a
R
e
g
a
t
l
o
V
N
I
M
X
A
M
5
.
3
6
1
C
D
V
d
a
o
L
o
N
t
n
e
r
r
u
C
t
u
p
n
I
d
a
o
L
%
5
7
P
Y
T
P
Y
T
4
1
0
0
3
2
3
2
0
5
6
2
8
2
0
8
6
2
A
m
y
c
n
e
u
q
e
r
F
g
n
i
h
c
t
i
w
S
P
Y
T
0
6
z
H
k
,
e
g
a
t
l
o
v
r
e
v
O
t
u
p
n
I
m
u
m
i
x
a
M
m
u
m
i
x
a
M
s
m
0
0
1
X
A
M
0
2
C
D
V
,
e
m
i
T
n
o
-
n
r
u
T
r
o
r
r
E
t
u
p
t
u
O
%
1
P
Y
T
0
1
s
m
e
s
u
F
d
e
d
n
e
m
m
o
c
e
R
)
2
(
S
P
M
A
*
s
r
e
t
e
m
a
r
a
P
t
u
p
t
u
O
l
e
d
o
M
V
L
0
0
0
1
.
5
D
5
V
L
0
0
5
.
2
1
D
5
V
L
0
0
4
.
5
1
D
5
s
t
i
n
U
e
g
a
t
l
o
V
t
u
p
t
u
O
5
2
1
5
1
C
D
V
y
c
a
r
u
c
c
A
e
g
a
t
l
o
V
t
u
p
t
u
O
N
I
M
P
Y
T
X
A
M
5
9
.
4
0
0
.
5
5
0
.
5
0
8
8
.
1
1
0
0
0
.
2
1
0
2
1
.
2
1
0
5
8
.
4
1
0
0
0
.
5
1
0
5
1
.
5
1
C
D
V
e
c
n
a
l
a
B
t
u
p
t
u
O
d
a
o
L
ll
u
F
,
t
u
p
t
u
O
s
u
n
i
M
o
t
s
u
l
P
P
Y
T
X
A
M
1
.
0
<
0
.
1
%
)
3
(
e
g
n
a
R
d
a
o
L
d
e
t
a
R
N
I
M
X
A
M
0
0
0
0
1
0
0
0
5
0
0
0
4
A
m
)
4
(
n
o
i
t
a
l
u
g
e
R
d
a
o
L
C
D
V
2
1
=
n
i
V
P
Y
T
X
A
M
1
.
0
7
.
0
1
.
0
5
.
0
1
.
0
5
.
0
%
)
5
(
n
o
i
t
a
l
u
g
e
R
s
s
o
r
C
P
Y
T
5
.
2
5
.
1
5
.
1
%
n
o
i
t
a
l
u
g
e
R
e
n
i
L
C
D
V
x
a
M
-
n
i
M
=
n
i
V
P
Y
T
X
A
M
1
.
0
2
.
0
%
)
6
(
y
t
il
i
b
a
t
S
m
r
e
T
t
r
o
h
S
P
Y
T
5
0
.
0
<
s
r
H
4
2
/
%
y
t
il
i
b
a
t
S
m
r
e
T
g
n
o
L
P
Y
T
1
.
0
<
s
r
H
k
/
%
)
7
(
e
s
n
o
p
s
e
R
t
n
e
i
s
n
a
r
T
C
D
V
2
1
=
n
i
V
P
Y
T
0
0
2
0
5
0
5
s
)
8
(
e
s
n
o
p
s
e
R
c
i
m
a
n
y
D
P
Y
T
0
0
1
0
2
1
0
5
1
k
a
e
p
V
m
)
9
(
k
a
e
P
-
k
a
e
P
,
e
s
i
o
N
P
Y
T
0
2
1
0
5
0
5
P
-
P
V
m
w
b
z
H
M
1
-
1
0
.
