360
WATT
MTW
SERIES
DC/DC CONVERTERS
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
ECO 161004-1, 170213-2, 170227-1, 170321-1, 170412-2, 170802-
1
Page 1 of
16
Description
The 4:1 Input Voltage 360 Watt Single MTW DC/DC
converter provides a precisely regulated dc output.
The output voltage is fully isolated from the input,
allowing the output to be positive or negative polarity
and with various ground connections. The 360 Watt
MTW meets the most rigorous performance standards
in an industry standard footprint for mobile (12V
IN
),
process control (24V
IN
), and military COTS (28V
IN
)
applications.
The 4:1 Input Voltage 360 Watt MTW includes trim and
remote ON/OFF. Threaded through holes are provided
to allow easy mounting or addition of a heatsink for
extended temperature operation.
The converters high efficiency and high power density
are accomplished through use of high-efficiency
synchronous rectification technology, advanced
electronic circuit, packaging and thermal design thus
resulting in a high reliability product. Converter
operates at a fixed frequency and follows conservative
component de-rating guidelines.
Product is designed and manufactured in the USA.
Features
• 4:1 Input voltage range
• High power density
• Small size 2.4” x 2.5” x 0.52”
• Efficiency up to 95.6%
• Excellent thermal performance with metal case
• Over-Current and Short Circuit Protection
• Over-Temperature protection
• Auto-restart
• Monotonic startup into pre-bias
• Constant frequency
• Remote ON/OFF
• Good shock and vibration damping
• Extended Temperature Range -55ºC to +105ºC
Available
• RoHS Compliant
• UL60950 Approved
Model Input Range
VDC Vout
VDC Iout
ADC
Min Max
24S12.30MTW (ROHS) 9 36 12 30
24S24.15MTW (ROHS) 9 36 24 15
24S28.13MTW (ROHS) 9 36 28 13
1. Extended Temperature Range of -55ºC to +105ºC is
available. Add “-T” to the part number when ordering.
i.e. 24S12.30MTW-T (ROHS)
2. Negative Logic On/Off feature is available. Add “-N”
to the part number when ordering.
i.e. 24S12.30MTW-N (ROHS)
i.e. 24S12.30MTW-NT (ROHS)
3. Designed to meet MIL-STD-810G for functional shock
and vibration. The unit must be properly secured to the
interface medium (PCB/Chassis) by use of the threaded
inserts of the unit.
4. A thermal management device, such as a heatsink, is
required to ensure proper operation of this device. The
thermal management medium is required to maintain
baseplate < 105ºC for full rated power.
5. Non-standard output voltages are available. Please
contact the factory for additional information.
360
WATT
MTW
SERIES
DC/DC CONVERTERS
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
ECO 161004-1, 170213-2, 170227-1, 170321-1, 170412-2, 170802-
1
Page 2 of
16
Electrical Specifications:
Conditions: T
A
= 25ºC, airflow = 300 LFM (1.5m/s), V
IN
= 24VDC, unless otherwise specified. Specifications subject to change
without notice. All Models
Parameter Notes Min Typ Max Units
Absolute Maximum Ratings
Input Voltage Continuous 0 40 V
Transient (100ms) 50 V
Operating Temperature Baseplate (100% load) -40 105 ºC
Baseplate (100% load) “-T” model -55 105 ºC
Storage Temperature -55 125 ºC
Isolation Characteristics and Safety
Isolation Voltage Input to Output 1500 V
Input to Baseplate & Output to Baseplate 1500 V
Isolation Capacitance 4500 pF
Isolation Resistance 10 20 MΩ
Insulation Safety Rating Basic
Designed to meet UL/cUL 60950, IEC/EN 60950-1
Feature Characteristics
Fixed Switching Frequency Output Voltage Ripple has twice this frequency 200 kHz
Output Voltage Trim Range ±10 %
Remote Sense Compensation This function is not provided N/A %
Output Overvoltage Protection Non-latching 117 124 130 %
Over Temperature Shutdown (Baseplate) Non-latching 110 120 ºC
