45 Watt XT Single Series DC/DC Converters
Features
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!
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!
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Fully Shielded/Filtered Design
Lowest Noise Outputs, 50 mV P-P
Very Low and Specified Reflected Ripple Current
Low I/O Capacitance, 500 pF Typical
Water Washable Shielded Copper Case
Five Year Warranty
Description
These single output converters are designed for ultra wide
input range low noise telecommunications, industrial, and
instrument applications. The very wide input range (4:1) is
ideal for battery or unregulated input applications while the
low noise complements even the most sensitive analog
circuitry.
These converters are state of the art 220 kHz MOSFET
based designs that provide outstanding line and load regulation
and efficiencies exceeding 80%.
Remote output voltage sense, output voltage trim and ON/
OFF functions are also included.
The converters are protected from output shorts to common
by a high speed pulse by pulse digital current limit circuit and
a self resetting thermal overload protection circuit.
As with all CALEX converters the 45 watt XT Single series
is covered by our 5 Year Warranty.
Model
24S3.6XT
24S5.7XT
24S12.4XT
24S15.3XT
48S3.7XT
48S5.8XT
48S12.4XT
48S15.3XT
Selection Chart
Input Range
VDC
Min
Max
9
9
9
9
20
20
20
20
36
36
36
36
72
72
72
72
Output
VDC
3.33
5.0
12.0
15.0
3.33
5.0
12.0
15.0
Output
AMPS
6.0
7.0
3.75
3.0
7.0
8.0
3.75
3.0
Note: See Input Derating Curves for 24S Models.
45 Watt XT Single 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
1
3/2001
45 Watt XT Single Series DC/DC Converters
Input Parameters*
Model
Voltage Range (8)
Input Current Full Load
No Load
Efficiency
Reflected Ripple (1)
Switching Frequency
Maximum Input Overvoltage, 100ms
Turn-on Time, 1% Output Error
Recommended Fuse
Model
Voltage Range
Input Current Full Load
No Load
Efficiency
Reflected Ripple (1)
Switching Frequency
Maximum Input Overvoltage, 100ms
Turn-on Time, 1% Output Error
Recommended Fuse
MIN
MAX
TYP
TYP
TYP
TYP
TYP
TYP
MAX
TYP
48S3.7XT
48S5.8XT
20
72
640
10
76
1050
10
79
45
5
220
80
25
(2)
1150
10
81
1150
10
81
MIN
MAX
TYP
TYP
TYP
TYP
TYP
TYP
MAX
TYP
24S3.6XT
24S5.7XT
9
36
1120
10
74
1900
10
76
60
8
220
45
25
(2)
48S12.4XT
48S15.3XT
2400
10
79
2400
10
79
24S12.4XT
24S15.3XT
Units
VDC
mA
%
mA p-p
mA RMS
kHz
VDC
ms
AMPS
Units
VDC
mA
%
mA p-p
mA RMS
kHz
VDC
ms
AMPS
Output Parameters*
Model
Output Voltage
Output Voltage Accuracy
Rated Load Range (9)
Load Regulation: 25%-100%
Full Load
Line Regulation
Vin = Min-Max VDC
Transient Response (3)
Dynamic Response (4)
Input Ripple Rejection (5)
Noise, 0-20MHz bw (1)
RMS Noise, 0.1 - 1MHz bw (1)
Temperature Coefficient
Short Circuit Protection
MIN
TYP
MAX
MIN
MAX
TYP
MAX
TYP
MAX
TYP
TYP
TYP
TYP
TYP
TYP
MAX
25
6
25
10
25
6
50
10
24S3.6XT
48S3.7XT
24S5.7XT
48S5.8XT
24S12.4XT
48S12.4XT
24S15.3XT
48S15.3XT
UNITS
VDC
VDC
A
%
0.1
0.2
100
120
> 25
25
6
50
10
%
100
µs
mV peak
dB
25
6
50
10
mV p-p
mV RMS
ppm/°C
3.33
3.30
3.33
3.36
1.5
6
1.5
7
1.7
7
5
4.95
5.00
5.05
0.3
8
0.01
0.1
0.5
2.0
500
200
12
11.90
12.00
12.10
0.3
3.75
15
14.90
15.00
15.10
0.3
3
100
250
A
120
50
150
Output to Common and Thermal Protection
NOTES
*
(1)
(2)
(3)
(4)
All parameters measured at Tc = 25°C, 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.
