Hi-Rel DC/DC CONVERTER
MGDM-75 : 75W POWER
• Ultra wide input range 16-80 Vdc, 9-45 Vdc
• 28Vdc input compliant with MIL-STD-704A/D/F
• Industry standard quarter brick package
• Power up to 75 W
• Wide temperature range : -40/+105°C baseplate
• High efficiency (typ. 86%-90%)
• Soft start
• Galvanic isolation 1.500 VDC
• Integrated LC EMI filter
• Synchronizable
• Fully protected by independant security
• Under & overvoltage lock-out
• Overvoltage protection
• Current limitation protection
• Overtemperature protection
• No optocoupler for high reliability
• Leaded process
Gaia Converter FC03-032.01/10 Revision I
©
REDEFINING THE SOURCE OF POWER
1-General
5:1 Ultra Wide Input
Single Output
Metallic case - 1.500 VDC Isolation
Hi-Rel
Grade
For locations, phone, fax, E-Mail see back cover
2-Product Selection
Input Voltage Range
B : 3.3 VDC
C : 5 VDC
E : 12 VDC
F : 15 VDC
I : 24 VDC
J : 28 VDC
Permanent
H : 9-45 VDC
O : 16-80 VDC
Output
4
The MGDM-75 series is a complete line of high
density wide input range DC/DC power modules
designed for aerospace, military and high-end
industrial applications. These modules use a
patented fixed switching topology at 420 KHz
providing ultra wide input range, low noise
characteristics and high power density. Standard
models are available with ultra wide input vol-
tage range of 9-45, 16-80 volts. The series
include single output voltage choices of 3.3, 5,
12, 15, 24, 28 volts.
The MGDM-75 series include synchronization, trim
and sense functions.
The synchronization function allows to synchronize
more than one converter to one frequency or an
external source frequency.
All the modules are designed with LC network
filters to minimize reflected input current ripple
and output voltage ripple.
The modules have totally independant security
functions including input undervoltage lock-out,
output overvoltage protection, output current
limitation protection, and temperature protec-
tion. Additionnally a soft-start function allows
current limitation and eliminates inrush current
during start-up.
The design has been carried out with surface
mount components, planar transformer and is
manufactured in a fully automated process to
guarantee high quality. The modules are potted
with a bi-component thermal conductive
compound and used an insulated metallic subs-
trat to ensure optimum power dissipation under
harsh environmental conditions.
Options :
/T : option for -55°C start up operating temperature
/S : option for screening and serialization
MGDS - 75 - option
/
input output
For locations, phone, fax, E-Mail see back cover
2
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MGDM-75 Series
Gaia Converter FC03-032.01/10 Revision I
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4
2- Product Selection (continued)
Current
15 A
12,5 A
6,25 A
5 A
3,125 A
2,7 A
15 A
15 A
6,25 A
5 A
3,125 A
2,7 A
Reference
MGDS-75-H-B
MGDS-75-H-C
MGDS-75-H-E
MGDS-75-H-F
MGDS-75-H-I
MGDS-75-H-J
MGDS-75-O-B
MGDS-75-O-C
MGDS-75-O-E
MGDS-75-O-F
MGDS-75-O-I
MGDS-75-O-J
Output
3.3 VDC
5 VDC
12 VDC
15 VDC
24 VDC
28 VDC
3.3 VDC
5 VDC
12 VDC
15 VDC
24 VDC
28 VDC
Input range
9-45 VDC
9-45 VDC
9-45 VDC
9-45 VDC
9-45 VDC
9-45 VDC
16-80 VDC
16-80 VDC
16-80 VDC
16-80 VDC
16-80 VDC
16-80 VDC
Options
/T , /S
/T , /S
/T , /S
/T , /S
/T , /S
/T , /S
/T , /S
/T , /S
/T , /S
/T , /S
/T , /S
/T , /S
Converter Selection Chart
MGDS - 75 - O - E / T
Number of Outputs :
S : single output
Input voltage range :
H : 9-45 VDC
O : 16-80 VDC
Output voltage :
See table page 1
Option :
(/T) : -55°C start up
(/S) : screening & serialization
(consult application note
«screening grades»)
For locations, phone, fax, E-Mail see back cover
3
Hi-Rel
Grade
MGDM-75 Series
Gaia Converter FC03-032.01/10 Revision I
©
4
3- Block Diagram
The MGDM-75 DC/DC converter is based on a cons-
tant 420KHz pulse-width modulated forward topology
designed for ultra large input range.
