A
15 Watt TC Single 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
1eco# 041007-1
+ INPUT 3
2
1
-INPUT
ON/OFF
4
5
6
+ OUTPUT
CMN
TRIM
SHIELDED
ISOLATION TRANSFORMER
LOW TC
BANDGAP REFERENCE
ISOLATED
FEEDBACK
CURRENT
MODE
PWM
FIVE-SIDED SHIELDED COPPER CASE
Features
-40° to +90°C Case Operating
Range Standard
Dual Stage Output Filter for Low Noise Operation
Very Low OFF Current, 1 mA Typically
Water Washable Design
Five Year Warranty
Description
These single output DC/DC converters are designed to provide
a wide range of PCB mount power solutions. The extra wide
3:1 input voltage range covers the common American and
European telecom standards along with 24 volt industrial
control applications.
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 TC Single Series continues the CALEX tradition of
reliable design by including transient overvoltage suppressor
diode protection at the input and output terminals. Also
provided as standard are overcurrent protection circuits.
These features assure zero failure rate operation when using
the TC Single Series.
15 Watt TC Single Series Block Diagram
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A
15 Watt TC Single 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
2eco# 041007-1
NOTES
*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.
(1) See our application note for picking the correct fuse size.
(2) 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 0.1µF, ceramic capacitor
located 1 inch away from the converter.
(3) Minimum load required for rated regulation only. Dynamic
response may degrade if run at less than 25% full load.
(4) Short term stability is specified after a 30 minute warm-up at full
load, and with constant line, load and ambient conditions.
(5) The transient response is specified as the time required to settle
from a 50 to 75% step load change (rise time of step = 2µSec)
to a 1% error band.
(6) Dynamic response is the peak overshoot voltage during the
transient response time defined in note 5.
(7) The input ripple rejection is specified for DC to 120Hz ripple with
a modulation amplitude of 1% Vin.
(8) 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 +75VDC.
(9) Case is tied to Pin 3, +Input.
(10) The case thermal impedance is specified as the case temperature
rise over ambient per package watt dissipated.
(11) Specifications subject to change without notice.
(12) 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.
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A
15 Watt TC Single 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
3eco# 041007-1
SIZE TRACES FOR 1 AMP DC MAXIMUM
FUSE
C1
TO INPUT
SOURCE LOAD
SIZE TRACES
APPROPRIATELY FOR
LOAD REQUIREMENTS
*
PINS 1 AND 6 MAY BE LEFT
FLOATING IF NOT USED
**
3
2
16
5
4
+ INPUT
- INPUT
ON/OFF
+ OUTPUT
CMN
TRIM
niPnoitcnuF
1FFO/NO
2TUPNI-
3TUPNI+
4TUPTUO+
5NMC
6MIRT
FIGURE 1.
Recommended application circuit for TC Single Series
Mechanical tolerances unless otherwise noted:
X.XX dimensions: ±0.020 inches
X.XXX dimensions: ±0.005 inches
Seal around terminals is not hermetic. Do not immerse units in any
liquid.
15 Watt TC Single Typical Application
Figure 1 shows the recommended connections for the 15 Watt
TC 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 serves two purposes:
1) It prevents unlimited current from flowing in the case of a
catastrophic system failure
2) UL regulations for telecom equipment require the use of a
fuse. See CALEX Application Notes for more info on sizing
the input fuse.
BOTTOM VIEW SIDE VIEW
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A
15 Watt TC Single 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
4eco# 041007-1
Solution
According to the 15 Watt TC Single Series “Reflected Input
Ripple vs. Line Input” curve at 40 VDC input and 2.25 Amps
output (75% of rated load), the reflected input ripple can be
read as 650 mA RMS. From the derating guidelines the
capacitor’s rated voltage and ripple current can be determined.
Capacitor voltage rating is calculated as:
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 15 Watt TC Single Series
operates at 120 kHz the frequency usually does not have to
be derated since most modern low ESR capacitors are rated
at 100 kHz.
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.
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=1.45 A @ 105°C
Nichicon PR and PF
Suggested Part: UPR2A102MPH
1000µF, 100V, 105°C Rated
ESR=0.047 ohms
Allowable Ripple=1.32 A @ 105°C
Sizing The Input Capacitor
For maximum reliability the TC 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 load expected 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 20
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.