Auto-Restart Period Applies to all protection features 450 500 550 ms
Turn-On Time from V
IN
Time from UVLO to
V
O
=90% V
OUT
(NOM) Resistive load 517 530 ms
Turn-On time from ON/OFF Control Trim from ON to
V
O
=90% V
OUT
(NOM) Resistive load 17 20 ms
Rise Time VOUT from 10% to 90% 4 7.5 11 ms
ON/OFF Control – Positive Logic
On State Pin open = ON or external voltage applied 2 12 V
Current Control Leakage current 0.16 mA
OFF State 0 0.8 V
Control Current Sinking 0.3 0.36 mA
ON/OFF Control – Negative Logic
ON State Pin shorted to –INPUT or 0.8 V
OFF State Pin open = OFF or 2 12 V
Thermal Characteristics
Thermal resistance Baseplate to Ambient Converter soldered to 3.95” x 2.5” x 0.07”
4 layer / 2oz copper FR4 PCB 5.2 ºC/W
360
WATT
MTW
SERIES
DC/DC CONVERTERS
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
ECO 161004-1, 170213-2, 170227-1, 170321-1, 170412-2, 170802-
1
Page 3 of
16
Electrical Specifications (Continued):
Conditions: T
A
= 25ºC, airflow = 300 LFM (1.5m/s), V
IN
= 24VDC, unless otherwise specified. Specifications subject to change
without notice. 24S12.30MTW
Parameter Notes Min Typ Max Units
Input Characteristics
Operating Input Voltage Range 9 24 36 V
Input Under Voltage Lockout Non-latching
Turn-on Threshold 8.2 8.5 8.8 V
Turn-off Threshold 7.7 8 8.3 V
Lockout Hysteresis Voltage 0.4 0.55 0.7 V
Maximum Input Current V
IN
= 9V, 80% Load 45.3 A
V
IN
= 12V, 100% Load 33.2 A
V
IN
= 24V, Output Shorted 65 mA
RMS
Input Stand-by Current Converter Disabled 2 4 mA
Input Current @ No Load Converter Enabled 240 280 mA
Minimum Input Capacitance (external) ESR < 0.1 Ω 470 µF
Inrush Transient V
IN
= 36V (0.4V/µs) no external input cap 0.4 1 A
2
s
Input Terminal Ripple Current, i
C
25 MHz bandwidth, 100% Load (Fig. 2) 560 mA
RMS
Output Characteristics
Output Voltage Range 11.64 12.00 12.36 V
Output Voltage Set Point Accuracy (50% Load) 11.88 12.00 12.12 V
Output Regulation
Over Line V
IN
= 9V to 36V 0.05 0.15 %
Over Load V
IN
= 24V, Load 0% to 100% 0.08 0.15 %
Temperature Coefficient 0.015 0.03 %/ºC
Over Voltage Protection 14.0 15.6 V
Output Ripple and Noise – 20 MHz bandwidth (Fig. 3) 100% Load 120 180 mV
PK-PK
C
EXT
= 470 µF/70mΩ + 1 µF ceramic 30 60 mV
RMS
External Load Capacitance Full Load (resistive)
-40 ºC < Ta < +105 ºC C
EXT
470 4700 µF
ESR 10 100 mΩ
Output Current Range (See Fig. A) V
IN
= 9V to 36V 0 30 A
Current Limit Inception V
IN
= 9V - 36V 33 36 39 A
RMS Short-Circuit Current Non-latching, Continuous 4 7 A
RMS
Dynamic Response
Load change 50% - 75% - 50%, di/dt = 1A/µs C
o
= 470 µF/70mΩ + 1 µF ceramic ± 200 ± 320 mV
Load change 50% - 100% - 50%, di/dt = 1A/µs C
o
= 470 µF/70mΩ + 1 µF ceramic ± 450 mV
Setting Time to 1% of V
OUT
400 µs
Efficiency
100% Load V
IN
= 24 V 93.7 94.4 95.1 %
V
IN
= 12 V 92.9 93.6 94.3 %
50% Load V
IN
= 24 V 94.1 94.8 95.5 %
V
IN
= 12 V 94 94.7 95.1 %
360
WATT
MTW
SERIES
DC/DC CONVERTERS
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
ECO 161004-1, 170213-2, 170227-1, 170321-1, 170412-2, 170802-
1
Page 4 of
16
Electrical Specifications (Continued):
Conditions: T
A
= 25ºC, airflow = 300 LFM (1.5m/s), V
IN
= 24VDC, unless otherwise specified. Specifications subject to change
without notice. 24S24.15MTW
Parameter Notes Min Typ Max Units
Input Characteristics
Operating Input Voltage Range 9 24 36 V
Input Under Voltage Lockout Non-latching
Turn-on Threshold 8.2 8.5 8.8 V
Turn-off Threshold 7.7 8 8.3 V
Lockout Hysteresis Voltage 0.4 0.55 0.7 V
Maximum Input Current V
IN
= 9V, 80% Load 45 A
V
IN
= 12V, 100% Load 42 A
V
IN
= 24V, Output Shorted 75 mA
RMS
Input Stand-by Current Converter Disabled 2 4 mA
Input Current @ No Load Converter Enabled 240 300 mA
