Hi-Rel DC/DC CONVERTER
MGDM-26 : 25W POWER
• 28Vdc input compliant with MIL-STD-704 D/E
• Nominal power up to 25 W
• Wide temperature range : -40°C/+105°C case
• High efficiency (typ. 83%)
• Soft start
• Galvanic isolation 1.500 VDC
• Synchronizable, load sharing and N+1 redundancy
• Integrated LC EMI filter
• No load to full load operation
• Permanent short circuit protection
• No optocoupler for high reliability
• RoHS or Leaded process option
Gaia Converter FC99-041.01/10 Revision I
©
REDEFINING THE SOURCE OF POWER
1-General
Single Output
Metallic Case - 1.500 VDC Isolation
Hi-Rel
Grade
For locations, phone, fax, E-Mail see back cover
The MGDM-26 series is a complete line of DC/DC
power modules designed for aerospace, military
and high-end industrial applications. These mo-
dules use a high frequency fixed swiching technic
at 1MHz providing excellent reliability, low noise
characteristics and high power density. Standard
models are available with standard input voltage
range of 9-36 or 16-40 volts. The series include
single output voltage choices of 3,3, 5, 12, 15
volts.
The MGDM-26 series include synchronization and
load sharing functions.
The synchronization function allows to synchronize
more than one converter to one frequency or an
external source frequency. The load sharing allows
parallel operation to increase power with a true
N+1 redundancy.
All the modules are designed with LC network
4
filters to minimize reflected input current ripple
and output voltage ripple.
The modules include a soft-start, an input
undervoltage lock-out and a permanent short
circuit protection to ensure efficient module pro-
tections. The soft-start allows current limitation
and eliminates inrush current during start-up.
The short circuit protection completely protects
the modules against short-circuits of any duration
by a shut-down and restores to normal when
the overload is removed.
The design has been carried out with surface
mount components and is manufactured in a
fully automated process to guarantee high
quality. The modules are potted with a bi-
component thermal conductive compound and
package in a metallic case to ensure the module’s
integrity under high environmental conditions.
2-Product Selection
Input Voltage Range
B : 3.3 VDC
C : 5 VDC
E : 12 VDC
F : 15 VDC
Output
Options : Suffix :
/T : option for -55°C start up operating temperature nothing : RoHS process
/S : option for screening and serialization -L : leaded process (available in N. America)
Permanent
H : 9-36 VDC
J : 16-40 VDC
* Consult factory
Transient
40 VDC/100 ms *
50 VDC/100 ms *
Single output model : MGDS - 26 - input output option suffix
/
For locations, phone, fax, E-Mail see back cover
2
Hi-Rel
Grade
MGDM-26 Series
Gaia Converter FC99-041.01/10 Revision I
©
4
2- Product Selection (continued)
Current
6 A
5 A
2,08 A
1,65 A
6 A
5 A
2.08 A
1,65 A
Reference
MGDS-26-H-B
MGDS-26-H-C
MGDS-26-H-E
MGDS-26-H-F
MGDS-26-J-B
MGDS-26-J-C
MGDS-26-J-E
MGDS-26-J-F
Output
3,3 VDC
5 VDC
12 VDC
15 VDC
3,3 VDC
5 VDC
12 VDC
15 VDC
Input range
9-36 VDC
9-36 VDC
9-36 VDC
9-36 VDC
16-40 VDC
16-40 VDC
16-40 VDC
16-40 VDC
Options
/T , /S
/T , /S
/T , /S
/T , /S
/T , /S
/T , /S
/T , /S
/T , /S
Converter Selection Chart
MGDS - 26 - J - C / T - L
Number of Outputs :
S : single output
Input voltage range :
H : 9-36 VDC
J : 16-40 VDC
Output voltage :
See table page 1
Option :
/T : -55°C start up operation
/S : screening & serialization
(consult application note
«screening grades»)
Suffix :
nothing : RoHS process
-L : Leaded process
(available in N. America)
Suffix
-, -L
-, -L
-, -L
-, -L
-, -L
-, -L
-, -L
-, -L
For locations, phone, fax, E-Mail see back cover
3
Hi-Rel
Grade
MGDM-26 Series
Gaia Converter FC99-041.01/10 Revision I
©
4
3- Electrical Specifications
Data are valid at +25°C, unless otherwise specified.