Noise is measured per CALEX application notes. Measurement
bandwidth is 0-20 MHz. RMS noise is measured over a 0.01-1
MHz bandwidth. To simulate standard PCB decoupling practices,
output noise is measured with a 10µf tantalum and 0.01µF
ceramic capacitor located 1 inch away from the converter. Input
ripple is measured into a 10µH source impedance.
See our application note for picking the correct fuse size.
Transient response is specified for a 50 to 75% step load
change. Rise time of step is 2 microseconds.
Dynamic response is the peak overshoot for a transient as
described in note 3.
Input ripple rejection is specified for a DC to 120 Hz ripple with
a modulation amplitude of 1% of Vin or less.
(6) 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 may reduce the expected operational
life. The data sheet specifications are not guaranteed over
the functional temperature range.
(7) The case thermal impedance is specified as the case temperature
rise over ambient per package watt dissipated.
(8) See power/voltage derating curves.
(9) No harm when operated at less than maximum load. See section
on Operation with Light Loads.
(10) Specifications subject to change without notice.
(5)
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
3/2001
45 Watt XT Single Series DC/DC Converters
General Specifications*
All Models
ON/OFF Function
ON Logic Level
or Leave Pin Open
OFF Logic Level
or Tie Pin to -Input
Open Circuit Voltage
Input Resistance
Converter Idle Current
ON/OFF Pin Low
Isolation
Isolation Voltage
Input to Output, 24S
Input to Output, 48V
10µA Leakage
Input to Output
Capacitance
Output Trim Function
Trim Range
Input Resistance
Open Circuit Voltage
Environmental
Case Operating Range
Case Functional Range (6)
Storage Range
Thermal Shutdown
Case Temperature
Thermal Impedance (7)
Unit Weight
Mounting Options
MS9
-I Suffix on Part Number
-HS Suffix on Part Number
Chassis Mounting Kit
Inserts In Case
Heat Sink Option
MIN
MAX
MIN
MAX
MIN
MAX
TYP
TYP
TYP
-40
85
-55
90
-55
100
100
4.4
7
°C
°C
°C
°C
°C/Watt
oz
Pin
1
2
3
4
5
6
7
8
Function
+INPUT
-INPUT
+SENSE
TRIM
-SENSE
+OUTPUT
CMN
ON/OFF
Units
MIN
MAX
TYP
TYP
TYP
4
1.5
5
6
7
VDC
VDC
VDC
kohms
mA
MIN
MIN
TYP
700
1544
500
VDC
pF
BOTTOM VIEW
SIDE VIEW
Mechanical tolerances unless otherwise noted:
MIN
MIN
TYP
±10
10
2.5
%
kohms
VDC
X.XX dimensions: ±0.020 inches
X.XXX dimensions: ±0.005 inches
Application 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 filtering circuits needed, no
heatsinking problems, just “plug and play”.
The 45 watt XT Single 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.
Keep reading, you’ll find out why.
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 XT converters achieve 50 mV peak to peak
typical and are fully specified and tested to a wide bandwidth
of 0-20 MHz.
A
Input filtering reduces reflected ripple noise and is similarly
low and also fully specified for typical values (exact value
depends on input voltage range). Typical RMS noise over a 10
kHz to 1 MHz bandwidth is specified for both the input and
output.
Full overload protection is provided by independent pulse-
by-pulse current limiting and an over-temperature shutdown
circuit. These protection features assure you that our XT
single will provide you with zero failure rate operation.
Five sided shielding is standard along with specified operation
over the full industrial temperature range of -40 to +85°C case
temperature.
General Information
The XT Single series is 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 10 mA
from the input source.
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
3/2001
45 Watt XT Single Series DC/DC Converters
Applying the Input
Figure 1 shows the recommended input connections for the
XT 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 2.
The simplified schematic of the XT Single series ON/OFF pin. The
input impedance is approximately 6k ohms. By leaving this pin
floating the converter will be in the ON state. When the pin is pulled
below 1.4 volts (with respect to the -Input pin) the converter is placed
in the power down or OFF state. See our application note on the
remote ON/OFF function for more information.
Applying The Output
Figure 1.
Standard connections for the XT single input. The ON/OFF pin may
be left floating if it is not used. The input protection fuse should not
be omitted. If desired, an external transient protection diode (D1)
can be used at the input. See “Applying the input” for suggestions
regarding C1.