Minimum Input Capacitance (external) ESR < 0.1 Ω 470 µF
Inrush Transient V
IN
= 36V (0.4V/µs) no external input cap 0.4 1 A
2
s
Input Terminal Ripple Current, i
C
25 MHz bandwidth, 100% Load (Fig. 2) 600 mA
RMS
Output Characteristics
Output Voltage Range 23.28 24.00 24.72 V
Output Voltage Set Point Accuracy (50% Load) 23.76 24.00 24.24 V
Output Regulation
Over Line V
IN
= 9V to 36V 0.05 0.15 %
Over Load V
IN
= 24V, Load 0% to 100% 0.08 0.15 %
Temperature Coefficient 0.015 0.03 %/ºC
Over Voltage Protection 28.1 31.2 V
Output Ripple and Noise – 20 MHz bandwidth (Fig. 3) 100% Load 240 360 mV
PK-PK
C
EXT
= 470 µF/70mΩ + 1 µF ceramic 50 80 mV
RMS
External Load Capacitance Full Load (resistive)
-40 ºC < Ta < +105 ºC C
EXT
470 2200 µF
ESR 10 100 mΩ
Output Current Range (See Fig. A) V
IN
= 9V to 36V 0 15 A
Current Limit Inception V
IN
= 9V - 36V 16.5 18 19.5 A
RMS Short-Circuit Current Non-latching, Continuous 3.8 6 A
RMS
Dynamic Response
Load change 50% - 75% - 50%, di/dt = 1A/µs C
o
= 470 µF/70mΩ + 1 µF ceramic ± 280 ± 420 mV
Load change 50% - 100% - 50%, di/dt = 1A/µs C
o
= 470 µF/70mΩ + 1 µF ceramic ± 500 mV
Setting Time to 1% of V
OUT
600 µs
Efficiency
100% Load V
IN
= 24 V 94.5 95.2 95.9 %
V
IN
= 12 V 93.8 94.5 95.2 %
50% Load V
IN
= 24 V 94.5 95.4 96.1 %
V
IN
= 12 V 94.6 95.2 95.9 %
360
WATT
MTW
SERIES
DC/DC CONVERTERS
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
ECO 161004-1, 170213-2, 170227-1, 170321-1, 170412-2, 170802-
1
Page 5 of
16
Electrical Specifications (Continued):
Conditions: T
A
= 25ºC, airflow = 300 LFM (1.5m/s), V
IN
= 24VDC, unless otherwise specified. Specifications subject to change
without notice. 24S28.13MTW
Parameter Notes Min Typ Max Units
Input Characteristics
Operating Input Voltage Range 9 24 36 V
Input Under Voltage Lockout Non-latching
Turn-on Threshold 8.2 8.5 8.8 V
Turn-off Threshold 7.7 8 8.3 V
Lockout Hysteresis Voltage 0.4 0.55 0.7 V
Maximum Input Current V
IN
= 9V, 80% Load 45 A
V
IN
= 12V, 100% Load 42 A
V
IN
= 24V, Output Shorted 55 mA
RMS
Input Stand-by Current Converter Disabled 2 4 mA
Input Current @ No Load Converter Enabled 240 280 mA
Minimum Input Capacitance (external) ESR < 0.1 Ω 470 µF
Inrush Transient V
IN
= 36V (0.4V/µs) no external input cap 0.4 1 A
2
s
Input Terminal Ripple Current, i
C
25 MHz bandwidth, 100% Load (Fig. 2) 560 mA
RMS
Output Characteristics
Output Voltage Range 27.16 28.00 28.84 V
Output Voltage Set Point Accuracy (50% Load) 27.72 28.00 28.28 V
Output Regulation
Over Line V
IN
= 9V to 36V 0.05 0.15 %
Over Load V
IN
= 24V, Load 0% to 100% 0.08 0.15 %
Temperature Coefficient 0.015 0.03 %/ºC
Over Voltage Protection 32.8 36.4 V
Output Ripple and Noise – 20 MHz bandwidth (Fig. 3) 100% Load 280 380 mV
PK-PK
C
EXT
= 470 µF/70mΩ + 1 µF ceramic 50 85 mV
RMS
External Load Capacitance Full Load (resistive)
-40 ºC < Ta < +105 ºC C
EXT
470 2200 µF
ESR 10 100 mΩ
Output Current Range (See Fig. A) V
IN
= 9V to 36V 0 13 A
Current Limit Inception V
IN
= 9V - 36V 14.3 15.6 16.9 A
RMS Short-Circuit Current Non-latching, Continuous 2.2 6 A
RMS
Dynamic Response
Load change 50% - 75% - 50%, di/dt = 1A/µs C
o
= 470 µF/70mΩ + 1 µF ceramic ± 180 ± 300 mV
Load change 50% - 100% - 50%, di/dt = 1A/µs C
o
= 470 µF/70mΩ + 1 µF ceramic ± 400 mV
Setting Time to 1% of V
OUT
500 µs
Efficiency
100% Load V
IN
= 24 V 94.3 95.4 96.1 %
V
IN
= 12 V 93.7 94.4 95.1 %
50% Load V
IN
= 24 V 94.3 95.0 95.7 %
V
IN
= 12 V 94.0 94.7 95.1 %
360
WATT
MTW
SERIES
DC/DC CONVERTERS
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
ECO 161004-1, 170213-2, 170227-1, 170321-1, 170412-2, 170802-
1
Page 6 of
16
Environmental and Mechanical Specifications:
Specifications subject to change without notice.
