24S24.21MXW (ROHS) - CALEX - Product.Network

2401 Stanwell Drive, Concord Ca. 94520,

Ph: 925-687-4411, Fax: 925-687-3333,

www.calex.com Email: sales@calex.com

Page 1 of 17

500 WATT MXW SERIES

DC/DC CONVERTER

ECO 171121-1, 181204-1

· 4:1 Input voltage range

· High power density

· Small size 2.4” x 2.5” x 0.52”

· Efficiency up to 95.7%

· Excellent thermal performance

· Metal Baseplate

· 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

· Temperature Range -40ºC to +105ºC Available

· RoHS Compliant

· UL60950 Approved

· 5 Year Warranty

Product Overview

The 4:1 Input Voltage 500 Watt Single MXW 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 500 Watt

MXW meets the most rigorous performance standards

in an industry standard footprint for mobile (12VIN),

process control (24VIN), and military COTS (28VIN)

applications.

The 4:1 Input Voltage 500 Watt MXW includes trim and

remote ON/OFF. Threaded through holes are provided

to allow easy mounting or addition of a heatsink for

extended temperature operation. (Non-threaded option

is available, see ordering information under model

selection table.)

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.

Model

Input Range

VDC Vout

VDC

Iout

ADC

Min Max

24S12.41MXW (ROHS) 9 36 12 41

24S24.21MXW (ROHS) 9 36 24 21

24S28.18MXW (ROHS) 9 36 28 18

1. Negative Logic On/Off feature is available. Add “-N” to the

part number when ordering.

i.e. 24S12.41MXW-N (ROHS)

2. Available with non-threaded mounting inserts. Add –I to the

part number when ordering.

i.e 24S28.18MXW-I (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.

2401 Stanwell Drive, Concord Ca. 94520,

Ph: 925-687-4411, Fax: 925-687-3333,

www.calex.com Email: sales@calex.com

Page 2 of 17

500 WATT MXW SERIES

DC/DC CONVERTER

ECO 171121-1, 181204-1

Electrical Specifications:

Conditions: TA = 25ºC, airflow = 300 LFM (1.5m/s), VIN = 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

Storage Temperature -55 125 ºC

Isolation Characteristics and Safety

Isolation Voltage Input to Output 2250 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 VIN Time from UVLO to

VO=90% VOUT (NOM) Resistive load

517 530 ms

Turn-On time from ON/OFF Control Trim from ON to

VO=90% VOUT (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

2401 Stanwell Drive, Concord Ca. 94520,

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Page 3 of 17

500 WATT MXW SERIES

DC/DC CONVERTER

ECO 171121-1, 181204-1

Electrical Specifications (Continued):

Conditions: TA = 25ºC, airflow = 300 LFM (1.5m/s), VIN = 24VDC, unless otherwise specified. Specifications subject to change

without notice.

24S12.41MXW

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 VIN = 9V, 80% Load 50.4 A

VIN = 12V, 100% Load 46.2 A

VIN = 24V, Output Shorted 65 mARMS

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 Vin = 36V (0.4V/µs) no input external capacitor 0.4 1 A2s

Input Terminal Ripple Current, iC 25 MHz bandwidth, 100% Load (Fig. 2) 620 mARMS

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 VIN = 9V to 36V 0.05 0.15 %

Over Load VIN = 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 mVPK-PK

CEXT = 470 µF/70mΩ + 1 µF ceramic 30 60 mVRMS

External Load Capacitance Full Load (resistive)

-40 ºC < Ta < +105 ºC

CEXT 470 4700 µF

ESR 10 100 mΩ

Output Current Range (See Fig. A) VIN = 12V to 36V 0 41 A

VIN = 9 V 0 33.3 A

Current Limit Inception VIN = 12V - 36V 45.1 49.2 53.3 A

9V < VIN < 12V 40.6 53.3 A

RMS Short-Circuit Current Non-latching, Continuous 4 7 ARMS

Dynamic Response

Load change 50% - 75%, di/dt = 1A/µs Co = 470 µF/70mΩ + 1 µF ceramic ± 320 ± 450 mV

