Doc.# 005-MQ2750S Rev. GProduct# MQFL-270-05S Phone 1-888-567-9596 www.SynQor.com 08/13/13
Page 1
MQFL-270-05S-Y-ES
270Vin 5.0Vout@24A
DC-DC CONVERTER
+VIN
IN RTN
CASE
ENA 1
SYNC OUT
SYNC IN
ENA 2
SHARE
+SNS
-SNS
OUT RTN
+VOUT
S/N 0000000 D/C 3205-301 CAGE 1WX10
HigH Reliability DC-DC ConveRteR
Full PoweR oPeRation: -55ºC to +125ºC
Features
MQFL series converters (with MQME filter) are designed to meet:
Specification Compliance
MQFL series converters are:
Design Process
MQFL series converters are qualified to:
Qualification Process
In-Line Manufacturing Process
DesigneD & ManufactureD in the usa
featuring Qorseal
™
hi-rel asseMbly
• Designed for reliability per NAVSO-P3641-A guidelines
• Designed with components derated per:
— MIL-HDBK-1547A
— NAVSO P-3641A
• MIL-STD-810F
— consistent with RTCA/D0-160E
• SynQor’s First Article Qualication
— consistent with MIL-STD-883F
• SynQor’s Long-Term Storage Survivability Qualication
• SynQor’s on-going life test
• AS9100 and ISO 9001:2008 certied facility
• Full component traceability
• Temperature cycling
• Constant acceleration
• 24, 96, 160 hour burn-in
• Three level temperature screening
• MIL-HDBK-704-7 (A through F)
• RTCA/DO-160 Section 16, 17, 18
• MIL-STD-1275 (B, D)
• DEF-STAN 61-5 (part 6)/(5, 6)
• MIL-STD-461 (C, D, E, F)
• RTCA/DO-160(E, F, G) Section 22
• Fixed switching frequency
• No opto-isolators
• Parallel operation with current share
• Remote sense
• Clock synchronization
• Primary and secondary referenced enable
• Continuous short circuit and overload protection
with auto-restart feature
• Input under-voltage and over-voltage shutdown
The MilQor@ series of high-reliability DC-DC converters
brings SynQor’s eld proven high-efciency synchronous
rectier technology to the Military/Aerospace industry.
SynQor’s innovative QorSealTM packaging approach ensures
survivability in the most hostile environments. Compatible
with the industry standard format, these converters operate
at a xed frequency, have no opto-isolators, and follow
conservative component derating guidelines. They are
designed and manufactured to comply with a wide range of
military standards.
MQFL-270-05S
Single Output
155-400 V 155-475 V 5.0 V 24 A 86% @ 12A / 88% @ 24A
Continuous Input Transient Input Output Output Efciency
Doc.# 005-MQ2750S Rev. GProduct# MQFL-270-05S Phone 1-888-567-9596 www.SynQor.com 08/13/13
Page 2
Technical Specification
MQFL-270-05S
Output: 5.0V
Current: 24A
BLOCK DIAGRAM
TYPICAL CONNECTION DIAGRAM
ISOLATION STAGE
REGULATION STAGE
UVLO
OVSD
CONTROL
POWER
PRIMARY
CONTROL
+Vin
INPUT
RETURN
CASE
ENABLE 1
SYNC OUT
SYNC IN
1
2
3
4
5
6
GATE DRIVERS
ISOLATION BARRIER
CURRENT
LIMIT
CURRENT
SENSE
BIAS POWER
TRANSFORMER
T1
T2
MAGNETIC
DATA COUPLING
7
8
SECONDARY
CONTROL
GATE DRIVERS
12
11
10
9
−
SENSE
+Vout
OUTPUT
RETURN
SHARE
ENABLE 2
+ SENSE
T1 T2
MQFL
+VIN
IN RTN
CASE
ENA 1
SYNC OUT
SYNC IN
ENA 2
SHARE
+SNS
-SNS
OUT RTN
+VOUT
1
2
3
4
5
6
12
11
10
9
8
7
Load
open
means
on
+
+
270 Vdc
open
means
on
__
__
Doc.# 005-MQ2750S Rev. GProduct# MQFL-270-05S Phone 1-888-567-9596 www.SynQor.com 08/13/13
Page 3
Technical Specification
MQFL-270-05S
Output: 5.0V
Current: 24A
MQFL-270-05S ELECTRICAL CHARACTERISTICS
Parameter Min. Typ. Max. Units Notes & Conditions Group A
Vin=270 V dc ±5%, Iout=24 A, CL=0 µF, free running (see Note 10) unless
otherwise specied Subgroup
(see Note 13)
ABSOLUTE MAXIMUM RATINGS
Input Voltage
Non-Operating 600 V
Operating 550 V See Note 1
Reverse Bias (Tcase = 125ºC) -0.8 V
Reverse Bias (Tcase = -55ºC) -1.2 V
Isolation Voltage (I/O to case, I to O)
Continuous -500 500 V
Transient (≤100 µs) -800 800 V
Operating Case Temperature -55 125 °C HB Grade Products, See Notes 2 & 16
Storage Case Temperature -65 135 °C
Lead Temperature (20 s) 300 °C
Voltage at ENA1, ENA2 -1.2 50 V
INPUT CHARACTERISTICS
Operating Input Voltage Range 155 270 400 V Continuous 1, 2, 3
“ 155 270 475 V Transient, 1 s 4, 5, 6
Input Under-Voltage Lockout See Note 3
Turn-On Voltage Threshold 142 150 155 V 1, 2, 3
Turn-Off Voltage Threshold 133 140 145 V 1, 2, 3
Lockout Voltage Hysteresis 5 11 17 V 1, 2, 3
Input Over-Voltage Shutdown See Note 3
Turn-Off Voltage Threshold 490 520 550 V 1, 2, 3
Turn-On Voltage Threshold 450 475 500 V 1, 2, 3
Shutdown Voltage Hysteresis 20 50 80 V 1, 2, 3
Maximum Input Current 1 A Vin = 155 V; Iout = 24 A 1, 2, 3
No Load Input Current (operating) 28 37 mA 1, 2, 3
Disabled Input Current (ENA1) 1 4 mA Vin = 155 V, 270 V, 475 V 1, 2, 3
Disabled Input Current (ENA2) 6 11 mA Vin = 155 V, 270 V, 475 V 1, 2, 3