Note * : For 9-36V input range, the current is derated of 80% at 9V and increases linearly to full current at 12V.
Parameter Conditions Limit or
typical Units Single Output MGDS-26
26 - H 26 - J
Input
Nominal input voltage Full temperature range Nominal VDC 20 28
Permanent input
voltage range (Ui) Full temperature range Min. - Max. VDC 9-36 16-40
Transient input voltage Full load (Consult factory) Maximum VDC/S 40/0,1 50/0,1
Undervoltage lock-out
(UVLO)
Turn-on voltage
Turn-off voltage
Nominal
Nominal
VDC
VDC
8,5
7,5
15,5
14,5
Start up time
Ui nominal
Nominal output
Full load : resistive
Maximum ms 30 30
Reflected ripple current Ui nominal, full load at
switching freq. BW = 20MHz Maximum mApp 50 50
Input current in short
circuit mode (Average)
Ui nominal
Short-circuit Maximum mA 35 35
No load input current Ui nominal
No load Maximum mA 35 35
Input current in inhibit
mode
Ui nominal
Inhibit Maximum mA 25 25
Output
Output voltage
Full temperature range
Ui min. to max.
75% load
Nominal
Nominal
Nominal
Nominal
VDC
VDC
VDC
VDC
3,3
5
12
15
3,3
5
12
15
Set Point accuracy Ambient temperature : 25°c
Ui nominal, 75% load Maximum % +/- 2 +/- 2
Output power Full temperature range
Ui min. to max. Maximum W 25 25
Output current *
3,3V output
5V output
12V output
15V output
Full temperature range
Ui min. to max.
Maximum
Maximum
Maximum
Maximum
A
A
A
A
6
5
2,1
1,65
6
5
2,1
1,65
Ripple output voltage
3,3V and 5V output
12V output
15V output
Ui nominal
Full load
BW = 20MHz
Maximum
Maximum
Maximum
mVpp
mVpp
mVpp
50
50
60
50
50
60
Line regulation Ui min. to max.
Full load Maximum % +/- 1 +/- 1
Load regulation Ui nominal
No load to full load Maximum % +/- 2 +/- 2
Output Voltage Trim As function of output
voltage
Minimum
Maximum
%
%
- 20
+ 10
- 20
+ 10
Efficiency Ui nominal
Full load Typical % See on page 4
Maximum admissible
Capacity load
3,3V output
5V output
12V output
15V output
Full input voltage range
Full load
Per output
Maximum
Maximum
Maximum
Maximum
µF
µF
µF
µF
4.700
1.000
330
250
4.700
1.000
330
250
For locations, phone, fax, E-Mail see back cover
4
Hi-Rel
Grade
MGDM-26 Series
Gaia Converter FC99-041.01/10 Revision I
©
4
3- Electrical Characteristics (continued)
Figure 1 : Typical efficiency versus load
at various input
Efficiency (%)
5 10 20 25
Output Power (W) (MGDS-26-H-C module)
86
82
78
74
70
66
input 36V
input 20V
input 9V
Figure 2 : Typical efficiency versus load
at various input
Efficiency (%)
85
82
79
76
73
70
5 10 20 25
Output Power (W) (MGDS-26-H-E module)
input 36V
input 20V
input 9V
Figure 3 : Typical efficiency versus load
at various input
Efficiency (%)
6.25 12.5 18.75 25
Output Power (W) (MGDS-26-J-B module)
input 16V
input 28V
input 40V
80
71
74
77
83
Figure 4 : Typical efficiency versus load
at various input
Efficiency (%)
86
84
82
80
78
76
6.25 12.5 18.75 25
Output Power (W) (MGDS-26-J-C module)
input 16V
input 40V
input 28V
6.25 12.5 18.75 25
Output Power (W) (MGDS-26-J-E module)