0
,
e
s
i
o
N
S
M
R
P
Y
T
5
3
5
1
5
1
S
M
R
V
m
t
n
e
i
c
i
f
f
e
o
C
e
r
u
t
a
r
e
p
m
e
T
P
Y
T
X
A
M
0
5
0
5
1
C
/
m
p
p
o
t
n
o
i
t
c
e
t
o
r
P
t
i
u
c
r
i
C
t
r
o
h
S
s
t
u
p
t
u
O
ll
a
r
o
f
n
o
m
m
o
C
t
i
m
i
L
t
n
e
r
r
u
C
m
r
e
T
t
r
o
h
S
A
12 Watt LV Dual Series DC/DC Converters
2401 Stanwell Drive Concord, California 94520 Ph: 925/687-4411 or 800/542-3355 Fax: 925/687-3333 www.calex.com Email: sales@calex.com
3
eco# 020903-3, eco# 041007-1
n
i
P
n
o
i
t
c
n
u
F
1
F
F
O
/
N
O
2
T
U
P
N
I
-
3
T
U
P
N
I
+
4
T
U
P
T
U
O
+
5
N
M
C
6
T
U
P
T
U
O
-
7
M
I
R
T
BOTTOM VIEW
SIDE VIEW
Mechanical tolerances unless otherwise noted:
X.XX dimensions: 0.020 inches
X.XXX dimensions: 0.005 inches
*
s
n
o
i
t
a
c
i
f
i
c
e
p
S
l
a
r
e
n
e
G
s
l
e
d
o
M
l
l
A
s
t
i
n
U
n
o
i
t
c
n
u
F
F
F
O
/
N
O
l
e
v
e
L
c
i
g
o
L
F
F
O
)
0
1
(
t
u
p
n
I
-
o
t
n
i
P
e
i
T
r
o
X
A
M
4
.
0
<
C
D
V
e
g
a
t
l
o
V
t
i
u
c
r
i
C
n
e
p
O
P
Y
T
4
.
1
C
D
V
e
c
n
a
t
s
i
s
e
R
t
u
p
n
I
P
Y
T
2
s
m
h
o
k
t
n
e
r
r
u
C
e
l
d
I
r
e
t
r
e
v
n
o
C
w
o
L
n
i
P
F
F
O
/
N
O
P
Y
T
6
A
m
)
1
1
(
n
o
i
t
a
l
o
s
I
e
g
a
t
l
o
V
n
o
i
t
a
l
o
s
I
t
u
p
t
u
O
o
t
t
u
p
n
I
e
g
a
k
a
e
L
A
0
1
N
I
M
0
0
7
C
D
V
t
u
p
t
u
O
o
t
t
u
p
n
I
e
c
n
a
t
i
c
a
p
a
C
P
Y
T
5
7
3
F
p
n
o
i
t
c
n
u
F
m
i
r
T
t
u
p
t
u
O
e
g
n
a
R
m
i
r
T
N
I
M
0
1
%
e
c
n
a
t
s
i
s
e
R
t
u
p
n
I
N
I
M
0
1
s
m
h
o
k
l
a
t
n
e
m
n
o
r
i
v
n
E
e
g
n
a
R
g
n
i
t
a
r
e
p
O
e
s
a
C
g
n
i
t
a
r
e
D
o
N
N
I
M
X
A
M
0
4
-
5
8
C
)
2
1
(
e
g
n
a
R
l
a
n
o
i
t
c
n
u
F
e
s
a
C
N
I
M
X
A
M
0
5
-
0
0
1
C
e
g
n
a
R
e
g
a
r
o
t
S
N
I
M
X
A
M
5
5
-
5
0
1
C
)
3
1
(
e
c
n
a
d
e
p
m
I
l
a
m
r
e
h
T
P
Y
T
5
.
9
t
t
a
W
/
C
l
a
r
e
n
e
G
t
h
g
i
e
W
t
i
n
U
P
Y
T
3
.
2
z
o
t
i
K
g
n
i
t
n
u
o
M
s
i
s
s
a
h
C
8
S
M
A
12 Watt LV Dual Series DC/DC Converters
2401 Stanwell Drive Concord, California 94520 Ph: 925/687-4411 or 800/542-3355 Fax: 925/687-3333 www.calex.com Email: sales@calex.com
4
eco# 020903-3, eco# 041007-1
Applications Information
You truly get what you pay for in a CALEX converter, a
complete system oriented and specified DC/DC converter -
no surprises, no external noise circuits needed, no heatsinking
problems, just "plug and play".