Input Terminal Current Ripple (pk-pk) 140 180 mA Bandwidth = 100 kHz – 10 MHz; see Figure 14 1, 2, 3
OUTPUT CHARACTERISTICS
Output Voltage Set Point (Tcase = 25ºC) 4.95 5.00 5.05 V Vout at sense leads 1
Vout Set Point Over Temperature 4.92 5.00 5.08 V “ 2, 3
Output Voltage Line Regulation -20 0 20 mV “ ; Vin = 155 V, 270 V, 400 V; Iout=24 A 1, 2, 3
Output Voltage Load Regulation 15 25 35 mV “ ; Vout @ (Iout=0 A) - Vout @ (Iout=24 A) 1, 2, 3
Total Output Voltage Range 4.90 5.00 5.10 V “ 1, 2, 3
Vout Ripple and Noise Peak to Peak 20 50 mV Bandwidth = 10 MHz; CL=11µF 1, 2, 3
Operating Output Current Range 0 24 A 1, 2, 3
Operating Output Power Range 0 120 W 1, 2, 3
Output DC Current-Limit Inception 25 29 32 A See Note 4 1, 2, 3
Short Circuit Output Current 26 30 34 A Vout ≤ 1.2 V; see Note 15 1, 2, 3
Back-Drive Current Limit while Enabled 5.5 A 1, 2, 3
Back-Drive Current Limit while Disabled 10 75 mA 1, 2, 3
Maximum Output Capacitance 10,000 µF See Note 5
DYNAMIC CHARACTERISTICS
Output Voltage Deviation Load Transient See Note 6
For a Pos. Step Change in Load Current -575 -375 mV Total Iout step = 12A‹-›24A, 2.4A‹-›12A; CL=11µF 4, 5, 6
For a Neg. Step Change in Load Current 375 575 mV “ 4, 5, 6
Settling Time (either case) 200 500 µs See Note 7 4, 5, 6
Output Voltage Deviation Line Transient Vin step = 155V‹-›400V; CL=11 µF; see Note 8
For a Pos. Step Change in Line Voltage -500 500 mV “ 4, 5, 6
For a Neg. Step Change in Line Voltage -800 800 mV “ 4, 5, 6
Settling Time (either case) 500 600 µs Iout = 12 A; See Note 7 See Note 5
Turn-On Transient
Output Voltage Rise Time 6 10 ms Vout = 0.5V-›4.5V 4, 5, 6
Output Voltage Overshoot 0 2 % See Note 5
Turn-On Delay, Rising Vin 50 75 120 ms ENA1, ENA2 = 5 V; see Notes 9 & 11 4, 5, 6
Turn-On Delay, Rising ENA1 5 10 ms ENA2 = 5 V; see Note 11 4, 5, 6
Turn-On Delay, Rising ENA2 2 4 ms ENA1 = 5 V; see Note 11 4, 5, 6
EFFICIENCY
Iout = 24 A (155 Vin) 85 89 % 1, 2, 3
Iout = 12 A (155 Vin) 86 89 % 1, 2, 3
Iout = 24 A (270 Vin) 84 88 % 1, 2, 3
Iout = 12 A (270 Vin) 82 86 % 1, 2, 3
Iout = 24 A (400 Vin) 81 85 % 1, 2, 3
Iout = 12 A (400 Vin) 77 82 % 1, 2, 3
Load Fault Power Dissipation 19 29 W Iout at current limit inception point; See Note 4 1, 2, 3
Short Circuit Power Dissipation 24 34 W Vout ≤ 1.2 V 1, 2, 3
Doc.# 005-MQ2750S Rev. GProduct# MQFL-270-05S Phone 1-888-567-9596 www.SynQor.com 08/13/13
Page 4
Technical Specification
MQFL-270-05S
Output: 5.0V
Current: 24A
MQFL-270-05S ELECTRICAL CHARACTERISTICS (Continued)
Parameter Min. Typ. Max. Units Notes & Conditions Group A
Vin=270 V dc ±5%, Iout=24 A, CL=0 µF, free running (see Note 10) unless
otherwise specied Subgroup
(see Note 13)
ISOLATION CHARACTERISTICS
Isolation Voltage Dielectric strength
Input RTN to Output RTN 500 V 1
Any Input Pin to Case 500 V 1
Any Output Pin to Case 500 V 1
Isolation Resistance (in rtn to out rtn) 100 MΩ 1
Isolation Resistance (any pin to case) 100 MΩ 1
Isolation Capacitance (in rtn to out rtn) 44 nF 1
FEATURE CHARACTERISTICS
Switching Frequency (free running) 500 550 600 kHz 1, 2, 3
Synchronization Input
Frequency Range 500 700 kHz 1, 2, 3
Logic Level High 2.0 5.5 V 1, 2, 3
Logic Level Low -0.5 0.8 V 1, 2, 3
Duty Cycle 20 80 % See Note 5
Synchronization Output
Pull Down Current 20 mA VSYNC OUT = 0.8 V See Note 5
Duty Cycle 25 75 % Output connected to SYNC IN of other MQFL unit See Note 5
Enable Control (ENA1 and ENA2)
Off-State Voltage 0.8 V 1, 2, 3
Module Off Pulldown Current 80 µA Current drain required to ensure module is off See Note 5
On-State Voltage 2 V 1, 2, 3
Module On Pin Leakage Current 20 µA Imax draw from pin allowed with module still on See Note 5
Pull-Up Voltage 3.2 4.0 4.8 V See Figure A 1, 2, 3
RELIABILITY CHARACTERISTICS
Calculated MTBF (MIL-STD-217F2)
GB @ Tcase = 70ºC 2600 103 Hrs.
AIF @ Tcase = 70ºC 300 103 Hrs.
WEIGHT CHARACTERISTICS
Device Weight 79 g
Electrical Characteristics Notes
1. Converter will undergo input over-voltage shutdown.
2. Derate output power to 50% of rated power at Tcase = 135ºC. 135ºC is above specied operating range.
3. High or low state of input voltage must persist for about 200µs to be acted on by the lockout or shutdown circuitry.
4. Current limit inception is dened as the point where the output voltage has dropped to 90% of its nominal value.
5. Parameter not tested but guaranteed to the limit specied.
6. Load current transition time ≥ 10 µs.
7. Settling time measured from start of transient to the point where the output voltage has returned to ±1% of its nal value.