The output voltage is monitored on the secondary
side avoiding the use of optocoupler to optimize
long-term reliability and provide good immunity
against radiations.
An auxilliary supply is implemented to feed
independently all security functions such as the input
undervoltage lock-out (UVLO), the output overload
protection (OCP), the ouput overvoltage protection
(OVP) and the thermal protection (OTP).
As this auxilliary power is independent from the main
power supply, the module features a wide trim
windows from 90% to 110% of the nominal output
voltage.
The main power transformer designed for more than
75W power is a multi-layer planar transformer which
allows 100% reproductibility for optimized module
efficiencies.
The controlled feedback regulation is located at the
secondary side allowing a high regulation bandwidth
and a very fast response to load changes.
UVLO
Thermal
Shutdown
OVP
LC output
filter
LC input
filter
Mosfet
Driver
Current
Sense
POWER STAGE
Auxilliary
supply Feed-back
function
Vin
On/Off
Sync
Vo
Trim
Isolation Barrier
Control circuit Sense
For locations, phone, fax, E-Mail see back cover
4
Hi-Rel
Grade
MGDM-75 Series
Gaia Converter FC03-032.01/10 Revision I
©
4
Note * : These performances are measured with the sense line connected..
Note ** : It is recommended to mount the converter on a heatsink for this test, see section 10-3 and 10-9 for further details.
Note *** : The ripple output voltage is the periodic AC component imposed on the output voltage, an aperiodic and random component (noise) has also to be considered.
This noise can be reduced by adding 4 external decoupling capacitors connected between inputs and case and between outputs and case. These capacitance should
be layed-out as close as possible from the converter. Please refer to page 8 for more details.
4- Electrical Specifications
Data are valid at +25°C, unless otherwise specified.
Parameter Conditions Limit or
typical Units Single Output MGDS-75
75 - H 75 - O
Input
Nominal input voltage Full temperature range Nominal VDC 24 28
Permanent input
voltage range (Ui) Full temperature range Min. - Max. VDC 9 - 45 16 - 80
Undervoltage lock-out (UVLO) Turn-on voltage Maximum VDC 10,5 16
Start up time
Ui nominal
Nominal output
Full load : resistive
Maximum ms 30 30
Reflected ripple current Ui nominal, full load
BW = 20MHz Maximum mApp 500 500
Input current in short circuit
mode (Average)
Ui nominal
Short-circuit Typical A 1 0,2
No load input current Ui nominal
No load Maximum mA 30 30
Input current in inhibit mode Ui nominal
Inhibit Maximum mA 10 10
Output
Output voltage * Ui min. to max.
Nominal
Nominal
Nominal
Nominal
Nominal
Nominal
VDC
VDC
VDC
VDC
VDC
VDC
3,3
5
12
15
24
28
3,3
5
12
15
24
28
Set Point accuracy * Ambient temperature : +25°c
Ui nominal, 75% load Maximum % +/- 2 +/- 2
Output power At 105°c baseplate
Ui min. to max. Maximum W 50 to 75 50 to 75
Output current
3,3V output
5V output
12V output
15V output
24V output
28V output
Full temperature range
Ui min. to max.
Maximum
Maximum
Maximum
Maximum
Maximum
Maximum
A
A
A
A
A
A
15
12,5
6,25
5
3,125
2,7
15
15
6,25
5
3,125
2,7
Ripple output voltage
3,3V and 5V output
12V output
15V output
24V and 28V output
Ui nominal
Full load
BW = 20MHz
Typical
Typical
Typical
Typical
mVpp
mVpp
mVpp
mVpp
50
100
150
250
50
100
150
250
Output regulation *
(Line + load + thermal)
Ui min. to max.