The LV Dual series like all CALEX converters carries the
full 5 year CALEX no hassle warranty. We can offer a five year
warranty where others can't because with CALEX it's rarely
needed.
General Information
The universal 3.5 to 16 volt input of the LV Dual series allows
you to specify your system for operation from any 5 volt logic
supply or a 4.8 to 12 volt nominal battery input.
The series is also mindful of battery operation for industrial,
medical, control and remote data collection applications. The
remote ON/OFF pin places the converter in a very low power
mode that draws typically less than 6 mA from the input
source.
Noise has also achieved new lows in this single design,
while the industry standard is to specify output noise as 1 to
5% peak to peak typical with no mention of measurement
bandwidth. The LV converters achieve noise levels of less
than 50 mV peak to peak and are fully specified and tested to
a wide bandwidth of 0-20 MHz.
Five sided shielding is standard along with specified
operation over the full industrial temperature range of -40 to
+85 C case temperature.
Applying The Input
Figure 1 shows the recommended input connections for the
LV Single DC/DC converter. A fuse is recommended to
protect the input circuit and should not be omitted. The fuse
serves to prevent unlimited current from flowing in the case of
a catastrophic system failure.
Figure 1.
If the source impedance driving the LV Converter is more than about
0.05 ohms the optional capacitor C2 may be required (See text for
more information). Optional transient protector diode D1 may be
used if desired for added protection. The fuse serves as a cata-
strophic failure protector and should not be omitted.
*
*
ON/OFF MAY BE LEFT FLOATING IF NOT USED
When using the LV Dual be sure that the impedance at the
input to the converter is less than 0.05 ohms from DC to about
100 kHz, this is usually not a problem in battery powered
systems when the converter is connected directly to the
battery. If the converter is located more than about 1 inch from
the input source an added capacitor may be required directly
at the input pins for proper operation.
The maximum permissible source impedance is a function
of output power and line voltage. The impedance can be
higher when operating at less than full power. The minimum
impedance is required when operating with a 9 volt input at full
load. The impedance reduces as the input voltage is raised or
lowered or the power is reduced. In general you should keep
the peak to peak voltage measured across the input pins less
than 0.15 volts peak to peak (not including the high frequency
spikes) for maximum converter performance and life.
There is no lower limit on the allowed source impedance,
it can be any physically realizable value, even approaching 0.
If the source impedance is too large in your system you
should choose an external input capacitor as detailed below.
Picking An External Input Capacitor
If an input capacitor is needed at the input to the converter it
must be sized correctly for proper converter operation. The
curve "RMS Input Current Vs Line Input" shows the RMS
ripple current that the input capacitor must withstand with
varying loading conditions and input voltages.
Several system tradeoffs must be made for each particular
system application to correctly size the input capacitor.
The probable result of undersizing the capacitor is increased
self heating, shortening it's life. Oversizing the capacitor can
have a negative effect on your products cost and size,
although this kind of overdesign does not result in shorter life
of any components.
There is no one optimum value for the input capacitor. The
size and capacity depend on the following factors:
1)
Expected ambient temperature and your temperature
derating guidelines.
2)
Your ripple current derating guidelines.
3)
The maximum anticipated load on the converter.
4)
The input operating voltage, both nominal and
excursions.
5)
The statistical probability that your system will spend a
significant time at any worst case extreme.
Factors 1 and 2 depend on your system design guidelines.
These can range from 50 to 100% of the manufacturers listed
maximum rating, although the usual derating factor applied is
about 70%. 70% derating means if the manufacturer rated the
capacitor at 1 A RMS you would not use it over 0.7 A RMS in
your circuit.
Factors 3 and 4 realistically determine the worst case ripple
current rating required for the capacitor along with the RMS
ripple current curve.