8. Line voltage transition time ≥ 250 µs.
9. Input voltage rise time e 250 µs.
10. Operating the converter at a synchronization frequency above the free running frequency will slightly reduce the converter’s efciency and may also cause
a slight reduction in the maximum output current/power available. For more information consult the factory.
11. After a disable or fault event, module is inhibited from restarting for 300 ms. See Shut Down section.
12. SHARE pin outputs a power failure warning pulse during a fault condition. See Current Share section.
13. Only the ES and HB grade products are tested at three temperatures. The C- grade products are tested at one temperature. Please refer to the ESS table
for details.
14. These derating curves apply for the ES and HB grade products. The C- grade product has a maximum case temperature of 70ºC and a maximum junction
temperature rise of 20ºC above TCASE.
15. Converter delivers current into a persisting short circuit for up to 1 second. See Current Limit in the Application Notes section.
16. The specied operating case temperature for ES grade products is -45ºC to 100ºC. The specied operating case temperature for C grade
products is 0ºC to 70ºC
Doc.# 005-MQ2750S Rev. GProduct# MQFL-270-05S Phone 1-888-567-9596 www.SynQor.com 08/13/13
Page 5
Technical Figures
MQFL-270-05S
Output: 5.0V
Current: 24A
60
65
70
75
80
85
90
95
100
0 4 8 12 16 20 24
Load Current (A)
Efficiency (%)
155 Vin
270 Vin
400 Vin
60
65
70
75
80
85
90
95
100
-55ºC 25ºC 125ºC
Case Temperature (ºC)
Efficiency (%)
155 Vin
270 Vin
400 Vin
0
2
4
6
8
10
12
14
16
18
20
0 4 8 12 16 20 24
Power Dissipation (W)
155 Vin
270 Vin
400 Vin
0
2
4
6
8
10
12
14
16
18
20
-55ºC 25ºC 125ºC
Case Temperature (ºC)
Power Dissipation (W)
155 Vin
270 Vin
400 Vin
0
4
8
12
16
20
24
28
32
25 45 65 85 105 125 145
Case Temperature (ºC)
Iout (A)
0
20
40
60
80
100
120
140
160
= 105ºC
= 125ºC
= 145ºC
Pout (W)
0
1
2
3
4
5
6
0 5 10 15 20 25 30
Load Current (A)
Output Voltage (V)
270 Vin
Figure 1: Efciency at nominal output voltage vs. load current for
minimum, nominal, and maximum input voltage at TCASE=25°C.
Figure 2: Efciency at nominal output voltage and 60% rated power vs.
case temperature for input voltage of 155V, 270V and 400V.
Figure 3: Power dissipation at nominal output voltage vs. load current
for minimum, nominal, and maximum input voltage at Tcase=25°C.
Figure 4: Power dissipation at nominal output voltage and 60% rated
power vs. case temperature for input voltage of 155V, 270V and 400V.
Figure 5: Output Current / Output Power derating curve as a
function of Tcase and the Maximum desired power MOSFET junction
temperature (see Note 14). Vin = 270V
Figure 6: Output voltage vs. load current showing typical current limit
curves. See Current Limit section in the Application Notes.
Doc.# 005-MQ2750S Rev. GProduct# MQFL-270-05S Phone 1-888-567-9596 www.SynQor.com 08/13/13
Page 6
Technical Figures
MQFL-270-05S
Output: 5.0V
Current: 24A
Figure 7: Turn-on transient at full resistive load and zero output
capacitance initiated by ENA1. Input voltage pre-applied. Ch 1: Vout
(2V/div). Ch 2: ENA1 (5V/div).
Figure 8: Turn-on transient at full resistive load and 3mF output
capacitance initiated by ENA1. Input voltage pre-applied. Ch 1: Vout
(2V/div). Ch 2: ENA1 (5V/div).
Figure 9: Turn-on transient at full resistive load and zero output
capacitance initiated by ENA2. Input voltage pre-applied. Ch 1: Vout
(2V/div). Ch 2: ENA2 (5V/div).
Figure 10: Turn-on transient at full resistive load and zero output
capacitance initiated by Vin. ENA1 and ENA2 both previously high. Ch
1: Vout (2V/div). Ch 2: Vin (100V/div).
Figure 11: Output voltage response to step-change in load current
50%-100%-50% of Iout (max). Load cap: 1µF ceramic cap and 10µF,
100mΩ ESR tantalum cap. Ch 1: Vout (500mV/div). Ch 2: Iout (10A/
div).
Figure 12: Output voltage response to step-change in load current 10%-
50%-10% of Iout (max). Load cap: 1µF ceramic cap and 10µF, 100mΩ
ESR tantalum cap. Ch 1: Vout (500mV/div). Ch 2: Iout (10A/div).
Doc.# 005-MQ2750S Rev. GProduct# MQFL-270-05S Phone 1-888-567-9596 www.SynQor.com 08/13/13
Page 7
Technical Figures
MQFL-270-05S
Output: 5.0V
Current: 24A
Figure 13: Output voltage response to step-change in input voltage (155V
- 400V - 155V) in 250 μS. Load cap: 10µF, 100mΩ ESR tantalum cap and
1µF ceramic cap. Ch 1: Vin (100V/div). Ch 2: Vout (500mV/div).
Figure 14: Test set-up diagram showing measurement points for Input
Terminal Ripple Current (Figure 15) and Output Voltage Ripple (Figure
16).
Figure 17: Rise of output voltage after the removal of a short circuit
across the output terminals. Ch 1: Vout (2V/div). Ch 2: Iout (10A/div).
Figure 18: SYNC OUT vs. time, driving SYNC IN of a second SynQor
MQFL converter. Ch1: SYNC OUT: (1V/div).
Figure 15: Input terminal current ripple, ic, at full rated output current
and nominal input voltage with SynQor MQ lter module (50mA/div).
Bandwidth: 20MHz. See Figure 14.
Figure 16: Output voltage ripple, Vout, at nominal input voltage
and rated load current (10mV/div). Load capacitance: 1µF ceramic
capacitor and 10µF tantalum capacitor. Bandwidth: 10MHz. See
Figure 14.