Figure 5 : Typical efficiency versus load
at various input
Efficiency (%)
88
86
84
82
80
78
76
input 16V
input 40V
input 28V
6.25 12.5 18.75 25
Output Power (W) (MGDS-26-J-F module)
Figure 6 : Typical efficiency versus load
at various input
Efficiency (%)
88
86
84
82
80
78
76
input 16V
input 40V
input 28V
Figure 7 : Typical load regulation
characteristics at nominal input
Output Voltage (VDC)
3,45
3,40
3,35
3,30
3,25
3,20
0 8,5 16,5 25
Output Power (W) (MGDS-26-J-B module)
input 28V
Figure 8 : Typical load regulation
characteristics at nominal input
Output Voltage (VDC)
5,15
5,10
5,05
5,00
4,95
4,90
0 8,5 16,5 25
Output Power (W) (MGDS-26-J-C module)
input 28V
For locations, phone, fax, E-Mail see back cover
5
Hi-Rel
Grade
MGDM-26 Series
Gaia Converter FC99-041.01/10 Revision I
©
4
4- Switching Frequency
6- Protection Functions
Characteristics Protection Device Recovery Limit or typical Specifications
Input undervoltage lock-out (UVLO) Turn-on, turn-off circuit
with hysteresis cycle
Automatic
recovery
Turn-on nominal
Turn-off nominal See section 3
Output short circuit protection (SCP) Hiccup circuitry with
auto-recovery
Automatic
recovery Permanent See section 11
7- Reliability Data
Parameter Conditions Limit or typical Specifications
Switching frequency
Full temperature range
Ui min. to max.
No load to full load
Nominal, fixed 1 MHz
5- Isolation
Characteristics Conditions Temperature Specifications
Mean Time Between Failure (MTBF)
According to MIL-HDBK-217F
Ground fixed (Gf) Case at 40°C
Case at 85°C
750.000 Hrs
300.000 Hrs
Airborne, Inhabited,
Cargo (AIC)
Case at 40°C
Case at 85°C
410.000 Hrs
185.000 Hrs
Mean Time Between Failure (MTBF)
According to IEC-62380-TR Avionics Military Cargo / Consult factory
Parameter Conditions Limit or typical Specifications
Electric strength test voltage
Input to output
Input to case
Output to case
Minimum
Minimum
Minimum
1.500 VDC / 1 min
500 VDC / 1 min
1.500 VDC / 1 min
Isolation resistance 500 VDC Minimum 100 MOhm
For locations, phone, fax, E-Mail see back cover
6
Hi-Rel
Grade
MGDM-26 Series
Gaia Converter FC99-041.01/10 Revision I
©
4
8-1 Module Compliance with MIL-STD-461C/D/E Standards
8- Electromagnetic Interference
Electromagnetic Interference requirements according to MIL-STD-461C/D/E standards can be easily achieved as indicated in
the following section. The following table resumes the different sections covered by these standards.
To meet the latest US military standards MIL-STD-461D/E (and also the MIL-STD-461C) requirements and in particular the
conducted noise emission CE102 (and also CE03) requirements, Gaïa Converter can propose a stand-alone ready-to-use EMI
filter module. This EMI filter module has to be used together with a common mode noise capacitance Cc (10nF/rated voltage
depending on isolation requirement) connected between Gin and Gout.
EMI Filter module reference : FGDS-2A-50V.
Please consult EMI filter datasheet for further details.
