30 Watt NT Single Series DC/DC Converters
Features
Only 2.02" x 1.62" x 0.55" high
-40° to +90°C case operating range standard
Very low OFF current, 1 mA typically
Transient overvoltage protected output
Overcurrent and overtemperature protection
Up to 86% efficiency
5 Year Warranty
Selection Chart
Description
These single output DC/DC converters are designed to provide
a wide range of PCB mount power solutions. The wide 2:1
input voltage range covers the common American and
European telecom standards.
For flexibility, a trim pin is included to adjust the output
voltage. Use it to compensate for voltage drops in your
system’s wiring or to achieve non standard voltages. Use the
remote ON/OFF function to maximize battery life.
The NT Single Series continues the CALEX tradition of
reliable design by including transient overvoltage suppressor
diode protection at the output terminals. Also provided as
standard are overcurrent and overtemperature protection
circuits. These features assure zero failure rate operation
when using the NT Single Series. All CALEX products are
backed by a 5 Year Warranty.
Model
*48S5.5000NT
48S12.2500NT
48S15.2000NT
Input Range
VDC
Min
Max
36.0
36.0
36.0
72.0
72.0
72.0
Output
VDC
5.0
12.0
15.0
Output
mA
5000
2500
2000
*Agency Approvals: CSA/UL 60950
25 - 30 Watt NT Single Series Block Diagram
SHIELDED
ISOLATION TRANSFORMER
THERMAL SHUTDOWN
A
C
D
4 + OUTPUT
+ INPUT 3
- INPUT 2
CURRENT
MODE
PWM
5 CMN
6 TRIM
ISOLATED
FEEDBACK
ON/OFF 1
Output
C
D
5
12
15
270µF
40µF
40µF
6.8V
15V
18V
FIVE-SIDED SHIELDED COPPER CASE
LOW TC
BANDGAP REFERENCE
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# 041007-1
30 Watt NT Single Series DC/DC Converters
Input Parameters*
Model
Voltage Range
Input Current Full Load
No Load
Efficiency
Switching Frequency
Maximum Input Overvoltage,
100ms No Damage
Turn-on Time
Recommended Fuse
MIN
TYP
MAX
TYP
TYP
TYP
TYP
MAX
TYP
48S5.5000NT
48S12.2500NT
36.0
48.0
72.0
730
4
86
200
85
10
(2)
48S15.2000NT
Units
VDC
730
4
86
mA
%
kHz
VDC
ms
630
4
84
Output Parameters*
Model
Output Voltage
Rated Load (3)
Voltage Range
100% Load
Load Regulation
Min-Max Full Load
Line Regulation
Vin = Min-Max VDC
Short Term Stability (4)
Long Term Stability
Transient Response (5)
Dynamic Response (6)
Input Ripple Rejection (7)
Noise, 0-20MHz bw (8)
Temperature Coefficient
Overvoltage Clamp
Short Circuit Protection to
Common for all Outputs
MIN
MAX
MIN
TYP
MAX
TYP
MAX
TYP
MAX
TYP
TYP
TYP
TYP
TYP
TYP
TYP
MAX
TYP
48S5.5000NT
5
1250
5000
4.950
5.000
5.050
0.5
1.0
48S12.2500NT
12
625
2500
11.900
12.000
12.100
0.2
1.0
0.2
1.0
<0.02
<0.05
200
300
60
48S15.2000NT
15
500
2000
14.900
15.000
15.100
0.2
1.0
Units
VDC
mA
VDC
%
%
%
200
300
%/kHrs
µs
mV peak
dB
mV P-P
ppm/°C
VDC
125
80
6.8
1% of output voltage
50
150
15
18
Provides continuous protection with current limiting and
thermal overload techniques
NOTES
*
(2)
(3)
(4)
(5)
(6)
All parameters measured at Tc=25 °C case temperature,
nominal input voltage and full rated load unless otherwise
noted. Refer to the CALEX Application Notes for definition
of terms, measurement circuits and other information.
