24D5.850WD [ETC]
Analog IC ; 模拟IC\n
| 型号： | 24D5.850WD |
| 厂家： | 
ETC |
| 描述： | Analog IC
|
| 文件： | 总6页 (文件大小：116K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
10 Watt WD Dual “Low Input” Series DC/DC Converters
Features
!
Universal 9 to 36 Volt Input Range.
!
Up to 10 Watts of PCB Mounted Power
!
Efficiencies to > 80%
!
Optional ON/OFF Control Pin
!
Fully Isolated, Filtered Design
!
Low Noise Outputs
!
Very Low I/O Capacitance, 350 pF Typical
!
Water Washable Shielded Copper Case
!
Five Year Warranty
Selection Chart
Input Range
VDC
Description
Output
mA
The universal input of the WD Dual series spans 9 to 36 volts.
This makes these converters ideal for 12, 24 and 28 volt
battery and process control applications.
Model
Power
W
Min
Max
VDC
24D5.850WD
24D12.400WD
24D15.320WD
9
9
9
36
36
36
±5
±850
±400
±320
9
Coupled with these features is a low output noise of
typically less than 80 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 10 mV p-p.
±12
±15
10
10
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.
Full isolation is provided to help cut ground loops in
industrial systems, where unknown input power quality could
create havoc with sensitive, high precision analog circuitry.
Other input and output voltage combinations may be
factory ordered, contact CALEX applications engineering at
1-800-542-3355 for more information.
No extra components or heatsinking are required for most
applications saving you design time and valuable PCB space.
10 Watt Dual WD Series Block Diagram
A
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
3/2001
1
10 Watt WD Dual “Low Input” Series DC/DC Converters
Input Parameters*
Model
24D5.850WD
24D12.400WD
24D15.320WD
Units
MIN
MAX
9
36
Voltage Range
VDC
Input Current Full Load
TYP
450
10
510
15
510
15
mA
No Load TYP
Efficiency
TYP
79
10
78
78
20
%
Switching Frequency
TYP
100
kHz
Maximum Input
Overvoltage,
100ms Maximum
Turn-on Time,
1% Output Error
MAX
45
VDC
ms
TYP
20
(2)
Recommended Fuse
Output Parameters*
Model
24D5.850WD
24D12.400WD
24D15.320WD
Units
Output Voltage
±5
±12
±15
VDC
MIN
±4.950
±5.000
±5.050
±11.900
±12.000
±12.100
±14.900
±15.000
±15.100
Output Voltage Accuracy TYP
MAX
VDC
mA
%
MIN
Rated Load Range (3)
MAX
0
±850
0
±400
0
±320
Load Regulation (4)
25% Max load to
MAX
TYP
0.1
0.5
0.1
0.5
0.1
0.5
Max Load
Cross Regulation (5)
TYP
2.5
1.2
1.0
%
%
Line Regulation
Vin = 9 - 36 VDC
TYP
MAX
0.1
0.7
0.1
0.3
0.1
0.3
Short Term Stability (6)
Long Term Stability
Noise, Peak - Peak (1)
RMS Noise
TYP
TYP
TYP
TYP
< 0.01
< 0.1
70
%/24Hrs
%/kHrs
100
30
60
15
mV P-P
mV RMS
20
TYP
MAX
50
250
Temperature Coefficient
Short Circuit Protection
ppm/°C
Short Term Current Limit
NOTES
(6) Short term stability is specified after a 30 minute warmup
at full load, constant line and recording the drift over a 24
AllparametersmeasuredatTc=25°C,nominalinputvoltage
and full rated load unless otherwise noted. Refer to the
CALEX Application Notes for the definition of terms,
measurement circuits and other information.
*
hour period.
A
(7) Case is tied to the CMN output pin.
(1) Noise is measured per CALEX application notes. Measurement
bandwidth is 0-20 MHz. RMS noise is measured over a 0.01-1
MHzbandwidth.TosimulatestandardPCBdecouplingpractices,
output noise is measured with a 10µf tantalum and 0.01µF
ceramic capacitor located 1 inch away from the converter.
(8) Thefunctionaltemperaturerangeisintendedtogiveanadditional
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 may reduce the expected operational
life. The data sheet specifications are not guaranteed over
the functional temperature range.
(2) See our application note for picking the correct fuse size.
(3) The converter may be safely operated at any load from zero to
the full rating. Dynamic response of the converter may degrade
if the converter is operated with less than 25% output load.
(9) Thecasethermalimpedanceisspecifiedasthecasetemperature
rise over ambient per package watt dissipated.
(10) See the applications section for more information on applying
the ON/OFF pin.
(4) Load regulation is defined for loading/unloading both outputs
simultaneously. Load range is 25 to 100%.
(11) Specifications subject to change without notice.
(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%.