Standard Requirements MIL-STD-461C
Standard
MIL-STD-461D/E
Standard
Compliance with GAIA Converter
Module & common mode capacitance
Conducted emission (CE) :
Low frequency
High frequency
CE 01
CE 03
CE 101
CE 102
compliant module stand-alone
compliant with additionnal filter
Conducted susceptibility (CS) :
Low frequency
High frequency
CS 01
CS 02
CS 101
CS114
compliant with additionnal filter
compliant with additionnal filter
Radiated emission (RE) :
Magnetic field
Electrical field
RE 01
RE 02
RE 101
RE 102
compliant module stand-alone
compliant module stand-alone
Radiated susceptibility (RS) :
Magnetic field
Electrical field
RS 01
RS 03
RS 101
RS 103
compliant module stand-alone
compliant module stand-alone
MGDM-series
Go
Vo
GI
VI
Cc
EMI input Filter
Go
Vo
GI
VI
For locations, phone, fax, E-Mail see back cover
7
Hi-Rel
Grade
MGDM-26 Series
Gaia Converter FC99-041.01/10 Revision I
©
4
9- Thermal Characteristics
Characteristics Conditions Limit or typical Performances
Operating ambient temperature
range at full load Ambient temperature * Minimum
Maximum
- 40°C
+ 85°C
Operating case temperature
range at full load Case temperature Minimum
Maximum
- 40°C
+ 105°C
Storage temperature range Non functionning Minimum
Maximum
- 55°C
+ 125°C
Thermal resistance Rth case to ambient in free air
natural convection Typical 7°C /W
Note * : The upper temperature range depends on configuration, the user must assure a max. case temperature of + 105°C.
10 10030 110807060 9020 40 50
25%
75%
50%
100%
Power (W)
Temperature (˚C)
Full load ambient temperature without derating : 85˚C
Maximum case temperature : 105˚C
Natural convection operation area
Additionnal cooling operation area
Maximum storage temperature : 125˚C
The MGDM-26 series operating case temperature must not exceed 105°C. The maximum ambient temperature admissible
for the DC/DC converter corresponding to the maximum operating case temperature of 105°C depends on the ambient
airflow, the mounting/orientation, the cooling features and the power dissipated.
To calculate a maximum admissible ambient temperature the following method can be used. Knowing the maximum case
temparature Tcase = 105°C of the module, the power used Pout and the efficiency η :
• determine the power dissipated by the module Pdiss that should be evacuated :
Pdiss = Pout(1/ηη
ηη
η - 1)
• determine the maximum ambient temperature :
Ta = 105°C - Rth x Pdiss
where Rth is the thermal resistance from the case to ambient.
The previous thermal calculation shows two areas of operation :
• a normal operation area in a free natural ambient convection (grey area in this following graph),
• an area with cooling features (air flow or heatsink) ensuring a maximum case temperature below the maximum
operating case temperature of 105°C (white area in the following graph).
For locations, phone, fax, E-Mail see back cover
8
Hi-Rel
Grade
MGDM-26 Series
Gaia Converter FC99-041.01/10 Revision I
©
4
10- Environmental Qualifications
The modules have been subjected to the following environmental qualifications.
Characteristics Conditions Severity Test procedure
Climatic Qualifications
Life at high
temperature
Duration
Temperature / status of unit
Test D : 1.000 Hrs
@ 105°C case, unit operating
@ 125°C ambient, unit not operating
MIL-STD-202G
Method 108A
Altitude
Altitude level C
Duration
Climb up
Stabilization
Status of unit
40.000 ft@-55°C
30 min.
1.000 ft/min to 70.000 f@-55°C,
30 min.
unit operating
MIL-STD-810E
Method 500.3
Humidity cyclic
Number of cycle
Cycle duration
Relative humidity variation
Temperature variation
Status of unit
10
Cycle I : 24 Hrs
60 % to 88 %
31°C to 41°C
unit not operating
MIL-STD-810E
Method 507.3
Humidity steady
Damp heat
Temperature
Duration
Status of unit
93 % relative humidity
40°C
56 days
unit not operating
MIL-STD-202G
Method 103B
Salt atmosphere
Temperature
Concentration NaCl
Duration
Status of unit
35°C
5 %
48 Hrs
unit not operating
MIL-STD-810E
Method 509.3
Temperature
cycling
Number of cycles
Temperature change
Transfert time
Steady state time
Status of unit
200
-40°C / +85°C
40 min.
20 min.
unit operating
MIL-STD-202A
Method 102A
Temperature shock
Number of shocks
Temperature change
Transfert time
Steady state time
Status of unit
100
-55°C / +105°C
10 sec.