0% to full load Maximum % +/- 1 +/- 1
Output Voltage Trim As function of output voltage Minimum
Maximum
%
%
90 **
110
90 **
110
Efficiency Ui nominal
Full load Typical % Please consult factory
For locations, phone, fax, E-Mail see back cover
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MGDM-75 Series
Gaia Converter FC03-032.01/10 Revision I
©
4
5 10 15 20 25 30 35 40 45
58%
60%
63%
65%
68%
70%
73%
75%
78%
80%
83%
85%
88%
Typical efficiency MGDS75HJ at 25°C
15W
30W
45W
60W
75W
Input voltage Vin (Vdc)
5 10 15 20 25 30 35 40 45
73%
74%
75%
76%
77%
78%
79%
80%
81%
82%
83%
84%
85%
86%
87%
88%
89%
Typical efficiency MGDS75HF at 25°C
15W
30W
45W
60W
75W
Input voltage Vin (Vdc)
5 10 15 20 25 30 35 40 45
68%
70%
72%
74%
76%
78%
80%
82%
84%
86%
88%
Typical efficiency MGDS75HE at 25°C
15W
30W
45W
60W
75W
Input voltage Vin (Vdc)
5 10 15 20 25 30 35 40 45
60%
63%
65%
68%
70%
73%
75%
78%
80%
83%
Typical efficiency MGDS75HC at 25°C
15W
30W
45W
60W
75W
Input voltage Vin (Vdc)
5 10 15 20 25 30 35 40 45
60%
63%
65%
68%
70%
73%
75%
78%
80%
83%
Typical efficiency MGDS75HB at 25°C
10W
20W
30W
40W
50W
Input voltage Vin (Vdc)
4- Electrical Characteristics (continued)
5 10 15 20 25 30 35 40 45
60%
63%
65%
68%
70%
73%
75%
78%
80%
83%
85%
88%
90%
Typical efficiency MGDS75HI at 25°C
15W
30W
45W
60W
75W
Input voltage Vin (Vdc)
For locations, phone, fax, E-Mail see back cover
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Grade
MGDM-75 Series
Gaia Converter FC03-032.01/10 Revision I
©
4
10 20 30 40 50 60 70 80
68%
70%
73%
75%
78%
80%
83%
85%
88%
90%
Typical efficiency MGDS75OJ at 25°C
15W
30W
45W
60W
75W
Input voltage Vin (Vdc)
10 20 30 40 50 60 70 80
68%
70%
72%
74%
76%
78%
80%
82%
84%
86%
88%
Typical efficiency MGDS75OE at 25°C
15W
30W
45W
60W
75W
Input voltage Vin (Vdc)
10 20 30 40 50 60 70 80
71%
72%
73%
74%
75%
76%
77%
78%
79%
80%
81%
82%
83%
84%
85%
86%
Typical efficiency MGDS75OC at 25°C
15W
30W
45W
60W
75W
Input voltage Vin (Vdc)
4- Electrical Characteristics (continued)
10 20 30 40 50 60 70 80
60%
63%
65%
68%
70%
73%
75%
78%
80%
83%
85%
88%
90%
Typical efficiency MGDS75OI at 25°C
15W
30W
45W
60W
75W
Input voltage Vin (Vdc)
10 20 30 40 50 60 70 80
70%
71%
72%
73%
74%
75%
76%
77%
78%
79%
80%
81%
82%
83%
84%
Typical efficiency MGDS75OB at 25°C
10W
20W
30W
40W
50W
Input voltage Vin (Vdc)
10 20 30 40 50 60 70 80
70%
72%
74%
76%
78%
80%
82%
84%
86%
88%
90%
Typical efficiency MGDS75OF at 25°C
15W
30W
45W
60W
75W
Input voltage Vin (Vdc)
For locations, phone, fax, E-Mail see back cover
7
Hi-Rel
Grade
MGDM-75 Series
Gaia Converter FC03-032.01/10 Revision I
©
4
5- Switching Frequency
7- 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 4
Output current limitation protection
(OCP)
Straight line current
limitation
Automatic
recovery Nominal 110% of
output current
Output overvoltage protection (OVP) Overvoltage protection
device with latch-up
Automatic
recovery Nominal 120% of
output voltage
Over temperature protection (OTP) Thermal device with
hysteresis cycle
Automatic
recovery Nominal 115°C
8- Reliability Data
Parameter Conditions Limit or typical Specifications
Switching frequency
Full temperature range
Ui min. to max.