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
3/2001
2
10 Watt WD Dual “Low Input” Series DC/DC Converters
General Specifications*
All Models
Units
ON/OFF Function
OFF Logic Level
or Tie Pin to -Input (10)
MAX
< 0.4
VDC
Open Circuit Voltage
Input Resistance
TYP
TYP
1.4
2
VDC
kohms
Converter Idle Current
ON/OFF Pin Low
TYP
6
mA
Isolation (7)
Isolation Voltage
Input to Output
10µA Leakage
Input to Output
Capacitance
BOTTOM VIEW
SIDEVIEW
MIN
TYP
700
350
VDC
pF
Mechanical tolerances unless otherwise noted:
X.XX dimensions: ±0.03 inches
Environmental
X.XXX dimensions: ±0.005 inches
MIN
MAX
MIN
MAX
MIN
MAX
TYP
TYP
-40
85
-50
100
-55
105
Case Operating Range
°C
°C
°C
Case Functional Range (8)
Storage Range
Pin
1
Function
+ INPUT
- INPUT
+ OUTPUT
CMN
Thermal Impedance (9)
Unit Weight
16
°C/Watt
2
1.2
oz
3
Mounting Options
4
PCB Mounting Kits
MS6, MS8, MS15
ON/OFF
5
- OUTPUT
ON/OFF
Optional ON/OFF
6
- O Suffix on part Number
Applications Information
You truly get what you pay for in a CALEX converter, a
complete system oriented and specified DC/DC converter -
nosurprises,noexternalnoisecircuitsneeded,noheatsinking
problems, just “plug and play”.
The WD 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.
Figure 1.
Keep reading, you’ll find out why.
If the source impedance driving the WD Converter is more than
about 0.15 ohms at 100 kHz the optional capacitor C1 may be
required (See text for more information). Optional transient protector
diodes may be used if desired for added input and output protection.
The fuse serves as a catastrophic failure protector and should not
be omitted.
General Information
A
The universal 9 to 36 volt input allows you to specify your
system for operation from any 12, 24 or 28 volt nominal input.
Five sided shielding is standard along with specified
operation over the full industrial temperature range of -40 to
+85°C case temperature.
to the battery. If the converter is located more than about 1-2
inches from the input source an added capacitor may be
required. This capacitor should be connected directly at the
input pins for proper operation.
Applying the Input
Figure 1 shows the recommended input connections for the
WD Dual 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.
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
When using the WD Dual be sure that the impedance at
the input to the converter is less than about 0.15 ohms from
DC to 100 kHz, this is usually not a problem in battery
powered systems when the converter is connected directly
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
3/2001
3
10 Watt WD Dual “Low Input” Series DC/DC Converters
the power is reduced. In general you should keep the peak to
peak voltage measured across the input pins less than 0.25
volts (p-p) (not including the high frequency spikes) for
maximum converter performance.
There is no lower limit on the allowed source impedance,
it can be any physically realizable value, even approaching 0.
L1 = 7.5µH
C1 = SEE TEXT
If the source impedance is too large in your system you
should choose an external input capacitor as detailed below.
C2 = 10µF/50V, 0.25 - 1 OHM ESR
Figure 2.
This circuit will reduce the input reflected ripple current to less than
100 mA peak to peak. See the discussion in the text for help on the
optimum selection of C1. L1 should be sized to handle the maximum
inputcurrentatyourlowestoperatingvoltageandmaximumexpected
output power.
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.
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
capacitorsinparalleltoachievethesameripplecurrentrating.
This may save space in some systems.
Several system tradeoffs must be made for each particular
system application to correctly size the input capacitor.
Theprobableresultofundersizingthecapacitorisincreased
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.
United Chemi-Con
Suggested Part:
LXF, SXE, RXC, RZ and RZA series
LXF50VB120M8X20LL
There is no one optimum value for the input capacitor. The
size and capacity depend on the following factors:
120µF, 50V, 105°C RATED
ESR=0.14 OHMS
Allowable Ripple at 85°C = 1.0A
1) Expected ambient temperature and your temperature
derating guidelines.
2) Your ripple current derating guidelines.
Nichicon
Suggested Part:
PR and PF series
UPR1H470MPH
470µF, 50V, 105°C RATED
ESR=0.1 OHMS
Allowable Ripple at 85°C = 1.0A
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.
Panasonic
Suggested Part:
HFG, HFQ, HFZ Series
ECA1HFQ151
150µF, 50V, 105°C RATED
ESR=0.16 OHMS
Allowable Ripple at 85°C = 1.0A
Remote ON/OFF (Optional)
A
Factors3and4realisticallydeterminetheworstcaseripple
current rating required for the capacitor along with the RMS
ripple current curve.
TheWDdualserieshasanoptionalRemoteON/OFFpin. This
option allows a control signal to place the WD Dual in a very
low power state ( <6 mA TYP).