20 min.
unit not operating
MIL-STD-202G
Method 107G
Mechanical Qualifications
Vibration
(Sinusoidal)
Number of cycles
Frequency / amplitude
Frequency / acceleration
Duration
Status of unit
10 cycles in each axis
10 to 60 Hz / 0.7 mm
60 to 2000 Hz / 10 g
2h 30 min. per axis
unit not operating
MIL-STD-810D
Method 514.3
Shock
(Half sinus)
Number of shocks
Peak acceleration
Duration
Shock form
Status of unit
3 shocks in each axis
100 g
6 ms
1/2 sinusoidal
unit not operating
MIL-STD-810D
Method 516.3
Bump
(Half sinus)
Number of bumps
Peak acceleration
Duration
Status of unit
2000 bumps in each axis
40 g
6 ms
unit not operating
MIL-STD-810D
Method 516.3
For locations, phone, fax, E-Mail see back cover
9
Hi-Rel
Grade
MGDM-26 Series
Gaia Converter FC99-041.01/10 Revision I
©
4
11- Description of Protections
11-1 Input Undervoltage Lock-out (UVLO)
An input undervoltage protection will inhibit the module
when input voltage drops below the lock-out turn-off
threshold (see section 3 for value) and restores to normal
operation automatically when the input voltage rises the
lock-out turn-on threshold.
11-2 Output Short Circuit Protection (SCP)
The short circuit protection device protects the module
against short circuit of any duration and restores the mo-
dule to normal operation when the short circuit is removed.
It operates in «hiccup» mode by testing periodically if an
overload is applied (typically every 1s recovery time). The
overload detection threshold is typically 200% of maxi-
mum current with a detection time lower than 5ms.
Vin
On
Off
UVLO
UVLO
Turn-on
Turn-off
For locations, phone, fax, E-Mail see back cover
10
Hi-Rel
Grade
MGDM-26 Series
Gaia Converter FC99-041.01/10 Revision I
©
4
On/Off
MGDS26
S-GI
VI
+Vo
Case Go
Trim
S+
Cont
Share
1
0
4
3
2
5
6
7
8
9
MGDS26
S-GI
VI
+Vo
Case Go
Trim
S+
Cont
Share
1
0
4
3
2
5
6
7
8
9
12- Description of Functions
13-1 Trim Function
The primary output voltage Vo may be trimmed at -20%/
+10% via a single external trimpot or fixed resistor. The trimpot
should be connected as shown in figure hereafter. Value of
the trim resistance is given in the following table.
For other Vo1 Output value consult Factory
12-3 On/Off Function
The control pin 4 (On/Off) can be used for applications requiring
On/Off operation. This may be done with an open collector
transistor, a switch, a relay or an optocoupler. Several converters
may be disabled with a single switch by connecting all On/Off
pins together.
• The converter is disabled by pulling low the pin 4.
• No connection or high impedance on pin 4 enables the
converter.
By releasing the On/Off function, the converter will restart
within the start up time specifications given in table section 3.
For further details please consult ‘’Logic On/Off’’ application note.
12-4 Synchronization Function
The MGDM-26 series provide a bi-directionnal
synchronization function trough pin 4 (CONT)
to enable automatic synchronisation
between several converters. The converters
lock into the highest switching frequency if
more than one converter is used or on an
external clock for a frequency in the range
between 105% and 115% of the converter’s
free frequency.
12-2 Sense Function
If the load is separated from the output by any line lenght,
some of these performance characteristics will be degraded
at the load terminals by an amount proportional to the
impedance of the load leads. Sense connections enable to
compensate the line drop at a maximum of +/-10% of output
voltage. Connection is described in figure herein.
Vo P1 Value
3,3 V 4,7 KOhm
5 V 10 KOhm
12 V 12 KOhm
15 V 22 KOhm
GI
On/Off
Command
LoadP1
MGDS26
S-
GI
VI +Vo
Case
Go
Trim
S+
Cont
Share
1
0
4
3
2
5
6
7
8
9
Load
MGDS26
S-
GI
VI +Vo
Case
Go
Trim
S+
Cont
Share
1
0
4
3
2
5
6
7
8
9
For locations, phone, fax, E-Mail see back cover
11
Hi-Rel
Grade
MGDM-26 Series
Gaia Converter FC99-041.01/10 Revision I
©
4
13- Application Notes
13-1 Connection of Modules in Series
The output of single output units can be connected in
series without any precautions to provide higher output
voltage level.