Parameter Notes Min Typ Max Units
Environmental
Operating Humidity Non-condensing 95 %
Storage Humidity Non-condensing 95 %
ROHS Compliance
1
See Calex Website http://www.calex.com/RoHS.html for the complete RoHS Compliance
Statement
Shock and Vibration Designed to meet MIL-STD-810G for functional shock and vibration
Water Washability Not recommended for water wash process. Contact the factory for more information.
Mechanical
Weight 3.85 Ounces
109.2 Grams
PCB
Operating Temperature 130 ºC
Tg 170 ºC
Through Hole Pin Diameters
Pins 1 ,4, 5 and 9 0.079 0.081 0.083 Inches
2.006 2.057 2.108 mm
Pins 3 and 7 0.038 0.04 0.042 Inches
0.965 1.016 1.067 mm
Through Hole Pin Material Pins 1,4,5 and 9 C14500 or C1100 Copper Alloy
Pins 3 and 7 Brass Alloy TB3 or “Eco Brass”
Through Hole Pin Finish All pins 10µ” Gold over Nickel
Case Dimensions 2.4 x 2.5 x 0.52 Inches
60.96 x 63.50 x 13.21 mm
Case Material Plastic: Vectra LCP FIT30: ½ - 16 EDM Finish
Baseplate
Material Aluminum
Flatness 0.008 Inches
0.20 mm
Reliability
MTBF Telcordia SR-332, Method 1 Case 1 50%
electrical stress, 40ºC components 5.4 MHrs
Agency Approvals UL60950
EMI and Regulatory Compliance
Conducted Emissions MIL-STD-461F CE102 with external EMI filter network (see Figs, 28 and 29)
Additional Notes:
1. the RoHS marking is as follows:
Figure A: Output Power as function of input voltage.
360
WATT
MTW
SERIES
DC/DC CONVERTERS
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
ECO 161004-1, 170213-2, 170227-1, 170321-1, 170412-2, 170802-
1
Page 7 of
16
Operations:
Input and Output Capacitance
In many applications, the inductance associated with the
distribution from the power source to the input of the
converter can affect the stability of the converter. This
becomes of great consideration for input voltage at 12V
or below. In order to enable proper operation of the
converter, in particular during load transients, an
additional input capacitor is required. Minimum required
input capacitance, mounted close to the input pins, is
1000µF with ESR < 0.1 Ω. Since inductance of the input
power cables could have significant voltage drop due to
rate of change of input current di(in)/dt during transient
load operation an external capacitance on the output of
the converter is required to reduce di(in)/dt. It is required
to use at least 470 µF (ESR < 0.07Ω) on the output.
Another constraint is minimum rms current rating of the
input and output capacitors which is application
dependent. One component of input rms current handled
by input capacitor is high frequency component at
switching frequency of the converter (typ. 400kHz) and
is specified under “Input terminal ripple current” ic.
Typical values at full rated load and 24 Vin are provided
in Section “Characteristic Waveforms” for each model
and are in range of 0.56A - 0.6A. Second component of
the ripple current is due to reflected step load current on
the input of the converter. Similar consideration needs to
be taken into account for output capacitor and in particular
step load ripple current component. Consult the factory
for further application guidelines.
Additionally, for EMI conducted measurement it is
necessary to use 5µH LISNs instead of typical 50µH
LISNs.
ON/OFF (Pin 3)
The ON/OFF pin is used to turn the power converter on
or off remotely via a system signal and has positive logic.
A typical connection for remote ON/OFF function is
shown in Fig. 1.
The positive logic version turns on when the ON/OFF pin
is at logic high and turns off when at logic low. The
converter is on when the ON/OFF pin is either left open or
external voltage not more than 12V is applied between
ON/OFF pin and -INPUT pin. See the Electrical
Specifications for logic high/low definitions.
The negative logic version turns on when the ON/OFF pin
is at logic low and turns off when at logic high. The
converter is on when the ON/OFF pin is either shorted to
-INPUT pin or kept below 0.8V. The converter is off when
the ON/OFF pin is either left open or external voltage
greater than 2V and not more than 12V is applied
between ON/OFF pin and -INPUT pin. See the Electrical
Specifications for logic high/low definitions.
The ON/OFF pin is internally pulled up to typically 4.5V
via resistor and connected to internal logic circuit via RC
circuit in order to filter out noise that may occur on the
ON/OFF pin. A properly de-bounced mechanical switch,
open-collector transistor, or FET can be used to drive the
input of the ON/OFF pin. The device must be capable of
sinking up to 0.36mA at a low level voltage of < 0.8V.
During logic high, the typical maximum voltage at
ON/OFF pin (generated by the converter) is 4.5V, and the
maximum allowable leakage current is 160µA. If not
using the remote on/off feature leave the ON/OFF pin
open.
TTL Logic Level - The range between 0.81V as maximum
turn off voltage and 2V as minimum turn on voltage is
considered the dead-band. Operation in the dead-band is
not recommended.