Doc.# 005-MQ2750S Rev. GProduct# MQFL-270-05S Phone 1-888-567-9596 www.SynQor.com 08/13/13
Page 8
Technical Figures
MQFL-270-05S
Output: 5.0V
Current: 24A
0.001
0.01
0.1
1
10 100 1,000 10,000 100,000
Hz
Output Impedance (ohms)
155V
270V
400V
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
100 1,000 10,000 100,000
Hz
Forward Transmission (dB)
155V
270V
400V
-55
-45
-35
-25
-15
-5
5
10 100 1,000 10,000 100,000
Hz
Reverse Transmission (dB)
155V
270V
400V
1
10
100
1000
10000
10 100 1,000 10,000 100,000
Hz
Input Impedance (ohms)
155V
270V
400V
Figure 19: Magnitude of incremental output impedance (Zout = vout/
iout) for minimum, nominal, and maximum input voltage at full rated
power.
Figure 20: Magnitude of incremental forward transmission (FT = vout/
vin) for minimum, nominal, and maximum input voltage at full rated
power.
Figure 21: Magnitude of incremental reverse transmission (RT = iin/
iout) for minimum, nominal, and maximum input voltage at full rated
power.
Figure 22: Magnitude of incremental input impedance (Zin = vin/iin)
for minimum, nominal, and maximum input voltage at full rated power.
Figure 23: High frequency conducted emissions of standalone MQFL-
270-05S, 5Vout module at 120W output, as measured with Method
CE102. Limit line shown is the ‘Basic Curve’ for all applications with a
270V source.
Figure 24: High frequency conducted emissions of MQFL-270-05S,
5Vout module at 120W output with MQFL-270-P lter, as measured
with Method CE102. Limit line shown is the ‘Basic Curve’ for all
applications with a 270V source.
Doc.# 005-MQ2750S Rev. GProduct# MQFL-270-05S Phone 1-888-567-9596 www.SynQor.com 08/13/13
Page 9
BASIC OPERATION AND FEATURES
The MQFL DC-DC converter uses a two-stage power conversion
topology. The first, or regulation, stage is a buck-converter that
keeps the output voltage constant over variations in line, load,
and temperature. The second, or isolation, stage uses trans-
formers to provide the functions of input/output isolation and
voltage transformation to achieve the output voltage required.
Both the regulation and the isolation stages switch at a fixed
frequency for predictable EMI performance. The isolation stage
switches at one half the frequency of the regulation stage, but
due to the push-pull nature of this stage it creates a ripple at
double its switching frequency. As a result, both the input and
the output of the converter have a fundamental ripple frequency
of about 550 kHz in the free-running mode.
Rectification of the isolation stage’s output is accomplished with
synchronous rectifiers. These devices, which are MOSFETs with a
very low resistance, dissipate far less energy than would Schottky
diodes. This is the primary reason why the MQFL converters have
such high efficiency, particularly at low output voltages.
Besides improving efficiency, the synchronous rectifiers permit
operation down to zero load current. There is no longer a need
for a minimum load, as is typical for converters that use diodes
for rectification. The synchronous rectifiers actually permit a
negative load current to flow back into the converter’s output
terminals if the load is a source of short or long term energy.
The MQFL converters employ a “back-drive current limit” to
keep this negative output terminal current small.
There is a control circuit on both the input and output sides
of the MQFL converter that determines the conduction state
of the power switches. These circuits communicate with each
other across the isolation barrier through a magnetically coupled
device. No opto-isolators are used. A separate bias supply pro-
vides power to both the input and output control circuits.
An input under-voltage lockout feature with hysteresis is pro-
vided, as well as an input over-voltage shutdown. There is also
an output current limit that is nearly constant as the load imped-
ance decreases to a short circuit (i.e., there is no fold-back or
fold-forward characteristic to the output current under this con-
dition). When a load fault is removed, the output voltage rises
exponentially to its nominal value without an overshoot.
The MQFL converter’s control circuit does not implement an out-
put over-voltage limit or an over-temperature shutdown.
The following sections describe the use and operation of addi-
tional control features provided by the MQFL converter.
CONTROL FEATURES
ENABLE: The MQFL converter has two enable pins. Both must
have a logic high level for the converter to be enabled. A logic
low on either pin will inhibit the converter.
The ENA1 pin (pin 4) is referenced with respect to the convert-
er’s input return (pin 2). The ENA2 pin (pin 12) is referenced
with respect to the converter’s output return (pin 8). This per-
mits the converter to be inhibited from either the input or the
output side.
Regardless of which pin is used to inhibit the converter, the
regulation and the isolation stages are turned off. However,
when the converter is inhibited through the ENA1 pin, the bias
supply is also turned off, whereas this supply remains on when
the converter is inhibited through the ENA2 pin. A higher input
standby current therefore results in the latter case.
Both enable pins are internally pulled high so that an open con-
nection on both pins will enable the converter. Figure A shows
the equivalent circuit looking into either enable pins. It is TTL
compatible.
SHUT DOWN: The MQFL converter will shut down in response
to following conditions:
- ENA1 input low
- ENA2 input low
- VIN input below under-voltage lockout threshold
- VIN input above over-voltage shutdown threshold
- Persistent current limit event lasting more than 1 second
Following a shutdown from a disable event or an input voltage
fault, there is a startup inhibit delay which will prevent the
converter from restarting for approximately 300ms. After the
300ms delay elapses, if the enable inputs are high and the input
voltage is within the operating range, the converter will restart.
If the VIN input is brought down to nearly 0V and back into the
2N3904
1N4148
250K
125K
68K
5.0V
TO ENABLE
CIRCUITRY
PIN 4
(OR PIN 12)
PIN 2
(OR PIN 8) IN RTN
ENABLE
Figure A: Circuit diagram shown for reference only, actual circuit
components may differ from values shown for equivalent circuit.
Application Section
MQFL-270-05S
Output: 5.0V
Current: 24A
Doc.# 005-MQ2750S Rev. GProduct# MQFL-270-05S Phone 1-888-567-9596 www.SynQor.com 08/13/13
Page 10
operating range, there is no startup inhibit, and the output voltage
will rise according to the “Turn-On Delay, Rising Vin” specification.