No load to full load
Nominal, fixed 420 KHz
6- 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
700.000 Hrs
190.000 Hrs
Airborne, Inhabited,
Cargo (AIC)
Case at 40°C
Case at 85°C
390.000 Hrs
125.000 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
1.500 VDC / 1 min
1.500 VDC / 1 min
Isolation resistance 500 VDC Minimum 100 MOhm
For locations, phone, fax, E-Mail see back cover
8
Hi-Rel
Grade
MGDM-75 Series
Gaia Converter FC03-032.01/10 Revision I
©
4
9- 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.
9-1 Module Compliance with MIL-STD-461C/D/E 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 4 external decoupling capacitance Cc (10nF/rated
voltage depending on isolation requirement) connected between input and case and output and case.
EMI Filter module reference : FGDS-20A-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
Applicability H, O input module H, O input module see EMI datasheet
Cc
Cc
Cc
Cc
BP
BP
MGDM-series
GI
VI Vo
Go
BP
BP
BP: Base Plate
EMI input Filter
Go
Vo
GI
VI
For locations, phone, fax, E-Mail see back cover
9
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MGDM-75 Series
Gaia Converter FC03-032.01/10 Revision I
©
4
10- Thermal Characteristics
Characteristics Conditions Limit or typical Performances
Operating ambient temperature range
at full load Ambient temperature * Minimum
Maximum
- 40°C
see section 10-9
Baseplate temperature Base plate temperature Minimum
Maximum
- 40°C
+ 105°C
Storage temperature range Non functionning Minimum
Maximum
- 55°C
+ 125°C
Thermal resistance Baseplate to ambient
Rth(b-a) free air Typical 11°C/W
Note * : The upper temperature range depends on configuration, the user must ensure a max. baseplate temperature of + 105°C.
The MGDM-75 series maximum baseplate temperature at
full load must not exceed 105°C. Heat can be removed
from the baseplate via three basic
mechanisms :
• Radiation transfert : radiation is counting for less
than 5% of total heat transfert in majority of case, for
this reason the presence of radient cooling is used as
a safety margin and is not considered.
• Conduction transfert : in most of the applications,
heat will be conducted from the baseplate into an
attached heatsink or heat conducting member; heat is
conducted thruthe interface.
• Convection transfert : convecting heat transfer
into air refers to still air or forced air cooling.
In majority of the applications, heat will be removed from
the baseplate either with :
• heatsink,
• forced air cooling,
• both heatsink and forced air cooling.
To calculate a maximum admissible ambient temperature
the following method can be used.
Knowing the maximum baseplate temparature Tbase =
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) (A)
• determine the maximum ambient temperature :
Ta = 105°C - Rth(b-a) x Pdiss (B)
where Rth(b-a) is the thermal resistance from the
baseplate to ambient.
This thermal Rth(b-a) resistance is the summ of :
• the thermal resistance of baseplate to heatsink
(Rth(b-h)). The interface between baseplate and
heatsink can be nothing or a conducting member, a
thermal compound, a thermal pad.... The value of
Rth(b-h) can range from 0.4°C/W for no interface down
to 0.1°C/W for a thermal conductive member inter-
face.
• the thermal resistance of heatsink to ambient air
(Rth(h-a)), which is depending of air flow and given
by heatsink supplier.
The table hereafter gives some example of thermal resistance for different heat transfert configurations.
Radian and Thermaflo are heasink manufacturers. «Silpad» © is a registered trademark of Bergquist.
Note* : Silpad performance are for Silpad 400 with pressure conditions of 50 Psi. Surface of MGDS-75 series is 3,3 inch2.