External voltage for ON/OFF control should not be
applied when there is no input power voltage applied to
the converter.
Protection Features:
Input Undervoltage lockout (UVLO)
Input undervoltage lockout is standard with this converter.
The converter will shut down when the input voltage
drops below a pre-determined voltage.
The input voltage must be typically above 8.5V for the
converter to turn on. Once the converter has been turned
on, it will shut off when the input voltage drops typically
below 8V. If the converter is started by input voltage
(ON/OFF (pin 3) left open) there is typically 500msec
delay from the moment when input voltage is above 8.5V
turn-on voltage and the time when output voltage starts
rising. This delay is intentionally provided to prevent
potential startup issues especially at low input voltages.
Output Overcurrent Protection (OCP)
The converter is protected against overcurrent or short
circuit conditions. Upon sensing an overcurrent
condition, the converter will switch to constant current
operation and thereby begin to reduce output voltage.
When the output voltage drops below approx. 75% of the
360
WATT
MTW
SERIES
DC/DC CONVERTERS
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
ECO 161004-1, 170213-2, 170227-1, 170321-1, 170412-2, 170802-
1
Page 8 of
16
nominal value of output voltage, the converter will shut
down. Once the converter has shut down, it will attempt
to restart nominally every 500msec with a typical 3% duty
cycle. The attempted restart will continue indefinitely until
the overload or short circuit conditions are removed or
the output voltage rises above 75% of its nominal value.
Once the output current is brought back into its specified
range, the converter automatically exits the hiccup mode
and continues normal operation.
During initial startup, if output voltage does not exceed
typical 75% of nominal output voltage within 20 msec
after the converter is enabled, the converter will be shut
down and will attempt to restart after 500 msec.
Output Overvoltage Protection (OVP)
The converter will shut down if the output voltage across
V
OUT
(+) (Pin 5) and V
OUT
(-) (Pin 9) exceeds the
threshold of the OVP circuitry. The OVP circuitry
contains its own reference, independent of the output
voltage regulation loop. Once the converter has shut
down, it will attempt to restart every 500 msec until the
OVP condition is removed.
Over Temperature Protection (OTP)
The MTW converters have non-latching over temperature
protection. It will shut down and disable the output if
temperature at the center of the base place exceeds a
threshold of 114ºC (typical).
The converter will automatically restart when the base
temperature has decreased by approximately 20ºC.
Safety Requirements
Basic Insulation is provided between input and the
output.
The converters have no internal fuse. To comply with
safety agencies requirements, a fast-acting or time-delay
fuse is to be provided in the unearthed lead.
Recommended fuse values are:
a) 50A for 9V < V
IN
< 18V
a) 25A for 18V < V
IN
< 36V
Electromagnetic Compatibility (EMC)
EMC requirements must be met at the end-product
system level, as no specific standards dedicated to EMC
characteristics of board mounted component dc-dc
converters exist.
With the addition of a single stage external filter, the
MTW converters will pass the requirements of MIL-STD-
461F CE102 Base Curve for conducted emissions.
Absence of the Remote Sense Pins
Customers should be aware that MTW converters do not
have a Remote Sense feature. Care should be taken to
minimize voltage drop on the user’s motherboard as well
as if trim function is used.
Output Voltage Adjust/TRIM (Pin 7)
The TRIM pin allows user to adjust output voltage 10%
up or down relative to rated nominal voltage by addition
of external trim resistor. Due to absence of Remote
Sense Pins, an external trim resistor should be
connected to output pins using Kelvin connection. If
trimming is not used, the TRIM pin should be left open.
Trim Down – Decrease Output Voltage
Trimming down is accomplished by connecting an
external resistor, Rtrim-down, between the TRIM (pin 7)
and the V
OUT
(-) (pin 9) using Kelvin connection, with a
value of:
R
trim-down =
∆
Where,
Rtrim-down= Required value of the trim-down resistor [kΩ]
V
O
(nom) = Nominal value of output voltage [V]
V
O
(req) = Required value of output voltage [V]
∆ =
To trim the output voltage 10% (∆=10) down, required
external trim resistance is.
R
trim-down =
10
kΩ
Trim Up – Increase Output Voltage
Trimming up is accomplished by connecting an external
resistor, Rtrim-up, between the TRIM (pin 7) and the
V
OUT
(+) (pin5) using Kelvin connection, with a value of:
R
trim-up = !"#
$%
&
'%(
)
! *+
,+
-
*+
+
.
[kΩ]
To trim the output voltage up, for example 24V to 26.4V,
∆=10 and required external resistor is:
R
trim-up =
! "#
/0!1
//2!
-
1/!
. ,
kΩ
Note that trimming output voltage more than 10% is not
recommended and OVP may be tripped.