Factor 5 is not easy to quantify. At CALEX we can make no
A
12 Watt LV Dual Series DC/DC Converters
2401 Stanwell Drive Concord, California 94520 Ph: 925/687-4411 or 800/542-3355 Fax: 925/687-3333 www.calex.com Email: sales@calex.com
5
eco# 020903-3, eco# 041007-1
Startup Current Demand
Because the LV Dual appears as a constant power load to
your source and operation starts at about 3 volts, you should
be sure that your source can supply the required current at low
voltages when starting. If this presents a problem the ON/OFF
pin and a simple voltage detector (comparator) may be used
to prevent startup until some higher steady state voltage.
Generally this is not a problem with battery powered
circuits and only appears when the LV Dual is powered by
marginally sized 5 or 12 volt linear supplies that can't supply
the required startup current. See the"Input Current Vs. Line
Input" curve for the low voltage current requirements of the LV
Dual.
Very Low Noise Input Circuit
Figure 2 shows a very low noise input circuit that may be used
with the converters. This circuit will reduce the input reflected
ripple current to less than 20 mA RMS (Vin = 5 V, 10 kHz to
1 MHz bw). See the discussion above for the optimum
selection of C2.
Figure 2.
This circuit will reduce the input reflected ripple current to less than
20 mA RMS. See the discussion in the text for help on the optimum
selection of C2. L1 should be sized to handle the maximum input
current at your lowest operating voltage and maximum expected
output power.
Suggested Capacitor Sources
These capacitors may be used to lower your sources input
impedance at the input of the converter. These capacitors will
work for 100% load, worst case input voltage and ambient
temperature extremes. They however, may be oversized for
your exact usage, see "Picking An External Input Capacitor"
above for more information. You may also use several smaller
capacitors in parallel to achieve the same ripple current rating.
This may save space in some systems.
United Chemi-Con SXE, RXC, RZ and RZA series
Suggested Part:
SXE025VB820M12.5X20LL
820F, 25V, 105C Rated
ESR=0.085 ohms
Allowable Ripple at 85C = 1.96 A
L1 =
10 H
C1 =
10 F / 25V, TANTALUM
C2 =
SEE TEXT
assumptions about a customers system so we leave to you
the decision of how you define how big is big enough. Suitable
capacitors for use at the input of the converter are given at the
end of this section.
Nichicon
PR and PF series
Suggested Part:
UPR1E222MRH
2200F, 25V, 105C Rated
ESR=0.053 ohms
Allowable Ripple at 85C = 1.98 A
Panasonic
HFG and HFQ Series
Suggested Part:
ECEA1EFE332L
3300F, 25V, 105C Rated
ESR=0.045 ohms
Allowable Ripple at 85 C = 1.94 A
Remote ON/OFF Pin Operation
The remote ON/OFF pin may be left floating if this function is
not used. The best way to drive this pin is with an open
collector/drain or relay contact.
Do not drive this input from a logic gate directly. The ON/
OFF pin must be left floating to turn the converter on and
insure proper operation. This input is noise sensitive so it
should not be routed all over your PCB.
When the ON/OFF pin is pulled low with respect to the -
Input, the converter is placed in a low power drain state. The
ON/OFF pin turns the converter off while keeping the input
bulk capacitors fully charged, this prevents the large inrush
current spike that occurs when the +input pin is opened and
closed.
The ON/OFF pin should never be pulled more that 0.3 volts
below the -Input or have a voltage of greater than +2 volts
applied to it.
Applying The Output
Figure 3 shows typical output connections for the LV Dual. In
most applications no external output capacitance will be
necessary. Only your normal 1 to 10 uF tantalum and 0.001
to 0.1 F ceramic bypass capacitors sprinkled around your
circuit as needed locally are required. Do not add extra output
capacitance and cost to your circuit "Just Because".
If you feel you must add external output capacitance, do
not use the lowest ESR, biggest value capacitor that you can
find! This can only lead to reduced system performance or
oscillation. See our application note "Understanding Output
Impedance For Optimum Decoupling" for more information.
Output Power
The available output power of the LV Dual is reduced when
operating below 9 and 4.6 volts. See the "Low Voltage Power"
curve for more information. In general, from 9 to 16 volts full
power is available from the LV Dual. From 4.6 to 9 volts input
the available output power is 75% of the full load value. Below
4.6 volts the output power is linearly derated from 75% at 4.6
volts to 40% at 3.5 volts. For example a LV Dual is capable of
providing 4.8 watts of output power at 3.5 volts input.