Heat transfert Thermal resistance heatsink to air Rth(h-a) Thermal resistance baseplate to
heatsink
Global
resistance
Free air cooling
only
No Heatsink baseplate only : 11°C/W No need of thermal pad 11°C/W
Heatsink Thermaflo 4245OOBOOOO : 7,64°C/W Bergquist Silpad* : 0,21°C/W 7,85°C/W
Heatsink Thermaflo 4248OOBOOOO : 3,5°C/W Bergquist Silpad* : 0,21°C/W 3,71°C/W
Forced air cooling
200 LFM
No Heatsink baseplate only : 6,9°C/W No need of thermal pad 6,9°C/W
Heatsink Radian HS1568EX : 3,5°C/W Bergquist Silpad* : 0,21°C/W 3,71°C/W
Heatsink Thermaflo 4248OOBOOOO : 2,8°C/W Bergquist Silpad* : 0,21°C/W 3,01°C/W
Forced air cooling
400 LFM
No Heatsink baseplate only : 4,8°C/W No need of thermal pad 4,8°C/W
Heatsink Radian HS1568EX : 2°C/W Bergquist Silpad* : 0,21°C/W 2,21°C/W
Heatsink Thermaflo 4248OOBOOOO : 1,8°C/W Bergquist Silpad* : 0,21°C/W 2,01°C/W
Forced air cooling
1000 LFM
No Heatsink baseplate only : 2,8°C/W No need of thermal pad 2,8°C/W
Heatsink Thermaflo 4248OOBOOOO : 1°C/W Bergquist Silpad* : 0,21°C/W 1,21°C/W
For locations, phone, fax, E-Mail see back cover
10
Hi-Rel
Grade
MGDM-75 Series
Gaia Converter FC03-032.01/10 Revision I
©
4
10- Thermal Characteristics (continued)
The two formulas (A) and (B) described in previous page :
• Pdiss = Pout(1/ηη
ηη
η - 1) (A)
• Ta = 105°C - Rth(b-a) x Pdiss (B)
conduct to curves determining the ambient temperature
admissible as a function of output power for various heat
transfert conditions.
In particular, as example the following typical curves are
calculated with :
• no heatsink
• a Thermaflo heatsink reference 424800B0000 and a
Bergquist «Silpad» for various cooling conditions.
0 10 20 30 40 50 60 70 80 90 100 110
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
MGDS-75-H-x Series Thermal Curves
no heatsink
no heatsink 200LFM
no heatsink 400 LFM
heatsink 1000 LFM
heatsink
heatsink 200 LFM
heatsink 400 LFM
heatsink 1000 LFM
Ambient temperature (°C)
Output power (W)
0 10 20 30 40 50 60 70 80 90 100 110
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
MGDS-75-O-x Series Thermal Curves
no heatsink
no heatsink 200LFM
no heatsink 400 LFM
heatsink 1000 LFM
heatsink
heatsink 200 LFM
heatsink 400 LFM
heatsink 1000 LFM
Ambient temperature (°C)
Output power (W)
For locations, phone, fax, E-Mail see back cover
11
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Gaia Converter FC03-032.01/10 Revision I
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4
11- 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
12
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Gaia Converter FC03-032.01/10 Revision I
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12- Description of Protections
12-2 Output Over Current Protection (OCP)
The MGDM-75 Series incorporates a staight line current limit
and protection circuit. When the output current reaches 110%
of it’s full-rated current (Icurrent limit), the output voltage
falls and output current falls along the vertical line as described
in the figure herein. The module restart automatically to nor-
mal operation when overcurrent is removed.
12-3 Output Overvoltage Protection (OVP)
Each circuit has an internal overvoltage protection circuit that
monitors the voltage accross the output power terminals.
It is designed to turn the converter off at 120%
(+/-5%) of output voltage.
Once in OVP protection, the module will restart automatically
when overvoltage is removed.
The MGDM-75 series include 3 types of protection devices that
are powered and controlled by a fully independant side power
stage.
12-4 Over Temperature Protection (OTP)
A thermal protection device adjusted at 115°C (+/-5%) internal
temperature with 10°C hysteresis cycle will inhibit the mo-
dule as long as the overheat is present and restores to nor-
mal operation automatically when overheat is removed. The
efficiency of the OTP function is warranty with the module
mounted on a heatsink.
