MQFL-270-28S-Y-C - SynQor, Inc.

Doc.# 005-MQ2728S Rev. DProduct# MQFL-270-28S Phone 1-888-567-9596 www.SynQor.com 08/13/13

Page 1

MQFL-270-28S-Y-ES

270Vin 28Vout@4A

DC-DC CONVERTER

+VIN

IN RTN

CASE

ENA 1

SYNC OUT

SYNC IN

ENA 2

+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-270-28S

Single Output

155-400 V 155-475 V 28 V 4 A 88% @ 4 A / 86% @ 2 A

Continuous Input Transient Input Output Output Efciency

Doc.# 005-MQ2728S Rev. DProduct# MQFL-270-28S Phone 1-888-567-9596 www.SynQor.com 08/13/13

Page 2

Technical Specification

MQFL-270-28S

Output: 28V

Current: 4A

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

GATE DRIVERS

ISOLATION BARRIER

CURRENT

LIMIT

CURRENT

SENSE

BIAS POWER

TRANSFORMER

MAGNETIC

DATA COUPLING

SECONDARY

CONTROL

GATE DRIVERS

−

SENSE

+Vout

OUTPUT

RETURN

ENABLE 2

+ SENSE

T1 T2

MQFL

+VIN

IN RTN

CASE

ENA 1

SYNC OUT

SYNC IN

ENA 2

+SNS

-SNS

OUT RTN

+VOUT

Load

open

means

270 Vdc

open

means

Doc.# 005-MQ2728S Rev. DProduct# MQFL-270-28S Phone 1-888-567-9596 www.SynQor.com 08/13/13

Page 3

Technical Specification

MQFL-270-28S

Output: 28V

Current: 4A

MQFL-270-28S ELECTRICAL CHARACTERISTICS

Parameter Min. Typ. Max. Units Notes & Conditions Group A

Vin=270 V dc ±5%, Iout=4 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 A

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 = 4 A 1, 2, 3

No Load Input Current (operating) 28 35 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) 27.72 28.00 28.28 V Vout at sense leads 1

Vout Set Point Over Temperature 27.60 28.00 28.40 V “ 2, 3

Output Voltage Line Regulation -20 0 20 mV “ ; Vin = 155 V, 270 V, 400 V; Iout=4 A 1, 2, 3

Output Voltage Load Regulation 120 135 150 mV “ ; Vout @ (Iout=0 A) - Vout @ (Iout=4 A) 1, 2, 3

Total Output Voltage Range 27.44 28.00 28.56 V “ 1, 2, 3

Vout Ripple and Noise Peak to Peak 45 90 mV Bandwidth = 10 MHz; CL=11µF 1, 2, 3

Operating Output Current Range 0 4 A 1, 2, 3

Operating Output Power Range 0 112 W 1, 2, 3

Output DC Current-Limit Inception 4.1 4.7 5.3 A See Note 4 1, 2, 3

Short Circuit Output Current 4.1 4.8 5.5 A Vout ≤ 1.2 V; see Note 15 1, 2, 3

Back-Drive Current Limit while Enabled 1.5 A 1, 2, 3

Back-Drive Current Limit while Disabled 10 50 mA 1, 2, 3

Maximum Output Capacitance 3,000 µF See Note 5

DYNAMIC CHARACTERISTICS

Output Voltage Deviation Load Transient See Note 6

For a Pos. Step Change in Load Current -2500 -2000 mV Total Iout step = 2A‹-›4A, 0.4A‹-›2A; CL=11µF 4, 5, 6

For a Neg. Step Change in Load Current 2000 2500 mV “ 4, 5, 6

Settling Time (either case) 300 500 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 3500 4500 mV “ 4, 5, 6

For a Neg. Step Change in Line Voltage -4500 4500 mV “ 4, 5, 6

Settling Time (either case) 500 700 µs Iout = 2 A; See Note 7 See Note 5

Turn-On Transient

Output Voltage Rise Time 6 10 ms Vout = 2.8 V-›25.2 V 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 = 4 A (155 Vin) 85 89 % 1, 2, 3

Iout = 2 A (155 Vin) 90 % 1, 2, 3

Iout = 4 A (270 Vin) 84 88 % 1, 2, 3

Iout = 2 A (270 Vin) 81 86 % 1, 2, 3

Iout = 4 A (400 Vin) 81 86 % 1, 2, 3

Iout = 2 A (400 Vin) 82 % 1, 2, 3

Load Fault Power Dissipation 22 32 W Iout at current limit inception point ; See Note 4 1, 2, 3

Short Circuit Power Dissipation 22 24 W Vout ≤ 1.2 V; see Note 15 See Note 5

Doc.# 005-MQ2728S Rev. DProduct# MQFL-270-28S Phone 1-888-567-9596 www.SynQor.com 08/13/13