Factor 5 is not easy to quantify. At CALEX we can make no
assumptions about a customers system so we leave to you
the decision of how you define how big is big enough.
Do not drive this input from a logic gate directly. The ON/
OFF pin must be left floating to turn the converter ON and
allow normal operation. This input is noise sensitive and
should not be routed all over your PCB.
Suitable capacitors for use at the input of the converter are
given at the end of this section.
When the ON/OFF pin is pulled low with respect to the -
Input pin 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. Using the ON/OFF pin to
control the WD’s operation prevents the large inrush current
that would be experienced if the +Input pin was opened and
closed.
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 100 mA peak-peak (Vin = 24 V, 20
MHz bw). See the discussion above for the optimum selection
of C1.
The ON/OFF pin should never be pulled more than -0.3
volts below the -Input pin or have a voltage of greater than +3
volts applied to it.
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
3/2001
4
10 Watt WD Dual “Low Input” Series DC/DC Converters
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 uF, 0.5 to 5 Ohm ESR
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.
Applying the Output
Figure 1 shows typical output connections for the WD 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 uF 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,
and by all means use our factory tested low noise circuit
provided.
Also see the CALEX application note “Dealing With
CommonModeNoise”formoreinformationonusingcommon
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 >20 dB of
absorption loss to both electric and magnetic fields at 100
kHz, while at the same time providing 20 to 40 % better heat
sinkingovercompetitivethinsteel,aluminumorplasticdesigns.
Ultra Low Noise Output Circuit
The circuit shown in figure 3 can be used to reduce the output
noise to below 10 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 WD Dual as possible, even if your load is at some
distance from the converter.
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 350 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.
L1 = 20µH
C1 = 22µF/20V, TANTALUM
Figure 3.
C2 = 0.01µF/100V, CERAMIC
Temperature Derating
This circuit can reduce the output noise to below 10 mV p-p over a
20 MHz bandwidth. Size inductor L1 appropriately for the maximum
expected load current. The filter should be constructed as close as
possible to the converter and all of the ground connections must be
as short as possible back to the CMN pin.
TheWDDualseriescanoperateupto85°Ccasetemperature
withoutderating.Casetemperaturemayberoughlycalculated
from ambient by knowing that the case temperature rise is
approximately 16°C per package watt dissipated.
For example: If a WD Dual converter is delivering 8 Watts
with a 24 volt input, at what ambient could it expect to run with
no moving air and no extra heatsinking?
Single Ended Loads
The WD Dual may be operated as a single ended output to get
either 10, 24 or 30 volts output as shown in figure 1. If the
output is operated single ended then the CMN pin should be
left floating.
Efficiency of the converter is approximately 76% at 8 watts
of output power, this leads to an input power of about 10.5
A
Watts. The case temperature rise would be 10.5 - 8 Watts or
2.5 Watts × 16 = 40°C. This number is subtracted from the
maximum case temperature of 85°C to get: 45°C.
Full power is available when operating single ended. For
example: If a 24D5.850WD is operated as a 10 volt output
then a full 0.850 amps is available at 10 volts.
This example calculation is for a WD 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.
Operation With Very Light Loads
Dynamic response and cross regulation of the WD Dual will
degrade when the unit is operated with less than about 25%
of full rated power. If this is a problem the most lightly loaded
output may be “Pre-Loaded” with a resistor to common as
needed.Theexactamountofpreloadingrequiredisdependent
on your system requirements, so some experimentation is
necessary to arrive at the optimum value.
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.
Grounding
Remember, it is the system designers responsibility to be
sure that the case temperature of the WD Dual does not
exceed 85°C for maximum reliability in operation.
The input and output sections are fully floating from each
other. They may be operated fully floating or with a common
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
3/2001
5
10 Watt WD Dual “Low Input” Series DC/DC Converters
Typical Performance (Tc=25°C, Vin=Nom VDC, Rated Load).
INPUT CURRENT Vs. LINE INPUT VOLTAGE
EFFICIENCY Vs. LOAD
2.5
2.0
1.5
1.0
0.5
0.0
85
80
75
70
65
60
55
LINE = 9VDC
100% LOAD
LINE = 24VDC
LINE = 36VDC
50% LOAD
0
5
10
15
20
25
30
35
40
0
10
20
30
40
50
60
70
80
90
100
LINE INPUT (VOLTS)
LOAD (%)
EFFICIENCY Vs. LINE INPUT VOLTAGE
RMS INPUT CURRENT Vs. LINE INPUT VOLTAGE
90
85
80
75
70
65
60
1.0
0.8
0.6
0.4
0.2
0.0
50% FULL LOAD
100% FULL LOAD
100% LOAD
75% LOAD
50% LOAD
8
12
16
20
24
28
32
36
8
12
16
20
24
28
32
36
LINE INPUT(VOLTS)
LINE INPUT (VOLTS)
A
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
3/2001
6
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