360
WATT
MTW
SERIES
DC/DC CONVERTERS
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
ECO 161004-1, 170213-2, 170227-1, 170321-1, 170412-2, 170802-
1
Page 9 of
16
Active Voltage Programming
In applications where output voltage needs to be adjusted
actively, an external voltage source, such as for example
a Digital-to-Analog converter (DAC), capable of both
sourcing and sinking current can be used. It should be
connected with series resister Rg across TRIM (pin 7)
and VOUT(-) (pin 9) using Kelvin connection. Please
contact Calex technical representative for more details.
Thermal Consideration
The MTW converter can operate in a variety of thermal
environments. However, in order to ensure reliable
operation of the converter, sufficient cooling should be
provided. The MTW converter is encapsulated in plastic
case with metal baseplate on the top. In order to improve
thermal performance, power components inside the unit
are thermally coupled to the baseplate. In addition,
thermal design of the converter is enhanced by use of
input and out pins as heat transfer elements. Heat is
removed from the converter by conduction, convection
and radiation.
There are several factors such as ambient temperature,
airflow, converter power dissipation, converter orientation
how converter is mounted as well as the need for
increased reliability that need to be taken into account in
order to achieve required performance. It is highly
recommended to measure temperature in the middle of
the baseplate in particular application to ensure that
proper cooling of the convert is provided.
A reduction in the operating temperature of the converter
will result in an increased reliability.
Thermal Derating
There are two most common applications: 1) the MTW
converter is thermally attached to a cold plate inside
chassis without any forced internal air circulation; 2) the
MTW converter is mounted in an open chassis on system
board with forced airflow with or without an additional
heatsink attached to the baseplate of the MTW converter.
The best thermal results are achieved in application 1)
since the converter is cooled entirely by conduction of
heat from the top surface of the converter to a cold plate
and temperature of the components is determined by the
temperature of the cold plate. There is also some
additional heat removal through the converters pins to the
metal layers in the system board. It is highly
recommended to solder pins to the system board rather
than using receptacles. Typical derating output power
and current are shown in Figs. 10–15 for various
baseplate temperatures up to 105ºC. The converter was
solder to the test card: 4.26” x 5.9” 4 layers FR4 PCB with
3Oz Cu inner layers and 2 Oz Cu outer layers, covered
with solder mask. Note that operating converter at these
limits for prolonged time will affect reliability.
Soldering Guidelines
The ROHS-compliant through hole MTW converters use
Sn/Ag/Cu Pb-free solder and ROHS compliant
components. They are designed to be processed through
wave soldering machines. The pins are 100% matte tin
over nickel plated and compatible with both Pb and Pb-
free wave soldering processes. It is recommended to
follow specifications below when installing and soldering
MTW converters. Exceeding these specifications may
cause damage to the MTW converter.
Wave Solder Guideline for Sn/Ag/Cu based solders
Maximum Preheat Temperature 115ºC
Maximum Pot Temperature 270ºC
Maximum Solder Dwell Time 7 seconds
Wave Solder Guideline for SN/Pb based solders
Maximum Preheat Temperature 105ºC
Maximum Pot Temperature 250ºC
Maximum Solder Dwell Time 6 seconds
MTW converters are not recommended for water wash
process. Contact the factory for additional information if
water wash is necessary.
Fig. 2: Test setup for measuring input reflected ripple currents i
C
and i
S.
Fig. 3: Test setup for measuring output voltage ripple, startup
and step load transient waveforms.
360
WATT
MTW
SERIES
DC/DC CONVERTERS
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
ECO 161004-1, 170213-2, 170227-1, 170321-1, 170412-2, 170802-
1
Page 10 of
16
Characteristic Curves – Efficiency and Power Dissipation
Fig. 4: 24S12.30MTW (ROHS) Efficiency Curve
Fig. 6: 24S24.15MTW (ROHS) Efficiency Curve
Fig. 8: 24S28.13MTW (ROHS) Efficiency Curve
Fig. 5 24S12.30MTW (ROHS) Power Dissipation
Fig. 7: 24S24.15MTW (ROHS) Power Dissipation
Fig. 9: 24S28.13MTW (ROHS) Power Dissipation
360
WATT
MTW
SERIES
DC/DC CONVERTERS
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
ECO 161004-1, 170213-2, 170227-1, 170321-1, 170412-2, 170802-
1
Page 11 of