Table 1 summarizes the output current available versus
input voltage.
A
12 Watt LV Dual Series DC/DC Converters
2401 Stanwell Drive Concord, California 94520 Ph: 925/687-4411 or 800/542-3355 Fax: 925/687-3333 www.calex.com Email: sales@calex.com
6
eco# 020903-3, eco# 041007-1
Figure 3.
The LV Dual may be directly connected to your load without any
external components required for most applications. The outputs
may also be used in single ended mode. Transient overvoltage
diodes may be added for extra protection against output faults or if
the input has the possibility of being shorted to the loads.
*
*
TRIM MAY BE LEFT FLOATING IF NOT USED
Note: The maximum current is linearly derated between the
break points. See the output power graph for more information.
Ultra Low Noise Output Circuit
The circuit shown in figure 4 can be used to reduce the output
noise to below 20 mV P-P over a 20 MHz bandwidth. Size
inductor L1 appropriately for the maximum expected load
current. All of the ground connections must be as short as
possible back to the CMN pin. The filter should be placed as
close to the LV Dual as possible, even if your load is at some
distance from the converter.
Figure 4.
This circuit can reduce the output noise to below 15 mV P-P over a
20 MHz bandwidth. Size inductor L1 appropriately for the maximum
expected load current. All of the ground connections must be as
short as possible back to the CMN pin.
L1 =
10 H
C1 =
100 F / 25V, ALUMINUM
C2 =
10 F / 25V, TANTALUM
1
e
l
b
a
T
l
e
d
o
M
t
n
e
r
r
u
C
t
u
p
t
u
O
m
u
m
i
x
a
M
/
e
g
a
t
l
o
V
t
u
p
n
I
V
5
.
3
V
6
.
4
V
9
V
L
0
0
0
1
.
5
D
5
A
m
0
0
4
A
m
0
5
7
A
m
0
0
0
1
V
L
0
0
5
.
2
1
D
5
A
m
0
0
2
A
m
5
7
3
A
m
0
0
5
V
L
0
0
4
.
5
1
D
5
A
m
0
6
1
A
m
0
0
3
A
m
0
0
4
.
Operation With Very Light Loads
Dynamic response of the LV Dual will degrade when the unit
is operated with less than 25% of full rated power.
Output Trimming
The trim pin may be used to adjust the outputs by up to 10
% from the nominal factory setting. The trim may be used to
adjust for system wiring voltage drops. Figure 5 shows the
proper connections to use the trim pin. If output trimming is not
desired the trim pin may be safely left floating.
Trimming the output up reduces the output current
proportionally to keep the maximum power constant. Output
current is not increased over the listed maximum when
trimming the output voltage down.
Full up trim may not be achievable at minimum input
voltage and full rated load.
Non Standard Output Voltages
The LV Duals will typically trim much lower than the -10%
specified. This allows the 12 and 15 volt LV's to be trimmed
lower than specified for RF or other special applications.
The 5 volt LV's can be typically trimmed over a range of 3.8
to 5.6 volts. The 12 volt LV's can be typically trimmed over a
range of 6.4 to 13.3 volts. The 15 volt LV's can be typically
trimmed over a range of 6.7 to 16.9 volts.
The dual outputs may also be used in a single ended mode
as shown in figure 3 to get 10, 24 or 30 volts of output at the
full rated power levels (i.e. 1A, 0.5A or 0.4A). To use the single
ended mode just connect your load to the + and - Output pins
and leave the CMN pin floating. Trimming of the outputs may
also be done while using the single ended mode.
Grounding
The input and output sections are fully floating from each
other. They may be operated fully floating or with a common
ground. If the input and output sections are connected either
directly at the converter or at some remote location from the
converter it is suggested that a 1 to 10 F, 0.5 to 5 ohm ESR
Figure 5.