Iout
Vout
Icurrent limit
110% of full
rated current
130% of full
rated current
Baseplate
Temperature
On
115˚c
Off
10˚c
12-1 Input Undervoltage Lockout (UVLO)
12-1-1 Undervoltage Lockout (UVLO)
An undervoltage protection will inhibit the module when input
voltage drops below the lockout turn-off threshold (see sec-
tion 4 for value) and restores to normal operation automatically
when the input voltage rises the lockout turn-on threshold.
Vin
On
Off
UVLO
Turn-on
1,5V
For locations, phone, fax, E-Mail see back cover
13
Hi-Rel
Grade
MGDM-75 Series
Gaia Converter FC03-032.01/10 Revision I
©
4
13- Description of Functions
13-1 Trim Function
The output voltage Vo may be trimmed in a range of
90%/110% of the nominal output voltage via a single external
trimpot or fixed resistor.
Trim Up Function
Do not attempt to trim the module higher than 110% of
nominal output voltage as the overvoltage protection may
occur.
Also do not exceed the maximum rated output power when
the module is trimmed up.
The trim up resistor must be connected to S+ pin.
The trim up resistance must be calculated with the following
formula :
Ru = R1 (V0-Vref)V0nom - R1 - R2
(V0-V0nom)Vref
Trim Down Function
Do not trim down more than -10% of nominal output vol-
tage.
The available output power is reduced by the same
percentage that output voltage is trimmed down.
The trim down resistor must be connected to S- pin.
The trim down resistance must be calculated with the
following formula :
Rd = (R2 + R1)V0- R2V0nom
V0nom - V0
Trim via a voltage
The output voltage is given by the following formula :
V0 = 1 + R1 (Vtrim - 1)
(R1 + R2) Vref
Parameter Unit Min. Typ. Max.
Trim reference Vdc 2,45 2,5 2,55
Resistor R1 Ohm / 3800 /
Resistor R2 Ohm / 270 /
Trim capacitor µF / 1 /
MGDM75
S-
Gin
Vin Vo
On/Off
Go
Trim
S+
Sync
4
2
3
1
5
6
7
9
8
Load
Ru
R1 R2
1µF
Vref=
2.5V
Error amp.
Vcontrol
100nF
BAT54
MGDM75
S-
Gin
Vin Vo
On/Off
Go
Trim
S+
Sync
4
2
3
1
5
6
7
9
8
Load
Rd
R1 R2
1µF
Vref=
2.5V
Error amp.
MGDM75
S-
Gin
Vin Vo
On/Off
Go
Trim
S+
Sync
4
2
3
1
5
6
7
9
8
Load
Ru
R1 R2
1µF
Vref=
2.5V
Error amp.
For locations, phone, fax, E-Mail see back cover
14
Hi-Rel
Grade
MGDM-75 Series
Gaia Converter FC03-032.01/10 Revision I
©
4
13- Description of Functions (continued)
13-3 On/Off Function
The control pin 3 (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 3.
• 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.
13-4 Synchronization Function
An external clock with rectangular «Pull Up» signals can be
used to lock one or more converters. The external clock si-
gnal should have a frequency range from 860KHz to 940KHz,
a low level below 0,5V a high level of 4V (+/-0.5V), a rise
time of 30 ns max. and a drop time of 100ns max..
Parameter Unit Min. Typ. Max. Notes, conditions
On/Off module enable voltage Vdc 2 / 4,5 Open, the switch must not sink more than 100µA
On/Off module disable voltage Vdc 0 / 0.5 The switch must be able to sink 1mA
On/Off module enable delay ms / / 30 The module restarts with the same delay after alarm mode removed
On/Off module disable delay µs / / 100 Vi nominal, full load
Vin
4V
+/- 0,5
T/2
Vsync
0V
100ns
max
30ns
max
T
( 860Khz < F < 940Khz )
13-2 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. The overvoltage protection will be activated and module
will shut down if remote sense tries to boost output voltage
above 110% of nominal output voltage. Connection is described
in figure herein.