16
Characteristic Curves – Derating vs. Baseplate Temperature
Fig. 10: 24S12.30MTW (ROHS) Derating Curve
Fig. 12: 24S24.15MTW (ROHS) Derating Curve
Fig. 14: 24S28.13MTW (ROHS) Derating Curve
Fig. 11: 24S12.30MTW (ROHS) Derating Curve
Fig. 13: 24S24.15MTW (ROHS) Derating Curve
Fig.15: 24S28.13MTW (ROHS) Derating Curve
0
60
120
180
240
300
360
420
25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105
Output Power [W]
Baseplate Temperature [C]
Output Power vs. Base Plate Temperature - 24S12.30MTW
Vin=9V Vin=12V -36V
0
60
120
180
240
300
360
420
25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105
Output Power [W]
Baseplate Temperature [C]
Output Power vs. Base Plate Temperature - 24S24.15MTW
Vin=9V Vin=12V - 36V
0
60
120
180
240
300
360
420
25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105
Output Power [W]
Baseplate Temperature [C]
Output Power vs. Baseplate Temperature - 24S28.13MTW
Vin=9V Vin=12V - 36V
0
5
10
15
20
25
30
35
25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105
Output Current [W]
Baseplate Temperature [C]
Output Current vs. Base Plate Temperature - 24S12.30MTW
Vin=9V Vin=12V - 36V
0
2.5
5
7.5
10
12.5
15
17.5
25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105
Output Current [W]
Baseplate Temperature [C]
Output Current vs. Base Plate Temperature - 24S24.15MTW
Vin=9V Vin=12V Vin=24V - 36V
0
2
4
6
8
10
12
14
16
25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105
Output Power [W]
Baseplate Temperature [C]
Output Current vs. Base Plate Temperature - 24S28.13MTW
Vin=9V Vin=12V - 36V
360
WATT
MTW
SERIES
DC/DC CONVERTERS
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
ECO 161004-1, 170213-2, 170227-1, 170321-1, 170412-2, 170802-
1
Page 12 of
16
Characteristic Waveforms – 24S12.30MTW (ROHS)
Fig. 16: Turn-on by ON/OFF transient (with V
IN
applied) at full rated load
current (resistive) at V
IN
= 24V. Top trace (C1): ON/OFF signal
(5V/div.). Bottom trace (C4): Output voltage (5 V/div.). Time 5 ms/div.
Fig. 18: Output voltage response to load current step change 50% -
75% - 50% (15A – 22.5A – 15A) with di/dt = 1A/µs at V
IN
= 24V. Top
trace (C4): Output voltage (200 mV/div.). Bottom trace (C3): Load
current (20A/div.). C
O
470µF/70mΩ. Time: 1ms/div.
Fig. 20: Output voltage ripple (100mv/div.) at full rated load current into
a resistive load at V
IN
= 24V. C
O
470µF/70mΩ. Time: 2µs/div.
Fig. 17: Turn-on by V
IN
(ON/OFF high) transient at full rated load
current (resistive) at V
IN
= 24V. Top trace (C2): Input voltage V
IN
(10
V/div.). Bottom trace (C4): Output voltage (5 V/div.). Time 100 ms/div.
Fig. 19: Output voltage response to load current step change 50% -
100% - 50% (15A – 30A – 15A) with di/dt = 1A/µs at V
IN
= 24V. Top
trace (C4): Output voltage (500 mV/div.). Bottom trace (C3): Load
current (20A/div.). C
O
470µF/70mΩ. Time: 1ms/div.
Fig. 21: Input reflected ripple current, i
C
(500 mA/mV), measured at
input terminals at full rated load current at V
IN
= 24V. Refer to Fig. 2 for
test setup. Time: 2 µs/div. RMS input ripple current is 1.125*500mA =
560mA.
360
WATT
MTW
SERIES
DC/DC CONVERTERS
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
ECO 161004-1, 170213-2, 170227-1, 170321-1, 170412-2, 170802-
1
Page 13 of
16
Characteristic Waveforms – 24S24.15MTW (ROHS)
Fig. 22: Turn-on by ON/OFF transient (with V
IN
applied) at full rated load
current (resistive) at V
IN
= 24V. Top trace (C1): ON/OFF signal
(5V/div.). Bottom trace (C4): Output voltage (10 V/div.). Time 5 ms/div.
Fig. 24: Output voltage response to load current step change 50% -
75% - 50% (7.5A – 11.25A – 7.5A) with di/dt = 1A/µs at V
IN
= 24V. Top
trace (C4): Output voltage (200 mV/div.). Bottom trace (C3): Load
current (10A/div.). C
O
470µF/70mΩ. Time: 1ms/div.
Fig. 26: Output voltage ripple (200mv/div.) at full rated load current into
a resistive load at V
IN
= 24V. C
O
470µF/70mΩ. Time: 2µs/div.
Fig. 23: Turn-on by V
IN
transient (ON/OFF high) at full rated load current
(resistive) at V
IN
= 24V. Top trace (C2): Input voltage V
IN
(10 V/div.).
Bottom trace (C4): Output voltage (10 V/div.). Time 100 ms/div.
Fig. 25: Output voltage response to load current step change 50% -
100% - 50% (7.5A – 15A – 7.5A) with di/dt = 1A/µs at V
IN
= 24V. Top
trace (C4): Output voltage (500 mV/div.). Bottom trace (C3): Load
current (10A/div.). C
O
470µF/70mΩ. Time: 1ms/div.
Fig. 27: Input reflected ripple current, i
C
(500 mA/mV), measured at
input terminals at full rated load current at V
IN
= 24V. Refer to Fig. 2 for
test setup. Time: 2 µs/div. RMS input ripple current is 1.205*500mA =
602.5mA.