Refer to the following Current Limit section for details regarding
persistent current limit behavior.
REMOTE SENSE: The purpose of the remote sense pins is
to correct for the voltage drop along the conductors that con-
nect the converter’s output to the load. To achieve this goal, a
separate conductor should be used to connect the +SENSE pin
(pin 10) directly to the positive terminal of the load, as shown
in the connection diagram. Similarly, the –SENSE pin (pin 9)
should be connected through a separate conductor to the return
terminal of the load.
NOTE: Even if remote sensing of the load voltage is not desired,
the +SENSE and the -SENSE pins must be connected to +Vout
(pin 7) and OUTPUT RETURN (pin 8), respectively, to get proper
regulation of the converter’s output. If they are left open, the
converter will have an output voltage that is approximately
200mV higher than its specified value. If only the +SENSE pin
is left open, the output voltage will be approximately 25mV too
high.
Inside the converter, +SENSE is connected to +Vout with a
100W resistor and –SENSE is connected to OUTPUT RETURN
with a 10W resistor.
It is also important to note that when remote sense is used, the
voltage across the converter’s output terminals (pins 7 and 8)
will be higher than the converter’s nominal output voltage due
to resistive drops along the connecting wires. This higher volt-
age at the terminals produces a greater voltage stress on the
converter’s internal components and may cause the converter to
fail to deliver the desired output voltage at the low end of the
input voltage range at the higher end of the load current and
temperature range. Please consult the factory for details.
SYNCHRONIZATION: The MQFL converter’s switching fre-
quency can be synchronized to an external frequency source
that is in the 500 kHz to 700 kHz range. A pulse train at the
desired frequency should be applied to the SYNC IN pin (pin
6) with respect to the INPUT RETURN (pin 2). This pulse train
should have a duty cycle in the 20% to 80% range. Its low
value should be below 0.8V to be guaranteed to be interpreted
as a logic low, and its high value should be above 2.0V to be
guaranteed to be interpreted as a logic high. The transition time
between the two states should be less than 300ns.
If the MQFL converter is not to be synchronized, the SYNC IN pin
should be left open circuit. The converter will then operate in
its free-running mode at a frequency of approximately 550 kHz.
If, due to a fault, the SYNC IN pin is held in either a logic low or
logic high state continuously, the MQFL converter will revert to
its free-running frequency.
The MQFL converter also has a SYNC OUT pin (pin 5). This out-
put can be used to drive the SYNC IN pins of as many as ten (10)
other MQFL converters. The pulse train coming out of SYNC
OUT has a duty cycle of 50% and a frequency that matches the
switching frequency of the converter with which it is associated.
This frequency is either the free-running frequency if there is no
synchronization signal at the SYNC IN pin, or the synchronization
frequency if there is.
The SYNC OUT signal is available only when the DC input volt-
age is above approximately 125V and when the converter is not
inhibited through the ENA1 pin. An inhibit through the ENA2 pin
will not turn the SYNC OUT signal off.
NOTE: An MQFL converter that has its SYNC IN pin driven by
the SYNC OUT pin of a second MQFL converter will have its start
of its switching cycle delayed approximately 180 degrees relative
to that of the second converter.
Figure B shows the equivalent circuit looking into the SYNC IN pin.
Figure C shows the equivalent circuit looking into the SYNC OUT pin.
Figure C: Equivalent circuit looking into SYNC OUT pin with
respect to the IN RTN (input return) pin.
FROM SYNC
CIRCUITRY
5K
5V
SYNC OUT
IN RTN PIN 2
PIN 5
OPEN COLLECTOR
OUTPUT
Figure B: Equivalent circuit looking into the SYNC IN pin with
respect to the IN RTN (input return) pin.
PIN 2
PIN 6
5K
5V
SYNC IN
IN RTN
TO SYNC
CIRCUITRY
5K
Application Section
MQFL-270-05S
Output: 5.0V
Current: 24A
Doc.# 005-MQ2750S Rev. GProduct# MQFL-270-05S Phone 1-888-567-9596 www.SynQor.com 08/13/13
Page 11
CURRENT SHARE: When several MQFL converters are placed
in parallel to achieve either a higher total load power or N+1
redundancy, their SHARE pins (pin 11) should be connected
together. The voltage on this common SHARE node represents
the average current delivered by all of the paralleled converters.
Each converter monitors this average value and adjusts itself
so that its output current closely matches that of the average.
Since the SHARE pin is monitored with respect to the OUTPUT
RETURN (pin 8) by each converter, it is important to connect
all of the converters’ OUTPUT RETURN pins together through a
low DC and AC impedance. When this is done correctly, the
converters will deliver their appropriate fraction of the total load
current to within +/- 10% at full rated load.
Whether or not converters are paralleled, the voltage at the
SHARE pin could be used to monitor the approximate average
current delivered by the converter(s). A nominal voltage of 1.0V
represents zero current and a nominal voltage of 2.2V repre-
sents the maximum rated total current, with a linear relationship
in between. The internal source resistance of a converter’s
SHARE pin signal is 2.5 kW.
During an input voltage fault or primary disable event, the
SHARE pin outputs a power failure warning pulse. The SHARE
pin will go to 3V for approximately 14ms as the output voltage
falls. During a current limit auto-restart event, the SHARE pin
outputs a startup synchronization pulse. The SHARE pin will go
to 5V for approximately 2ms before the converter restarts.
NOTE: Converters operating from separate input filters with
reverse polarity protection (such as the MQME-270-R filter)
with their outputs connected in parallel may exhibit auto-restart
operation at light loads. Consult factory for details.
OUTPUT VOLTAGE TRIM: If desired, it is possible to increase
the MQFL converter’s output voltage above its nominal value.
To do this, use the +SENSE pin (pin 10) for this trim function
instead of for its normal remote sense function, as shown in
Figure D. In this case, a resistor connects the +SENSE pin to
the –SENSE pin (which should still be connected to the output
return, either remotely or locally). The value of the trim resistor
should be chosen according to the following equation or from
Figure E:
where:
Vnom = the converter’s nominal output voltage,
Vout = the desired output voltage (greater than Vnom), and
Rtrim is in Ohms.