Nevertheless, GAIA Converter recommends to protect each
individual output by a low power shottky diode rated with
the maximum current of the converter to avoid reverse
polarity at any output.
Reverse polarity may occur at start up if the output volta-
ges do not rise at the same time.
13-2 Connection of Modules in Parallel
The MGDM-26 series features parallel (load sharing)
operations to increase output power with a true N+1
redundancy. Up to 4 converters can be parallelized through
the “SHARE” pins as described in the following schematic
MGDS26
S-
GI
VI +Vo
Case
Go
Trim
S+
Cont
Share
1
0
4
3
2
5
6
7
8
9
MGDS26
S-
GI
VI +Vo
Case
Go
Trim
S+
Cont
Share
1
0
4
3
2
5
6
7
8
9
MGDS26
S-
GI
VI +Vo
Case
Go
Trim
S+
Cont
Share
1
0
4
3
2
5
6
7
8
9
MGDS26
S-
GI
VI +Vo
Case
Go
Trim
S+
Cont
Share
1
0
4
3
2
5
6
7
8
9
For locations, phone, fax, E-Mail see back cover
12
Hi-Rel
Grade
MGDM-26 Series
Gaia Converter FC99-041.01/10 Revision I
©
4
14- Dimensions
17- Connections
Dimension are given in mm (inches). Tolerance : +/- 0,2 mm (+/- 0.01 “) unless otherwise indicated.
Weight : 65 grams (2.3 Ozs) max.
5 6 7 8 9 
0 1 2 3 4 
Bottom view
51,1 
(2.00)
45,7
(1.8)
3,05
(0.12)
51,1
(2.00)
4 x mouting 
threaded holes M3
3,05
(0.12)
2,69
(0.106)
R2,4 (0.1)
10,5 
(0.41)
15,39 +/-0,4
(0.6 +/-0.015)
5,08
(0.2)
5,08
(0.2)
5,08
(0.2)
5,08
(0.2)
12,86 +/-0,4
(0.5)
5,08
(0.2)
5,08
(0.2)
5,08
(0.2)
5,08
(0.2)
0,5 (0.019)
Pin 3 : round pin O 0,83 mm (0.032") length : 4 mm
All other pins : square pin 0,91mm (0.036") length : 5,5 mm
5,5
(0.22)
+1,5/-1
+/-1
+1,5/-1
Pin Single Output
0 Share
1 + Input (Vi)
2 - Input (Gi)
3 Case
4 Control (Cont)
5 Sense + (S+)
6 + Output (Vo)
7 Trim (Trim)
8 - Output (Go)
9 Sense - (S-)
15- Materials
Case : Metallic black anodized coating.
Pins : Plated with pure matte tin over nickel underplate.
16- Product Marking
Upper face : Company logo, location of manufacturing.
Side face : Module reference : MGDx-26-»X»-»Y».
Date code : year and week of manufacturing, suffix, /option.
Information given in this datasheet is believed to be accurate and reliable. However, no responsibility is assumed for the consequence of its use nor for any infringement of patents or other rights of third parties which may result from its use.
These products are sold only according to GAIA Converter general conditions of sale, unless otherwise confirmed by writing. Specifications subject to change without notice.
Printed in France by GAIA Converter FC99-041.01/10 Revision I Graphisme : Philippe Clicq
Represented by :
For more detailed specifications and applications information, contact :
International Headquarters
GAÏA Converter - France
ZI de la Morandière
33185 LE HAILLAN - FRANCE
Tel. : + (33)-5-57-92-12-80
Fax : + (33)-5-57-92-12-89
North American Headquarters
GAÏA Converter Canada, Inc
4038 Le Corbusier Blvd
LAVAL, QUEBEC - CANADA H7L 5R2
Tel. : (514)-333-3169
Fax : (514)-333-4519