360
WATT
MTW
SERIES
DC/DC CONVERTERS
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
ECO 161004-1, 170213-2, 170227-1, 170321-1, 170412-2, 170802-
1
Page 14 of
16
Characteristic Waveforms – 24S28.13MTW (ROHS)
Fig. 28: Turn-on by ON/OFF transient (with V
IN
applied) at full rated load
current (resistive) at V
IN
= 24V. Top trace (C1): ON/OFF signal
(5V/div.). Bottom trace (C4): Output voltage (10 V/div.). Time 5 ms/div.
Fig. 30: Output voltage response to load current step change 50% -
75% - 50% (6.5A – 9.75A – 6.5A) with di/dt = 1A/µs at V
IN
= 24V. Top
trace (C4): Output voltage (200 mV/div.). Bottom trace (C3): Load
current (10A/div.). C
O
470µF/70mΩ. Time: 1ms/div.
Fig.32: Output voltage ripple (200mv/div.) at full rated load current into a
resistive load at V
IN
= 24V. C
O
470µF/70mΩ. Time: 2µs/div.
Fig. 29: Turn-on by V
IN
transient (ON/OFF high) at full rated load current
(resistive) at V
IN
= 24V. Top trace (C2): Input voltage V
IN
(10 V/div.).
Bottom trace (C4): Output voltage (10 V/div.). Time 100 ms/div.
Fig. 31: Output voltage response to load current step change 50% -
100% - 50% (6.5A – 13A – 6.5A) with di/dt = 1A/µs at V
IN
= 24V. Top
trace (C4): Output voltage (500 mV/div.). Bottom trace (C3): Load
current (10A/div.). C
O
470µF/70mΩ. Time: 1ms/div.
Fig. 33: Input reflected ripple current, i
C
(500 mA/mV), measured at
input terminals at full rated load current at V
IN
= 24V. Refer to Fig. 2 for
test setup. Time: 2 µs/div. RMS input ripple current is 0.935*500mA =
549mA.
360
WATT
MTW
SERIES
DC/DC CONVERTERS
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
ECO 161004-1, 170213-2, 170227-1, 170321-1, 170412-2, 170802-
1
Page 15 of
16
EMC Consideration:
The filter schematic for suggested input filter configuration as tested to meet the conducted emission limits of MIL-
STD-461F CE102 Base Curve is shown in Fig.34. The plots of conducted EMI spectrum are shown in Fig. 35.
Note: Customer is ultimately responsible for the proper selection, component rating and verification of the suggested
parts based on the end application.
Comp. Des. Description
C1, C2, C12, C14 470µF/50V/70mΩ Electrolytic Capacitor (Vishay MAL214699108E3 or equivalent)
C3, C4, C5, C6 4.7nF/1210/X7R/1500V Ceramic Capacitor
C7, C8, C9, C10, C11, C13 10µF/1210/X7R/50V Ceramic Capacitor
L1 CM choke: L = 130µH, L
lkg
= 0.6µH (4 turns on toroid 22.1mm x 13.7mm x 7.92mm)
Fig.34: Typical input EMI filter circuit to attenuate conducted emissions per MIL-STD-461F CE102 Base Curve.
a) Without input filter. C
IN
= 2 x 470µF/50V/70mΩ.
b) With input filter from Fig. 28.
Fig. 35: Input conducted emissions measurement (Typ.) of 24S24.15MTW (ROHS)
360
WATT
MTW
SERIES
DC/DC CONVERTERS
2401 Stanwell Drive, Concord Ca. 94520 Ph: 925-687-4411 Fax: 925-687-3333 www.calex.com Email: sales@calex.com
ECO 161004-1, 170213-2, 170227-1, 170321-1, 170412-2, 170802-
1
Page 16 of
16
Mechanical Specification:
Notes:
Unless otherwise specified:
All dimensions are in inches [millimeters]
Tolerances: x.xx in. ±0.02 in [x.x mm ±0.5mm]
x.xxx in. ±0.010 in [x.xx mm ±0.25mm]
Torque fasteners into threaded mounting inserts at
10in.lbs. or less. Greater torque may result in damage to
unit and void the warranty.
Input Output Connections:
Pin Name Function
1 -INPUT Negative input voltage
3 ON/OFF TTL input with internal pull up,
referenced to –INPUT, used to turn
converter on and off
4 +INPUT Positive input voltage
5 +OUTPUT Positive output voltage
7 TRIM Output voltage trim
9 -OUTPUT Negative output voltage
Notes:
1) Pinout is inconsistent between manufacturers of the half brick
converters. Make sure to follow the pin function, the pin number, when
laying out your board.
2) Pin diameter for the input pins of the MTW converters has diameter
0.081” due to high current at low line, and is different from other
manufacturers of the half brick. Make sure to follow pin dimensions in
your application.