See our application note on fusing DC/DC converters.
Minimum load required for rated regulation only. Module will not
be damaged if run at less than minimum load.
Short term stability is specified after a 30 minute warm-up at
full load, and with constant line, load and ambient conditions.
The transient response is specified as the time required to settle
from 50 to 75% step load change (rise time of step = 20µSec.)
to a 1% error band.
Dynamic response is the peak overshoot voltage during the
transient response time defined in note 5.
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
The input ripple rejection is specified for DC to 120Hz ripple with
a modulation amplitude of 1% Vin.
Noise is measured per CALEX Application Notes. Output
noise is measured with a 0.01µF ceramic connected directly
across the output pins.
The ON/OFF pin is Open Collector TTL, CMOS, and relay
compatible. The input to this pin is referenced to Pin 2, -Input
and is protected to +100 VDC.
Case is tied to Pin 3, +Input.
Full output trim range may not be available at full load and
minimum input voltage. Full trim is guaranteed from minimum
input voltage +5% and full load.
The case thermal impedance is specified as the case
temperature rise over ambient per package watt dissipated.
Specifications subject to change without notice.
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.
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
2
eco# 041007-1
30 Watt NT Single Series DC/DC Converters
General Specifications*
All Models
ON/OFF Function (9)
ON Logic Level
or Leave Pin Open
OFF Logic Level
Input Resistance
Converter Idle Current
ON/OFF Pin Low
Isolation
Isolation Voltage (10)
10µA Leakage
Input-Output
Input to Output
Capacitance
Output Trim Function
Input Resistance
Programming Range (11)
Environmental
Case Operating Range
No Derating
Storage Range
Thermal Impedance (12)
Thermal Shutdown
Case Temperature
General
Unit Weight
Chassis Mounting Kit
Units
MIN
MAX
TYP
TYP
8.0
2.0
100
<1
VDC
VDC
kohms
mA
MIN
TYP
1544
300
VDC
pF
BOTTOM VIEW
Mechanical tolerances unless otherwise noted:
X.XX dimensions: ±0.020 inches
X.XXX dimensions: ±0.005 inches
SIDE VIEW
TYP
MIN
MIN
MAX
MIN
MAX
TYP
TYP
20
±5
-40
+90
-55
100
10
100
kohms
%
Seal around terminals is not hermetic. Do not immerse units in any
liquid.
Pin
1
2
3
4
5
6
Function
ON/OFF
-INPUT
+INPUT
+OUTPUT
CMN
TRIM
°C
°C
°C/Watt
°C
TYP
1.9
MS8
oz
25-30 Watt NT Single Typical Application
Figure 1 shows the recommended connections for the NT
Singles. Capacitor C1 is required for proper operation (see
below). The trim and ON/OFF pins can be safely left floating
if they are not used. The input fuse should not be omitted.
The fuse prevents unlimited current from flowing in the
case of a catastrophic system failure, and also protects the
DC/DC converter input circuit.
SIZE TRACES FOR 1 AMP DC
MAXIMUM
FUSE
TO INPUT
SOURCE
3 + INPUT
C1
D1
2 - INPUT
CMN 5
+ OUTPUT 4
SIZE TRACES
APPROPRIATELY FOR
LOAD REQUIREMENTS
A
LOAD
*
1 ON/OFF
TRIM 6
*
C1 - Is required for proper operation, see text
D1 - Overvoltage clamp is optional, see text
*
PINS 1 AND 6 MAY BE LEFT FLOATING
IF NOT USED
Figure 1.
Recommended application circuit for NT Single Series
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
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eco# 041007-1
30 Watt NT Single Series DC/DC Converters
Sizing The Input Capacitor
For maximum reliability the NT Single Series must use a
capacitor of sufficient ripple handling capability connected
across the input pins. The probable result of undersizing (over
stressing) this capacitor is increased self heating, shortening
of the capacitors and hence shortening of your systems’ life.