As the output voltage is trimmed up, it produces a greater
voltage stress on the converter’s internal components and may
cause the converter to fail to deliver the desired output voltage
at the low end of the input voltage range at the higher end of
the load current and temperature range. Please consult the
factory for details. Factory trimmed converters are available
by request.
100
1,000
10,000
100,000
0 0.1 0.2 0.3 0.4 0.5 0.6
Increase in Vout (V)
Trim Resistance (ohms)
Figure E: Output Voltage Trim Graph
Figure D: Typical connection for output voltage trimming.
270Vdc
Load
+VIN
IN RTN
CASE
ENA 1
SYNC OUT
SYNC IN
ENA 2
SHARE
+ SNS
– SNS
OUT RTN
+VOUT
1
2
3
4
5
6
12
11
10
9
8
7
open
means
on
Rtrim
+
–
+
–
Rtrim = 100 x
Vnom
Vout - Vnom - 0.025
Application Section
MQFL-270-05S
Output: 5.0V
Current: 24A
Doc.# 005-MQ2750S Rev. GProduct# MQFL-270-05S Phone 1-888-567-9596 www.SynQor.com 08/13/13
Page 12
INPUT UNDER-VOLTAGE LOCKOUT: The MQFL converter
has an under-voltage lockout feature that ensures the converter
will be off if the input voltage is too low. The threshold of
input voltage at which the converter will turn on is higher that
the threshold at which it will turn off. In addition, the MQFL
converter will not respond to a state of the input voltage unless
it has remained in that state for more than about 200
µ
s. This
hysteresis and the delay ensure proper operation when the
source impedance is high or in a noisy environment.
INPUT OVER-VOLTAGE SHUTDOWN: The MQFL converter
also has an over-voltage feature that ensures the converter will
be off if the input voltage is too high. It also has a hysteresis
and time delay to ensure proper operation.
CURRENT LIMIT: The converter will reduce its output volt-
age in response to an overload condition. If the output voltage
drops to below approximately 50% of the nominal setpoint for
longer than 1 second, the auto-restart feature will engage. The
auto-restart feature will stop the converter from delivering load
current, in order to protect the converter and the load from ther-
mal damage. After four seconds have elapsed, the converter will
automatically restart.
In a system with multiple converters configured for load sharing
using the SHARE pin, if the auto-restart feature engages,
the converters will synchronize their restart using signals
communicated on the SHARE pin.
BACK-DRIVE CURRENT LIMIT: Converters that use MOSFETs
as synchronous rectifiers are capable of drawing a negative cur-
rent from the load if the load is a source of short- or long-term
energy. This negative current is referred to as a “back-drive cur-
rent”.
Conditions where back-drive current might occur include
paralleled converters that do not employ current sharing, or
where the current share feature does not adequately ensure
sharing during the startup or shutdown transitions. It can also
occur when converters having different output voltages are
connected together through either explicit or parasitic diodes
that, while normally off, become conductive during startup or
shutdown. Finally, some loads, such as motors, can return
energy to their power rail. Even a load capacitor is a source of
back-drive energy for some period of time during a shutdown
transient.
To avoid any problems that might arise due to back-drive
current, the MQFL converters limit the negative current that the
converter can draw from its output terminals. The threshold
for this back-drive current limit is placed sufficiently below zero
so that the converter may operate properly down to zero load,
but its absolute value (see the Electrical Characteristics page) is
small compared to the converter’s rated output current.
THERMAL CONSIDERATIONS: The suggested Power Derating
Curves for this converter as a function of the case temperature
and the maximum desired power MOSFET junction temperature
on the figures page. All other components within the converter
are cooler than its hottest MOSFET, which at full power is no
more than 20ºC higher than the case temperature directly
below this MOSFET. The Mil-HDBK-1547A component derating
guideline calls for a maximum component temperature of 105ºC.
The power derating figure; therefore has one power derating
curve that ensures this limit is maintained. It has been SynQor’s
extensive experience that reliable long-term converter operation
can be achieved with a maximum component temperature of
125ºC. In extreme cases, a maximum temperature of 145ºC is
permissible, but not recommended for long-term operation where
high reliability is required. Derating curves for these higher
temperature limits are also included in Figure 5. The maximum
case temperature at which the converter should be operated is
135ºC.
When the converter is mounted on a metal plate, the plate
will help to make the converter’s case bottom a uniform tem-
perature. How well it does so depends on the thickness of the
plate and on the thermal conductance of the interface layer
(e.g. thermal grease, thermal pad, etc.) between the case and
the plate. Unless this is done very well, it is important not to
mistake the plate’s temperature for the maximum case tempera-
ture. It is easy for them to be as much as 5-10ºC different at
full power and at high temperatures. It is suggested that a ther-
mocouple be attached directly to the converter’s case through a
small hole in the plate when investigating how hot the converter
is getting. Care must also be made to ensure that there is not
a large thermal resistance between the thermocouple and the
case due to whatever adhesive might be used to hold the ther-
mocouple in place.
INPUT SYSTEM INSTABILITY: This
condition can occur
because any DC-DC converter appears incrementally as a
negative resistance load. A detailed application note titled
“Input System Instability” is available on the SynQor website
which provides an understanding of why this instability arises,
and shows the preferred solution for correcting it.
Application Section
MQFL-270-05S
Output: 5.0V
Current: 24A
Doc.# 005-MQ2750S Rev. GProduct# MQFL-270-05S Phone 1-888-567-9596 www.SynQor.com 08/13/13
Page 13
Stress Screening
MQFL-270-05S
Output: 5.0V
Current: 24A
CONSTRUCTION AND ENVIRONMENTAL STRESS SCREENING OPTIONS
Screening Consistent with
MIL-STD-883F
C-Grade ES-Grade HB-Grade
(specied from ) ( specied from ) ( specied from )
0 ºC to +70 ºC -45 ºC to +100 ºC -55 ºC to +125 ºC
Element Evaluation No Yes Yes
Internal Visual * Yes Yes Yes
Temperature Cycle Method 1010 No Condition B
(-55 ºC to +125 ºC)
Condition C
(-65 ºC to +150 ºC)
Constant Acceleration Method 2001
(Y1 Direction) No 500g Condition A
(5000g)
Burn-in Method 1015 24 Hrs @ +125 ºC 96 Hrs @ +125 ºC 160 Hrs @ +125 ºC
Final Electrical Test Method 5005 (Group A) +25 ºC -45, +25, +100 ºC -55, +25, +125 ºC
Mechanical Seal,
Thermal, and
Coating Process
Full QorSeal Full QorSeal Full QorSeal
External Visual 2009 * Yes Yes
Construction Process QorSeal QorSeal QorSeal
* Per IPC-A-610 Class 3
MilQor converters and lters are offered in three variations of environmental stress screening options. All MilQor converters use SynQor’s proprietary
QorSeal™ Hi-Rel assembly process that includes a Parylene-C coating of the circuit, a high performance thermal compound ller, and a nickel barrier
gold plated aluminum case. Each successively higher grade has more stringent mechanical and electrical testing, as well as a longer burn-in cycle. The ES-
and HB-Grades are also constructed of components that have been procured through an element evaluation process that pre-qualies each new batch of
devices.