MGDM75
S-
Gin
Vin Vo
On/Off
Go
Trim
S+
Sync
4
2
3
1
5
6
7
9
8
Load
BP
Load
Totem pole
output
Gi
Vi
100pF
1N4148 4.7k
Ext. clock MGDM75
S-
Gin
Vin Vo
On/Off
Go
Trim
S+
Sync
4
2
3
1
5
6
7
9
8
BP
Load
On/Off
Gi
Vi
MGDM75
S-
Gin
Vin Vo
On/Off
Go
Trim
S+
Sync
4
2
3
1
5
6
7
9
8
For locations, phone, fax, E-Mail see back cover
15
Hi-Rel
Grade
MGDM-75 Series
Gaia Converter FC03-032.01/10 Revision I
©
4
14- Application Notes
14-1 Synchronization of Modules
The MGDM-75 series provides a synchronization function
trough the pin 2 (Synchro) to enable automatic synchroni-
sation between several converters.
If several converters are used, they lock themselves into
the highest switching frequency.
The synchronization signal available on pin 2 is referenced
to ground in (Gi) and the signal shape is the double of the
switching frequency (i.e 2x420KHz). It is a rectangular
signal with 3.5 Vp (+/-0.5V) amplitude with an impedance
of 4,7 KOhm on low level.
14-2 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.
10nF
10nF
10nF
10nF
BP
BP
(*)
BP: Base Plate
10nF
10nF
10nF
10nF
100µF
BP
BP
(*)
100µF
MGDM75
S-
Gin
Vin Vo
On/Off
Go
Trim
S+
Sync
4
2
3
1
5
6
7
9
8
MGDM75
S-
Gin
Vin Vo
On/Off
Go
Trim
S+
Sync
4
2
3
1
5
6
7
9
8
10nF
10nF
10nF
10nF
BP
BP
(*)
BP: Base Plate
10nF
10nF
10nF
10nF
BP
BP
(*)
MGDM75
S-
Gin
Vin Vo
On/Off
Go
Trim
S+
Sync
4
2
3
1
5
6
7
9
8
MGDM75
S-
Gin
Vin Vo
On/Off
Go
Trim
S+
Sync
4
2
3
1
5
6
7
9
8
On/Off
For locations, phone, fax, E-Mail see back cover
16
Hi-Rel
Grade
MGDM-75 Series
Gaia Converter FC03-032.01/10 Revision I
©
4
11- Dimensions
Dimensions are given in mm (inches). Tolerance : +/- 0,2 mm (+/- 0.01 “) unless otherwise indicated.
Weight : 70 grams (1.95 Ozs) max.
14- Connections
Use this side
for heat sinking
5.6 min
(0,22)
6.8 max
(0,267)
12.7 Max
(0,5)
0.5 (0,019)
Mouting Hole
0 3,1 (0.122)
3,81 (0.15)
10,795
(0.425)
9,894
(0.39)
26,16 (1.03)
36,83 (1.45)
R2,4 (0.1)
CH 2x2
57,912 (2.28)
9,589
(0.38)
3,81 (0.15)
3,81 (0.15)
3,81 (0.15)
47,24 (1.86)
50,8 (2.00)
3,56 (0.14)
3,56 (0.14)
Pin dimensions :
Pins : 1, 2, 3, 4, 7, 8 : Ø 1 mm (0.04”)
Pins : 5, 9 : Ø 1,5 mm (0.059”)
2 431
8569 7
Bottom view
Pin Single Output
1 - Input (Gi)
2 Synchro (Sync)
3 On/Off
4 + Input (Vi)
5 + Output (Vo)
6 Sense + (S+)
7 Trim (Trim)
8 Sense - (S-)
9 - Output (Go)
12- Materials
Frame : Aluminium alodined coating.
Baseplate : Copper with tin finishing.
Pins : Plated with pure matte tin over nickel underplate.
13- Product Marking
Upper face : Company logo, location of manufacturing.
Side face : Module reference, option, date code : year and week of manufacturing.
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 FC03-032.01/10 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