Load change 50% - 100%, di/dt = 1A/µs Co = 470 µF/70mΩ + 1 µF ceramic ± 700 mV

Setting Time to 1% of VOUT 600 µs

Efficiency: 100% Load VIN = 24 V 93.2 93.9 94.6 %

VIN = 12 V 91.4 92.1 92.8 %

Efficiency: 50% Load VIN = 24 V 94.7 95.4 96.1 %

VIN = 12 V 93.9 94.6 95.2 %

2401 Stanwell Drive, Concord Ca. 94520,

Ph: 925-687-4411, Fax: 925-687-3333,

www.calex.com Email: sales@calex.com

Page 4 of 17

500 WATT MXW SERIES

DC/DC CONVERTER

ECO 171121-1, 181204-1

Electrical Specifications (Continued):

Conditions: TA = 25ºC, airflow = 300 LFM (1.5m/s), VIN = 24VDC, unless otherwise specified. Specifications subject to change

without notice.

24S24.21MXW

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 VIN = 9V, 80% Load 50.4 A

VIN = 12V, 100% Load 47.0 A

VIN = 24V, Output Shorted 75 mARMS

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 Vin = 36V (0.4V/µs) no input external capacitor 0.4 1 A2s

Input Terminal Ripple Current, iC 25 MHz bandwidth, 100% Load (Fig. 2) 680 mARMS

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 VIN = 9V to 36V 0.05 0.15 %

Over Load VIN = 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 mVPK-PK

CEXT = 470 µF/70mΩ + 1 µF ceramic 50 80 mVRMS

External Load Capacitance Full Load (resistive)

-40 ºC < Ta < +105 ºC

CEXT 470 2200 µF

ESR 10 100 mΩ

Output Current Range (See Fig. A) VIN = 12V to 36V 0 21 A

VIN = 9 V 0 16.7 A

Current Limit Inception VIN = 12V - 36V 23.1 25.2 27.3 A

9V < VIN < 12V 20.8 27.3 A

RMS Short-Circuit Current Non-latching, Continuous 3.8 6 ARMS

Dynamic Response

Load change 50% - 75%, di/dt = 1A/µs Co = 470 µF/70mΩ + 1 µF ceramic ± 280 ± 420 mV

Load change 50% - 100%, di/dt = 1A/µs Co = 470 µF/70mΩ + 1 µF ceramic ± 500 mV

Setting Time to 1% of VOUT 600 µs

Efficiency: 100% Load VIN = 24 V 93.6 94.3 95 %

VIN = 12 V 92.3 93.0 93.7 %

Efficiency: 50% Load VIN = 24 V 94.5 95.4 96.3 %

VIN = 12 V 94.5 95.2 95.9 %

2401 Stanwell Drive, Concord Ca. 94520,

Ph: 925-687-4411, Fax: 925-687-3333,

www.calex.com Email: sales@calex.com

Page 5 of 17

500 WATT MXW SERIES

DC/DC CONVERTER

ECO 171121-1, 181204-1

Electrical Specifications (Continued):

Conditions: TA = 25ºC, airflow = 300 LFM (1.5m/s), VIN = 24VDC, unless otherwise specified. Specifications subject to change

without notice.

24S28.18MXW

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 VIN = 9V, 80% Load 50.4 A

VIN = 12V, 100% Load 46.2 A

VIN = 24V, Output Shorted 55 mARMS

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 Vin = 36V (0.4V/µs) no input external capacitor 0.4 1 A2s

Input Terminal Ripple Current, iC 25 MHz bandwidth, 100% Load (Fig. 2) 550 mARMS

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 VIN = 9V to 36V 0.05 0.15 %

Over Load VIN = 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 mVPK-PK

CEXT = 470 µF/70mΩ + 1 µF ceramic 50 85 mVRMS

External Load Capacitance Full Load (resistive)

-40 ºC < Ta < +105 ºC

CEXT 470 2200 µF

ESR 10 100 mΩ

Output Current Range (See Fig. A) VIN = 12V to 36V 0 18 A

VIN = 9 V 0 14.3 A

Current Limit Inception VIN = 12V - 36V 19.8 23.4 A

9V < VIN < 12V 17.8 23.4 A

RMS Short-Circuit Current Non-latching, Continuous 2.2 6 ARMS

Dynamic Response

Load change 50% - 75%, di/dt = 1A/µs Co = 470 µF/70mΩ + 1 µF ceramic ± 270 ± 410 mV