Doc.# 005-MQ2750S Rev. GProduct# MQFL-270-05S Phone 1-888-567-9596 www.SynQor.com 08/13/13
Page 14
MADE IN USA
1
2
3
4
5
6
12
11
10
9
8
7
1.260
[32.00]
1.50 [38.1]
0.128 [3.25]
0.22 [5.6]
0.42
[10.7] 0.050 [1.27]
0.040
[1.02]
PIN
0.200 [5.08]
TYP.
NON-CUM.
0.250 [6.35]
0.390 [9.91]
2.50 [63.5]
2.760 [70.10]
3.00 [76.2]
SEE NOTE 7
S/N 0000000 D/C 3211-301 CAGE 1WX10
2.80 [71.1]
MADE IN USA
1
2
3
4
5
6
12
11
10
9
8
7
1.260
[32.00]
1.50 [38.1]
0.128 [3.25]
0.228 [5.79]
0.22 [5.6]
0.050 [1.27]
0.040 [1.02]
PIN
0.200 [5.08]
TYP. NON-CUM.
0.250 [6.35]
0.390 [9.91]
2.50 [63.50]
2.760 [70.10]
3.00 [76.2]
2.96 [75.2]
S/N 0000000 D/C 3205-301 CAGE 1WX10
SEE NOTE 7
Case X
Case U
PIN DESIGNATIONS
Pin # Function Pin # Function
1 Positive input 7 Positive output
2 Input return 8 Output return
3 Case 9 - Sense
4 Enable 1 10 + Sense
5 Sync output 11 Share
6 Sync input 12 Enable 2
NOTES
1) Pins 0.040’’ (1.02mm) diameter
2) Pin Material: Copper Alloy
Finish: Gold over Nickel plating, followed by Sn/Pb solder dip
3) All dimensions in inches (mm) Tolerances: x.xx +/-0.02 in. (x.x +/-0.5mm)
x.xxx +/-0.010 in. (x.xx +/-0.25mm)
4) Weight: 2.8 oz (78.5 g) typical
5) Workmanship: Meets or exceeds IPC-A-610 Class III
6) Print Labeling on Top Surface per Product Label Format Drawing
7) Pin 1 identication hole, not intended for mounting (case X and U)
8) Baseplate atness tolerance is 0.004” (.10mm) TIR for surface.
+VIN ENA 2
IN RTN SHARE
CASE +SNS
ENA 1 -SNS
SYNC OUT OUT RTN
SYNC IN +VOUT
+VIN ENA 2
IN RTN SHARE
CASE +SNS
ENA 1 -SNS
SYNC OUT OUT RTN
SYNC IN +VOUT
MQFL-270-05S-X-ES
DC-DC CONVERTER
270Vin 5.0Vout @ 24A
MQFL-270-05S-U-ES
DC-DC CONVERTER
270Vin 5.0Vout @ 24A
Mechanical Diagrams
MQFL-270-05S
Output: 5.0V
Current: 24A
Doc.# 005-MQ2750S Rev. GProduct# MQFL-270-05S Phone 1-888-567-9596 www.SynQor.com 08/13/13
Page 15
1
2
3
4
5
6
12
11
10
9
8
7
1.750
[44.45]
1.50
[38.1]
0.228 [5.79]
0.300 [7.62]
0.140 [3.56]
0.22 [5.6]
0.050 [1.27]
0.040 [1.02]
PIN
0.200 [5.08]
TYP. NON-CUM.
0.250 [6.35]
0.250 [6.35]
TYP
0.375 [9.52]
2.50 [63.5]
2.96 [75.2]
0.390 [9.91]
2.000
[50.80]
1.150 [29.21]
1.750 [44.45]
S/N 0000000 D/C 3211-301 CAGE 1WX10
MADE IN USA
0.390
[9.91]
0.050 [1.27]
0.36 [9.14]
0.250 [6.35]
0.22 [5.6]
2.80 [71.1]
0.525 [13.33]
0.040 [1.02]
PIN
0.200 [5.08]
TYP. NON-CUM.
0.390
[9.91]
0.050 [1.27]
0.250 [6.35]
0.22 [5.6]
0.42 [10.7]
2.80 [71.1]
0.525 [13.33]
0.040 [1.02]
PIN
0.200 [5.08]
TYP. NON-CUM.
Case Y
Case Z
(variant of Y)
Case W
(variant of Y)
PIN DESIGNATIONS
Pin # Function Pin # Function
1 Positive input 7 Positive output
2 Input return 8 Output return
3 Case 9 - Sense
4 Enable 1 10 + Sense
5 Sync output 11 Share
6 Sync input 12 Enable 2
NOTES
1) Pins 0.040’’ (1.02mm) diameter
2) Pin Material: Copper Alloy
Finish: Gold over Nickel plating, followed by Sn/Pb solder dip
3) All dimensions in inches (mm) Tolerances: x.xx +/-0.02 in. (x.x +/-0.5mm)
x.xxx +/-0.010 in. (x.xx +/-0.25mm)
4) Weight: 2.8 oz (78.5 g) typical
5) Workmanship: Meets or exceeds IPC-A-610 Class III
6) Print Labeling on Top Surface per Product Label Format Drawing
7) Pin 1 identication hole, not intended for mounting (case X and U)
8) Baseplate atness tolerance is 0.004” (.10mm) TIR for surface.