Example Of Capacitor Sizing
Given the following conditions, select the minimum size
capacitor needed to provide reliable performance:
Converter ......................................... 48S5.3000TC
Minimum Input Voltage .................... 40 VDC
Maximum Input Voltage ................... 52 VDC
Maximum Load ................................ 2.25 Amps
Maximum Ambient Temperature ..... 40°C
Your Capacitor Voltage
Derating Guideline ........................... 70% of Maximum
Specification
Your Capacitor Current
Derating Guideline ........................... 70% of Maximum
Specification
V = 1 x
Maximum Expected Input
Voltage Derating Factor
V = 1 x 52 = 74
Volts or greater
0.7
I = 1 x
Reflected Ripple
Current Derating Factor
= 1 x 650
mA
= 0.93
A RMS or greater at 45°C
0.7
(40°C ambient + 5°C for self heating)
A
15 Watt TC Single 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
5eco# 041007-1
USING TRIMPOT
USING FIXED RESISTORS
4
6
5
4
6
5
10 K LOAD
LOAD
TRIM
DOWN
TRIM
UP
+ OUT
TRIM
CMN
+ OUT
TRIM
CMN
Panasonic HFE Series
Suggested Part: ECEA2AFE221L
220µF, 100V, 105°C Rated
ESR=0.089 ohms
Allowable Ripple=1.04 A @ 105°C
The suggested capacitors will work for any line and load
condition, however, they may be oversized for your application.
Low Noise Input Filtering Circuit
To reduce the input reflected ripple to less than 50 mA peak
to peak the circuit shown in Figure 2 may be used. Toroid core
inductors have theoretically lower radiated noise than a rod
core. 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.
FIGURE 2. Low noise input filter circuit
Remote ON/OFF Circuit Operation
The remote ON/OFF pin is best applied as follows:
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”.
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
3 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.”
THIS CAPACITOR IS REQUIRED
FOR PROPER OPERATION
FUSE 50 µH, 1000 mA
TO INPUT
SOURCE
10 µF
100 V
3
2
+ INPUT
- INPUT
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.
Temperature Derating Guidelines
Care must be taken in the application of all power devices. Be
sure to account for the self heating in your instrument due to
the power converter and the loads. For minimum temperature
gradient, the hottest components should be mounted at the
bottom of your system (bottom of a vertical PCB) and the
coolest components at the top of the system. This will help to
even the temperature of the entire system and prevent
temperature gradients.
The 15 Watt TC Single Series has a thermal impedance of
10°C per package watt dissipated. During normal operation
the 15 Watt TC Single Series can be expected to run at 80%
efficiency at 48 VDC and full load. This means that the 15 Watt
TC Single Series is dissipating nearly 4 Watts internally at full
load. This, therefore, translates to a package temperature rise
of about 40°C (10°C/watt x 4 watts dissipated).
The maximum rated case temperature for the 15 Watt TC
Series is 90°C. This means that, in the absence of other heat
sources (including the load that the converter is powering)
and with at least 3 inches of clearance, the 15 Watt TC Single
Series can be expected to operate at an ambient of 50°C.
Additional heat sinks or cooling air flow can extend the
ambient temperature of operation significantly.
Figure 3. Output trim methods
A
15 Watt TC Single 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
6eco# 041007-1
20 25 30 35 40 45 50 55 60
LINE INPUT(VOLTS)
75
77
80
82
85
EFFICIENCY(%)
EFFICIENCY Vs. LINE INPUT VOLTAGE
100% FULL LOAD
50% FULL LOAD
0 102030405060708090100
LOAD (%)
60
65
70
75
80
85
90
EFFICIENCY (%)
EFFICIENCY Vs. LOAD
LINE = 20VDC
LINE = 48VDC
LINE = 60VDC
20 25 30 35 40 45 50 55 60
LINE INPUT (VOLTS)
0.20
0.40
0.60
0.80
1.00
REFLECTED RMS RIPPLE (AMPS)
INPUT RIPPLE Vs. LINE INPUT
100%
FULL LOAD
75%
FULL LOAD
50%
FULL LOAD
0 102030405060
LINE INPUT (VOLTS)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
INPUT CURRENT (AMPS)
INPUT CURRENT Vs. LINE INPUT VOLTAGE
100% LOAD
50% LOAD
0 20 40 60 80 100 120 140 160 180
OUTPUT LOAD (%)
0
20
40
60
80
100
120
OUTPUT VOLTAGE (%)
OUTPUT VOLTAGE Vs. OUTPUT LOAD
10 100 1000 10000 100000 1000000
FREQUENCY (Hz)
.01
.1
1
OUTPUT IMPEDANCE (OHMS)
OUTPUT IMPEDANCE Vs. FREQUENCY
48S5.3000TC
48S15.1000TC
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90
CASE TEMPERATURE (Deg C)
-0.5
-0.4
-0.3
-0.2
-0.1
-0.0
0.1
0.2
NORMALIZED OUTPUT (%)
OUTPUT VOLTAGE Vs CASE TEMPERATURE
Typical Performance (Tc=25°C, Vin=Nom VDC, Rated Load, 48S12.1250TC)