Load change 50% - 100%, di/dt = 1A/µs Co = 470 µF/70mΩ + 1 µF ceramic ± 500 mV

Setting Time to 1% of VOUT 800 µs

Efficiency: 100% Load VIN = 24 V 94.3 95.0 95.7 %

VIN = 12 V 93.1 93.8 94.5 %

Efficiency: 50% Load VIN = 24 V 95.0 95.7 96.4 %

VIN = 12 V 94.1 94.8 95.5 %

2401 Stanwell Drive, Concord Ca. 94520,

Ph: 925-687-4411, Fax: 925-687-3333,

www.calex.com Email: sales@calex.com

Page 6 of 17

500 WATT MXW SERIES

DC/DC CONVERTER

ECO 171121-1, 181204-1

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 Approved

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:

Fig. A : Output Power vs. Input Voltage

0

100

200

300

400

500

600

912 15 18 21 24 27 30 33 36

Output Power [W]

Input Voltage [V]

Output Power vs. Input Voltage

2401 Stanwell Drive, Concord Ca. 94520,

Ph: 925-687-4411, Fax: 925-687-3333,

www.calex.com Email: sales@calex.com

Page 7 of 17

500 WATT MXW SERIES

DC/DC CONVERTER

ECO 171121-1, 181204-1

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 0.55A - 0.7A. 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.

2401 Stanwell Drive, Concord Ca. 94520,

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Page 8 of 17

500 WATT MXW SERIES

DC/DC CONVERTER

ECO 171121-1, 181204-1

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 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 VOUT (+) (Pin 5) and VOUT (-) (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 MXW 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 112ºC (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) 60A for 9V < VIN < 18V

a) 30A for 18V < VIN < 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

MXW 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 MXW 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 VOUT(-) (pin 9) using Kelvin connection, with

a value of:

Rtrim-down = 󰇡

∆−60.2󰇢[kΩ]

Where,

Rtrim-down= Required value of the trim-down resistor

[kΩ]

VO (nom) =

Nominal value of output voltage

[V]

VO (req) =

Required value of output voltage

[V]

∆ = 󰇻()()

()󰇻[%]

To trim the output voltage 10% (∆=10) down,

required external trim resistance is.

Rtrim-down = 󰇡

10 −60.2󰇢 = 240.8 kΩ

2401 Stanwell Drive, Concord Ca. 94520,

Ph: 925-687-4411, Fax: 925-687-3333,

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Page 9 of 17

500 WATT MXW SERIES

DC/DC CONVERTER

ECO 171121-1, 181204-1

Trim Up – Increase Output Voltage

Trimming up is accomplished by connecting an

external resistor, Rtrim-up, between the TRIM (pin 7)

and the VOUT(+) (pin5) using Kelvin connection, with a

value of:

Rtrim-up = 30.1 ∗ 󰇥󰇣VONOM∗(100+∆)

1.225∆󰇤−(100+2∆)

∆󰇦 [kΩ]

To trim the output voltage up, for example 24V to

26.4V, ∆=10 and required external resistor is:

Rtrim-up = 30.1 ∗ 󰇥󰇣∗()

.∗ 󰇤 − (∗)

 󰇦 = 6125 kΩ

Note that trimming output voltage more than 10% is

not recommended and OVP may be tripped.

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 MXW 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 MXW 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

MXW converter is thermally attached to a cold plate

inside chassis without any forced internal air

circulation; 2) the MXW 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 MXW 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 MXW 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 MXW converters. Exceeding

these specifications may cause damage to the MXW

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

MXW converters are not recommended for water

wash process. Contact the factory for additional

information if water wash is necessary.

2401 Stanwell Drive, Concord Ca. 94520,

Ph: 925-687-4411, Fax: 925-687-3333,

www.calex.com Email: sales@calex.com

Page 10 of 17

500 WATT MXW SERIES

DC/DC CONVERTER

ECO 171121-1, 181204-1

Test Configurations:

Fig. 2: Test setup for measuring input reflected ripple

currents iC and iS.