+VIN ENA 2
IN RTN SHARE
CASE +SNS
ENA 1 -SNS
SYNC OUT OUT RTN
SYNC IN +VOUT
MQFL-270-05S-Y-ES
DC-DC CONVERTER
270Vin 5.0Vout @ 24A
Mechanical Diagrams
MQFL-270-05S
Output: 5.0V
Current: 24A
Doc.# 005-MQ2750S Rev. GProduct# MQFL-270-05S Phone 1-888-567-9596 www.SynQor.com 08/13/13
Page 16
MilQor Converter FAMILY MATRIX
The tables below show the array of MilQor converters available. When ordering SynQor converters, please ensure that
you use the complete part number according to the table in the last page. Contact the factory for other requirements.
Single Output Dual Output †
Full Size 1.5V 1.8V 2.5V 3.3V 5V 6V 7.5V 9V 12V 15V 28V 5V 12V 15V
(1R5S) (1R8S) (2R5S) (3R3S) (05S) (06S) (7R5S) (09S) (12S) (15S) (28S) (05D) (12D) (15D)
MQFL-28
40A 40A 40A 30A 24A 20A 16A 13A 10A 8A 4A 24A
Total
10A
Total
8A
Total
16-40Vin Cont.
16-50Vin 1s Trans.*
Absolute Max Vin = 60V
MQFL-28E
40A 40A 40A 30A 24A 20A 16A 13A 10A 8A 4A 24A
Total
10A
Total
8A
Total
16-70Vin Cont.
16-80Vin 1s Trans.*
Absolute Max Vin =100V
MQFL-28V
40A 40A 40A 30A 20A 17A 13A 11A 8A 6.5A 3.3A
16-40Vin Cont.
5.5-50Vin 1s Trans.*
Absolute Max Vin = 60V
MQFL-28VE
40A 40A 40A 30A 20A 17A 13A 11A 8A 6.5A 3.3A
16-70Vin Cont.
5.5-80Vin 1s Trans.*
Absolute Max Vin = 100V
MQFL-270
40A 40A 40A 30A 24A 20A 16A 13A 10A 8A 4A 24A
Total
10A
Total
8A
Total
155-400Vin Cont.
155-475Vin 1s Trans.*
Absolute Max Vin = 550V
MQFL-270L
40A 40A 30A 22A 15A 12A 10A 8A 6A 5A 2.7A 15A
Total
6A
Total
5A
Total
65-350Vin Cont.
65-475Vin 1s Trans.*
Absolute Max Vin = 550V
Single Output Dual Output †
Half Size 1.5V 1.8V 2.5V 3.3V 5V 6V 7.5V 9V 12V 15V 28V 5V 12V 15V
(1R5S) (1R8S) (2R5S) (3R3S) (05S) (06S) (7R5S) (09S) (12S) (15S) (28S) (05D) (12D) (15D)
MQHL-28
20A 20A 20A 15A 10A 8A 6.6A 5.5A 4A 3.3A 1.8A 10A
Total
4A
Total
3.3A
Total
16-40Vin Cont.
16-50Vin 1s Trans.*
Absolute Max Vin = 60V
MQHL-28E
20A 20A 20A 15A 10A 8A 6.6A 5.5A 4A 3.3A 1.8A 10A
Total
4A
Total
3.3A
Total
16-70Vin Cont.
16-80Vin 1s Trans.*
Absolute Max Vin =100V
MQHR-28
10A 10A 10A 7.5A 5A 4A 3.3A 2.75A 2A 1.65A 0.9A 5A
Total
2A
Total
1.65A
Total
16-40Vin Cont.
16-50Vin 1s Trans.*
Absolute Max Vin = 60V
MQHR-28E
10A 10A 10A 7.5A 5A 4A 3.3A 2.75A 2A 1.65A 0.9A 5A
Total
2A
Total
1.65A
Total
16-70Vin Cont.
16-80Vin 1s Trans.*
Absolute Max Vin = 100V
Check with factory for availability.
†80% of total output current available on any one output.
*Converters may be operated at the highest transient input voltage, but some component electrical and thermal stresses would be beyond MIL-
HDBK-1547A guidelines.
Ordering Information
MQFL-270-05S
Output: 5.0V
Current: 24A
Doc.# 005-MQ2750S Rev. GProduct# MQFL-270-05S Phone 1-888-567-9596 www.SynQor.com 08/13/13
Page 17
Model
Name
Input
Voltage
Range
Output Voltage(s) Package Outline/
Pin Conguration
Screening
Grade
Single
Output
Dual
Output
MQFL
MQHL
MQHR
28
28E
28V
28VE
270
270L
1R5S
1R8S
2R5S
3R3S
05S
06S
7R5S
09S
12S
15S
28S
05D
12D
15D
U
X
Y
W
Z
C
ES
HB
Warranty
SynQor offers a two (2) year limited warranty. Complete warranty informa-
tion is listed on our website or is available upon request from SynQor.
Information furnished by SynQor is believed to be accurate and reliable.
However, no responsibility is assumed by SynQor for its use, nor for any
infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any
patent or patent rights of SynQor.
Contact SynQor for further information and to order:
Phone: 978-849-0600
Toll Free: 1-888-567-9596
Fax: 978-849-0602
E-mail: mqnbofae@synqor.com
Web:
www.synqor.com
Address: 155 Swanson Road
Boxborough, MA 01719
USA
PATENTS
SynQor holds the following U.S. patents, one or more of which apply to each product listed in this document. Additional patent applications may be
pending or led in the future.
5,999,417 6,222,742 6,545,890 6,577,109 6,594,159 6,731,520
6,894,468 6,896,526 6,927,987 7,050,309 7,072,190 7,085,146
7,119,524 7,269,034 7,272,021 7,272,023 7,558,083 7,564,702
7,765,687 7,787,261 8,023,290 8,149,597
APPLICATION NOTES
A variety of application notes and technical white papers can be downloaded in pdf format from the SynQor website.
PART NUMBERING SYSTEM
The part numbering system for SynQor’s MilQor DC-DC converters follows the format shown in the table below.
Not all combinations make valid part numbers, please contact SynQor for availability. See the Product Summary web page for more options.
Example: MQFL-270-05S-Y-ES
Ordering Information
MQFL-270-05S
Output: 5.0V
Current: 24A