Figure 3 shows typical output connections for the XT single.
In most applications no external output capacitance will be
necessarily. Only your normal 1 to 10 µF and 0.001 to 0.1 µF
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.
No external capacitance on the input is required for normal
operation, in fact it can degrade the converters performance.
Extremely low ESR capacitors (< 0.5 ohms) should not be
used at the input as this will cause peaking of the input filters
transfer function and actually degrade the filters performance.
Normal RF bypass capacitors in the 1000 pF to 0.01 µF range
may be used without harm.
Remote ON/OFF Pin Operation
The remote ON/OFF pin may be left floating if this function is
not used. The equivalent input circuit for the ON/OFF pin is
shown in figure 2. The best way to drive this pin is with an open
collector/drain or relay contact. See our application note titled
“Understanding the remote ON/OFF function” for more
information about using the remote ON/OFF pin.
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 capacitor fully charged, this prevents the large inrush
current spike that occurs when the +input pin is opened and
closed.
A
Figure 3.
The remote sense lines should be connected to their respective
output pins even if they are not used in your application. If desired,
an external transient protection diode can be used. D2 and D3 are
optional, for more information see the “Remote sense” section.
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
3/2001
45 Watt XT Single Series DC/DC Converters
Remote Sense
The XT single features provisions for remote sense
connections. These allow the power supply to correct for line
drops of up to 0.6 volts per side. The remote sense connections
should be made with twisted pair wire or closely coupled PCB
traces. If the remote sense is not to be used these pins must
be connected to their respective output pins for proper output
voltage accuracy and regulation. There is approximately 2 mA
of current flowing in the remote sense lines.
Care should be taken to not disconnect the output pins
before the remote sense pins while the converter is in operation.
If this happens the output load current will run down the sense
leads possibly causing an output overvoltage condition. If the
unit must be “Hot Plugged” in the intended application, provision
should be made to disconnect the sense leads before the
power leads, disconnect the input power first or use the
remote ON/OFF to stop the converters operation.
Another option is to attach two 1N4001 diodes from pins 6
to 3 and pins 7 to 5 as shown in figure 3. These diodes will
shunt any current through the 10 ohm internal resistors
connected between the outputs and their respective outputs
when the voltage drop across the resistors exceeds
approximately 0.6 volts. This will limit momentary overvoltages
to about 1.2 volts during a hot plug-in.
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 or to adjust the +5
output up to 5.2 volts for ECL applications. Figure 4 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.
Non Standard Output Voltages
The 12 and 15 volt XT’s will typically trim much lower than the
-10% specified. This allows the 12 and 15 volt XT’s to be
trimmed lower than specified for RF or other special
applications.
The 12 volt XT’s can be typically trimmed over a range of
8.6 to 13.3 volts. The 15 volt XT’s can be typically trimmed
over a range of 9.8 to 16.8 volts.
Down trim actually can reduce the minimum input voltage
in some circuits. Full up trim may not be achievable at
minimum input voltage and full rated load.
The maximum current available does not increase from the
listed maximum under low trim conditions.
Ultra Low Noise Output Circuit
The circuit shown in figure 5 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. The remote sense lines should be looped back
directly to the output pins to prevent feedback loop oscillation
due to the filters extra phase shift.
C1, C3 - 220µF, 25V UNITED CHEM-CON LXF SERIES
C2 - 0.01µF, 100V CERAMIC
L1 - 5µH POWER INDUCTOR
Figure 5.
For very low noise applications this circuit will reduce the output
noise to less than 10 mV P-P over a 0-20 MHz bandwidth. Be sure
to size the inductor appropriately for the maximum expected load
current.
A
Operation With Light Loads
At output loads less than specified minimum, the XT single will
operate in a “Burst Mode”. That is the XT will cease PWM
operation and instead operate in more of a burst mode. This
mode significantly reduces the light load input current to the
XT single. Under these conditions the output of the XT will
contain a larger than normal (compared to full load) output
noise, but at a lower frequency.
If this is a problem in your application the XT single may be
used with a dummy load resistor to keep the static output
current above the specified mimimum load.
Figure 4.
The output can be trimmed by either a trimpot or fixed resistors. If
fixed resistors are used their values may range from 0 to infinite
ohms. The trimpot should be 10k ohms for 3.3 and 5 volt outputs or
20k ohms for 12 and 15 volt outputs.
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
3/2001
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