Oversizing the capacitor can have a negative effect on your
product’s cost and size, although this kind of overdesign does
not result in shorter life of any components. There is no one
optimum value for this capacitor. The size and capacity are
dependent 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 minimum input voltage expected on the converter
5) The statistical probability that your system will spend a
significant amount of time at any worst case extreme
Factors 1 and 2 are determined by your system design
guidelines. These can range from 50% to 100% of the
manufacturer’s rated maximum, although a usual derating
factor is 70% of manufacturer’s maximum limit. 70% derating
means that if the capacitor manufacturer says their capacitor
can do 1 A RMS and 100 VDC you would not use the part over
700 mA RMS and 70 VDC. Surge voltage rating should also
be evaluated against any expected voltage surges when
selecting a capacitor working voltage.
Factors 3 and 4 realistically determine the worst case ripple
current. The reflected ripple current increases with output
load and increases as the input voltage decreases. So if you
are running with a solid 48 VDC input and at 50% load your
capacitors required ripple current rating would decrease by
more than 2:1 from what would be required for operation at 36
VDC with full load (see the “Input Reflected Ripple” curve).
Factor 5 is not easy to quantify. At CALEX, we can make
no assumptions about a customer’s system so we design for
continuous operation at worst case extremes.
Solution
According to the NT Single Series “Reflected Input Ripple Vs.
Line Input” curve at 40 VDC input and 5 Amps output (100%
of rated load), the reflected input ripple can be read as 975 mA
RMS. From the derating guidelines the capacitor’s rated
voltage and ripple current can be determined.
Capacitor voltage rating is calculated as:
V=
1
Voltage Derating Factor
x
Maximum Expected Input
V=
1
x 52 = 74
Volts or greater
0.7
1
I =
Current Derating Factor
x
Reflected Ripple
1
= 0.7 x 975mA = 1.39
A RMS or greater at
45°C
(40° C ambient + 5° C for self heating)
A capacitor selection can now be made. Look only at
controlled low ESR types (where the ESR is specified as a
maximum) because these usually have the highest ripple
current capability per unit volume.
Be careful to compare apples to apples. Some
manufacturers specify their capacitors at 85°C and others
specify at 105°C. The manufacturers give temperature derating
guidelines so all capacitors should be normalized to your
maximum ambient (plus 5°C to account for self heating)
before making a selection. Since the NT Single Series operates
at 200 kHz the frequency usually does not have to be derated
since most modern low ESR capacitors are rated at 100 kHz
or more.
One note: The temperature derating multipliers are based
on the capacitor’s expected life at 105°C. The life of a
capacitor operating at a significantly lower temperature will
not be greater if the ripple current in the part is increased over
the 105°C rating. This means that a capacitor rated for 1 A
RMS current at 105°C and 2 A RMS at 50°C will have the same
life if used at either point while the same capacitor used at 1
A RMS and 50°C will have a longer life.
Example Of Capacitor Sizing
Given the following conditions, select the minimum size
capacitor needed to provide reliable performance:
Converter ........................................ 48S5.5000NT
Minimum Input Voltage ................... Voltage 40 VDC
Maximum Input Voltage .................. Voltage 52 VDC
Maximum Load ............................... 5 Amps
Maximum Ambient Temperature .... 40°C
Your Capacitor Voltage
Derating Guideline ............... 70% of Maximum
Specification
Your Capacitor Current
Derating Guideline ............... 70% of Maximum
Specification
A
Suggested Capacitor Sources
Suitable capacitors can be acquired from the following sources:
United Chemi-Con
SXE, RXC, RZ and RZA Series
Suggested Part:
SXE100VB221M12.5X35LL
220µF, 100V, 105°C Rated
ESR=0.087 Ohms
Allowable Ripple=1.04 A @ 105°C
Nichicon
Suggested Part:
PR and PF
UPR100102MPHRH
1000µF, 100V, 105°C Rated
ESR=0.047 Ohms
Allowable Ripple=1.32 A @ 105°C
HFE Series
ECEA2AFE221L
220µF, 100V, 105°C Rated
ESR=0.089 Ohms
Allowable Ripple=1.04 A @ 105°C
Panasonic
Suggested Part:
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eco# 041007-1
30 Watt NT Single Series DC/DC Converters
The suggested capacitors will work for any line and load
condition, however, they may be oversized for your application.