Fig. 3: Test setup for measuring output voltage ripple,

startup and step load transient waveforms.

2401 Stanwell Drive, Concord Ca. 94520,

Ph: 925-687-4411, Fax: 925-687-3333,

www.calex.com Email: sales@calex.com

Page 11 of 17

500 WATT MXW SERIES

DC/DC CONVERTER

ECO 171121-1, 181204-1

Characteristic Curves – Efficiency and Power Dissipation

Fig. 4: 24S12.41MXW (ROHS) Efficiency Curve

Fig. 6: 24S24.21MXW (ROHS) Efficiency Curve

Fig. 8: 24S28.18MXW (ROHS) Efficiency Curve

Fig. 5: 24S12.41MXW (ROHS) Power Dissipation

Fig. 7: 24S24.21MXW (ROHS) Power Dissipation

Fig. 9: 24S28.18MXW (ROHS) Power Dissipation

2401 Stanwell Drive, Concord Ca. 94520,

Ph: 925-687-4411, Fax: 925-687-3333,

www.calex.com Email: sales@calex.com

Page 12 of 17

500 WATT MXW SERIES

DC/DC CONVERTER

ECO 171121-1, 181204-1

Characteristic Curves – Derating Curves

Fig. 10: 24S12.41MXW (ROHS) Derating Curve

Fig. 12: 24S24.21MXW (ROHS) Derating Curve

Fig. 14: 24S28.18MXW (ROHS) Derating Curve

Fig. 11: 24S12.41MXW (ROHS) Derating Curve

Fig. 13: 24S24.21MXW (ROHS) Derating Curve

Fig. 15: 24S28.18MXW (ROHS) Derating Curve

0

50

100

150

200

250

300

350

400

450

500

550

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 -24S12.41MXW

Vin=9V Vin=12V Vin=24V-36V

0

50

100

150

200

250

300

350

400

450

500

550

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 -24S24.21MXW

Vin=9V Vin=12V Vin=24V-36V

0

50

100

150

200

250

300

350

400

450

500

550

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 - 24S28.18MXW

Vin=9V Vin=12V Vin=24V-36V

0

5

10

15

20

25

30

35

40

45

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 - 24S12.41MXW

Vin=9V Vin=12V Vin=24V - 36V

0

3

6

9

12

15

18

21

24

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 -24S24.21MXW

Vin=9V Vin=12V Vin=24V - 36V

0

3

6

9

12

15

18

21

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 - 24S28.18MXW

Vin=9V Vin=12V Vin=24V - 36V

2401 Stanwell Drive, Concord Ca. 94520,

Ph: 925-687-4411, Fax: 925-687-3333,

www.calex.com Email: sales@calex.com

Page 13 of 17

500 WATT MXW SERIES

DC/DC CONVERTER

ECO 171121-1, 181204-1

Characteristic Waveforms – 24S12.41MXW (ROHS)

Fig. 16: Turn-on by ON/OFF transient (with VIN applied) at full rated load

current (resistive) at VIN = 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% (20.5A – 31.5A – 20.5A) with di/dt = 1A/µs at VIN = 24V. Top

trace (C4): Output voltage (200 mV/div.). Bottom trace (C3): Load

current (20A/div.). CO 470µF/70mΩ. Time: 1ms/div.

Fig. 20: Output voltage ripple (100mv/div.) at full rated load current into

a resistive load at VIN = 24V. CO 470µF/70mΩ. Time: 2µs/div.

Fig. 17: Turn-on by VIN (ON/OFF high) transient at full rated load

current (resistive) at VIN = 24V. Top trace (C2): Input voltage VIN (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% (20.5A – 41A – 20.5A) with di/dt = 1A/µs at VIN = 24V. Top

trace (C4): Output voltage (500 mV/div.). Bottom trace (C3): Load

current (20A/div.). CO 470µF/70mΩ. Time: 1ms/div.

Fig. 21: Input reflected ripple current, iC (500 mA/mV), measured at

input terminals at full rated load current at VIN = 24V. Refer to Fig. 2 for

test setup. Time: 2 µs/div. RMS input ripple current is 1.235*500mA =

617.5mA.