Output trimming may be accomplished by using a Dual fixed resistor
or a trimpot as shown. When using fixed resistors the values may
range from 0 to infinity ohms. See the text for more information on
output power when trimming. The trimpot should be approximately
20K ohms.
A
12 Watt LV Dual Series DC/DC Converters
2401 Stanwell Drive Concord, California 94520 Ph: 925/687-4411 or 800/542-3355 Fax: 925/687-3333 www.calex.com Email: sales@calex.com
7
eco# 020903-3, eco# 041007-1
capacitor bypass be used directly at the converters output
pins. These capacitors prevent any common mode switching
currents from showing up at the converters output as normal
mode output noise. See "Applying the Output" for more
information on selecting output capacitors.
Also see the CALEX application note "Dealing With
Common Mode Noise" for more information on using common
grounds.
Case Grounding
The copper case serves not only as a heat sink but also as a
EMI shield. The 0.017 inch thick case provides >15 dB of
absorption loss to both electric and magnetic fields at 60 kHz,
while at the same time providing 20 to 40 % better heat sinking
over competitive thin steel, aluminum or plastic designs.
The case shield is tied to the CMN output pin. This
connection is shown on the block diagram. The case is
floating from the input sections. The input is coupled to the
outputs only by the low 375 pF of isolation capacitance. This
low I/O capacitance insures that any AC common mode noise
on the inputs is not coupled to your output circuits.
Compare this isolation to the more usual 1000 - 2000 pF
found on competitive designs and you will see that CALEX
provides the very best DC and AC isolation available. After all,
you are buying an isolated DC/DC to cut ground loops. Don't
let the isolation capacitance add them back in.
Temperature Derating
The LV Dual series can operate up to 85C case temperature
without derating. Case temperature may be roughly calculated
from ambient by knowing that the case temperature rise is
approximately 9.5C per package watt dissipated.
For example: If a 12 volt output converter is delivering 9
Watts with a 12 volt input, at what ambient could it expect to
run with no moving air and no extra heatsinking?
Efficiency of the converter is approximately 76% at 9 watts
of output power, this leads to an input power of about 12
Watts. The case temperature rise would be 12 - 9 Watts or 3
Watts
9.5 = 28.5C. This number is subtracted from the
maximum case temperature of 85C to get: 56.5C.
This example calculation is for an LV Dual without any
extra heat sinking or appreciable air flow. Both of these factors
can greatly effect the maximum ambient temperature (see
below). Exact efficiency depends on input line and load
conditions, check the efficiency curves for exact information.
This is a rough approximation to the maximum ambient
temperature. Because of the difficulty of defining ambient
temperature and the possibility that the loads dissipation may
actually increase the local ambient temperature significantly,
these calculations should be verified by actual measurement
before committing to a production design.
Remember, it is the system designers responsibility to be
sure that the case temperature of the LV Dual does not
exceed 85 C for maximum reliability in operation.
Typical Performance (Tc=25C, Vin=Nom VDC, Rated Load).
0
10
20
30
40
50
60
70
80
90
100
LOAD (%)
55
60
65
70
75
80
85
EFFICIENCY (%)
EFFICIENCY Vs. LOAD
LINE = 5VDC
LINE = 16VDC
4
6
8
10
12
14
16
LINE INPUT(VOLTS)
50
55
60
65
70
75
80
85
EFFICIENCY(%)
EFFICIENCY Vs. LINE INPUT VOLTAGE
100% FULL LOAD
50% FULL LOAD
0
2
4
6
8
10
12
14
16
LINE INPUT (VOLTS)
0
1
2
3
4
5
6
INPUT CURRENT (AMPS)
INPUT CURRENT Vs. LINE INPUT VOLTAGE
100% LOAD
50% LOAD
3
5
7
9
11
13
15
17
LINE INPUT (VDC)
0.0
0.5
1.0
1.5
2.0
2.5
RMS INPUT CURRENT (AMPS)
RMS INPUT CURRENT Vs LINE INPUT
100% LOAD
75% LOAD
40% LOAD
3
5
7
9
11
13
15
17
LINE INPUT (VDC)
40
50
60
70
80
90
100
110
% AVAILABLE POWER
POWER DERATING
PDF 
ZIP