High ripple current film capacitors may also be used and may
provide longer life or smaller size.
Low Noise Output Filtering Circuit
Extra output filtering is easy with the NT Series due to the high,
constant 200 kHz switching frequency. The optional circuit
shown in figure 3 can reduce the output noise to 15 mV p-p on
a 5 Volt output converter and 40 mV p-p on 12 and 15 Volt
output converters. The inductor should be sized appropriately
for your maximum load current. No extra large capacitance is
required on the output of the converter other than the
components shown and the standard bypassing on your PCB.
Large, low ESR capacitors on the output of the converter can
actually make the output noise worse or cause oscillation.
See the CALEX application note on “Understanding Output
Impedance” for more information.
Low Noise Input Filtering Circuit
To reduce the input reflected ripple to less than 100 mA peak-
to-peak the circuit shown in Figure 2 may be used. Use
reasonable caution when selecting an inductor other than the
one specified. Nearly any 105°C rated capacitor can be used
for the 10µF / 100V part. To prevent input filter peaking the
ESR should be in the range of 0.5 to 2 ohms. Do not use the
lowest ESR capacitor available for this part. This will render
the filter ineffective.
THIS CAPACITOR IS REQUIRED
FOR PROPER OPERATION
Remote ON/OFF Circuit Operation
The remote ON/OFF pin is best applied as follows:
3 + INPUT
FUSE
20 µH, 1000 mA
To turn the unit off, the ON/OFF pin should be tied to the -
Input pin. This is best done by an open collector arrangement
or contact closure.
To turn the unit on, let the ON/OFF pin float.
If the remote ON/OFF pin is not used, it may be safely left
floating. There is a 100K internal pull-up resistor inside the
unit to +9 Volts DC.
Other applications of the ON/OFF function can be found in
the application note, “Understanding the Remote ON/OFF
Function”.
TO INPUT
SOURCE
10 µF
100 V
2 - INPUT
Figure 2.
Low noise input filter circuit
Input Overvoltage Protection
As shown in figure 1, optional transient overvoltage protection
may be used at the input of the converter. This should be
considered if your application circuit could present a voltage
greater than the NT Series maximum transient voltage listed
on the data sheet. This device could also serve as a reverse
input voltage protector if used with a suitable fuse.
Proper Application Of The Trim Pin
The trim pin is used to adjust the output voltage slightly to
compensate for voltage drops in the system’s wiring. Figure
4 shows the proper application of the trim pin. Either a 10K
trimpot or fixed resistors may be used.
Other applications for the TRIM function can be found in the
CALEX application note, “Applying the Remote Sense and
Trim Functions on DC/DC Converters.”
Use one resistor for either trim up or trim down. The values
can range from infinity to zero ohms with zero ohms providing
the most trim.
A
+ OUTPUT
4
L1
+ OUT 4
+ OUT 4
10K LOAD
TRIM 6
CMN 5
C1
C2
C3
TRIM 6
CMN 5
TRIM
DOWN
LOAD
TRIM
UP
CMN
5
L1 = 5µH
C1, C3 = 0.01µF, CERAMIC
C2 = 10µF/35V, TANTALUM
USING TRIMPOT
USING FIXED RESISTORS
Figure 3.
Low noise output filter circuit
Figure 4.
Output trim methods
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
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eco# 041007-1
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