2401 Stanwell Drive, Concord Ca. 94520,

Ph: 925-687-4411, Fax: 925-687-3333,

www.calex.com Email: sales@calex.com

Page 14 of 17

500 WATT MXW SERIES

DC/DC CONVERTER

ECO 171121-1, 181204-1

Characteristic Waveforms – 24S24.21MXW (ROHS)

Fig. 22: Turn-on by ON/OFF transient (with VIN applied) at full rated load

current (resistive) at VIN = 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% (10.5A – 15.75A – 10.5A) with di/dt = 1A/µs at VIN = 24V.

Top trace (C4): Output voltage (200 mV/div.). Bottom trace (C3): Load

current (10A/div.). CO 470µF/70mΩ. Time: 1ms/div.

Fig. 26: Output voltage ripple (200mv/div.) at full rated load current into

a resistive load at VIN = 24V. CO 470µF/70mΩ. Time: 2µs/div.

Fig. 23: Turn-on by VIN transient (ON/OFF high) at full rated load current

(resistive) at VIN = 24V. Top trace (C2): Input voltage VIN (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% (10.5A – 21A – 10.5A) with di/dt = 1A/µs at VIN = 24V. Top

trace (C4): Output voltage (500 mV/div.). Bottom trace (C3): Load

current (10A/div.). CO 470µF/70mΩ. Time: 1ms/div.

Fig. 27: Input reflected ripple current, iC (500 mA/mV), measured at

input terminals at full rated load current at VIN = 24V. Refer to Fig. 2 for

test setup. Time: 2 µs/div. RMS input ripple current is 1.359*500mA =

679.5mA.

2401 Stanwell Drive, Concord Ca. 94520,

Ph: 925-687-4411, Fax: 925-687-3333,

www.calex.com Email: sales@calex.com

Page 15 of 17

500 WATT MXW SERIES

DC/DC CONVERTER

ECO 171121-1, 181204-1

Characteristic Waveforms – 24S28.18MXW (ROHS)

Fig. 28: Turn-on by ON/OFF transient (with VIN applied) at full rated load

current (resistive) at VIN = 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% (9A – 13.5A – 9A) with di/dt = 1A/µs at VIN = 24V. Top trace

(C4): Output voltage (200 mV/div.). Bottom trace (C3): Load current

(10A/div.). CO 470µF/70mΩ. Time: 1ms/div.

Fig. 32: Output voltage ripple (200mv/div.) at full rated load current into

a resistive load at VIN = 24V. CO 470µF/70mΩ. Time: 2µs/div.

Fig. 29: Turn-on by VIN transient (ON/OFF high) at full rated load current

(resistive) at VIN = 24V. Top trace (C2): Input voltage VIN (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% (9A – 18A – 9A) with di/dt = 1A/µs at VIN = 24V. Top trace

(C4): Output voltage (500 mV/div.). Bottom trace (C3): Load current

(10A/div.). CO 470µF/70mΩ. Time: 1ms/div.

Fig. 33: Input reflected ripple current, iC (500 mA/mV), measured at

input terminals at full rated load current at VIN = 24V. Refer to Fig. 2 for

test setup. Time: 2 µs/div. RMS input ripple current is 1.098*500mA =

549mA.

2401 Stanwell Drive, Concord Ca. 94520,

Ph: 925-687-4411, Fax: 925-687-3333,

www.calex.com Email: sales@calex.com

Page 16 of 17

500 WATT MXW SERIES

DC/DC CONVERTER

ECO 171121-1, 181204-1

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 figure 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, Llkg = 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. CIN = 2 x 470µF/50V/70mΩ.

b) With input filter from Fig. 34.

Fig. 35: Input conducted emissions measurement (Typ.) of 24S24.21MXW (ROHS)

2401 Stanwell Drive, Concord Ca. 94520,

Ph: 925-687-4411, Fax: 925-687-3333,

www.calex.com Email: sales@calex.com

Page 17 of 17

500 WATT MXW SERIES

DC/DC CONVERTER

ECO 171121-1, 181204-1

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 MXW 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.