Page 4

Technical Specification

MQFL-270-28S

Output: 28V

Current: 4A

MQFL-270-28S ELECTRICAL CHARACTERISTICS (Continued)

Parameter Min. Typ. Max. Units Notes & Conditions Group A

Vin=270 V dc ±5%, Iout=4 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 ≥ 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-MQ2728S Rev. DProduct# MQFL-270-28S Phone 1-888-567-9596 www.SynQor.com 08/13/13

Page 5

Technical Figures

MQFL-270-28S

Output: 28V

Current: 4A

100

0 1 2 3 4

Efficiency (%)

Load Current (A)

155 Vin

270 Vin

400 Vin

100

-55ºC

25ºC

125ºC

Efficiency (%)

Case Temperature (ºC)

155 Vin

270 Vin

400 Vin

0 1 2 3 4

Power Dissipation (W)

Load Current (A)

155 Vin

270 Vin

400 Vin

-55ºC

25ºC

125ºC

Power Dissipation (W)

Case Temperature (ºC)

155 Vin

270 Vin

400 Vin

112

140

168

25 45 65 85 105 125 145

Iout (A)

Case Temperature (ºC)

Tjmax = 105º C

Tjmax = 125º C

Tjmax = 145º C

Pout (W)

012345

Output Voltage (V)

Load Current (A)

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-MQ2728S Rev. DProduct# MQFL-270-28S Phone 1-888-567-9596 www.SynQor.com 08/13/13

Page 6

Technical Figures

MQFL-270-28S

Output: 28V

Current: 4A

Figure 7: Turn-on transient at full resistive load and zero output

capacitance initiated by ENA1. Input voltage pre-applied. Ch 1: Vout

(10V/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

(10V/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

(10V/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 (10V/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 (2V/div). Ch 2: Iout (2A/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 (1V/div). Ch 2: Iout (2A/div).

Doc.# 005-MQ2728S Rev. DProduct# MQFL-270-28S Phone 1-888-567-9596 www.SynQor.com 08/13/13

Page 7

Technical Figures

MQFL-270-28S

Output: 28V

Current: 4A

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 (2V/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 (10V/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 (20mV/div). Load capacitance: 1µF ceramic

capacitor and 10µF tantalum capacitor. Bandwidth: 10MHz. See

Figure 14.

Doc.# 005-MQ2728S Rev. DProduct# MQFL-270-28S Phone 1-888-567-9596 www.SynQor.com 08/13/13

Page 8

Technical Figures

MQFL-270-28S

Output: 28V

Current: 4A

0.01

0.1

10 100 1,000 10,000 100,000

Output Impedance (ohms)

155 Vin

270 Vin

400 Vin

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

10 100 1,000 10,000 100,000

Forward Transmission (dB)

155 Vin

270 Vin

400 Vin

-55

-45

-35

-25

-15

-5

10 100 1,000 10,000 100,000

Reverse Transmission (dB)

155 Vin

270 Vin

400 Vin

100

1000

10000

10 100 1,000 10,000 100,000

Input Impedance (ohms)

155 Vin

270 Vin

400 Vin

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 8Basic Curve for all

applications with a 270V source.

Doc.# 005-MQ2728S Rev. DProduct# MQFL-270-28S 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-270-28S

Output: 28V

Current: 4A

Doc.# 005-MQ2728S Rev. DProduct# MQFL-270-28S 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

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

SYNC IN

IN RTN

TO SYNC

CIRCUITRY

Application Section

MQFL-270-28S

Output: 28V

Current: 4A

Doc.# 005-MQ2728S Rev. DProduct# MQFL-270-28S 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 0.5 1 1.5 2 2.5 3

Trim Resistance (ohms)

Increase in Vout (V)

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

+ SNS

– SNS

OUT RTN

+VOUT

open

means

Rtrim

–

Rtrim = 100 x

Vnom

Vout - Vnom - 0.025

Application Section

MQFL-270-28S

Output: 28V

Current: 4A

Doc.# 005-MQ2728S Rev. DProduct# MQFL-270-28S 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

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-270-28S

Output: 28V

Current: 4A

Doc.# 005-MQ2728S Rev. DProduct# MQFL-270-28S Phone 1-888-567-9596 www.SynQor.com 08/13/13

Page 13

Stress Screening

MQFL-270-28S

Output: 28V

Current: 4A

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-MQ2728S Rev. DProduct# MQFL-270-28S Phone 1-888-567-9596 www.SynQor.com 08/13/13

Page 14

MADE IN USA

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]

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

1.260

[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]

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-270-28S-X-ES

DC-DC CONVERTER

270Vin 28Vout @ 4A

MQFL-270-28S-U-ES

DC-DC CONVERTER

270Vin 28Vout @ 4A

Mechanical Diagrams

MQFL-270-28S

Output: 28V

Current: 4A

Doc.# 005-MQ2728S Rev. DProduct# MQFL-270-28S Phone 1-888-567-9596 www.SynQor.com 08/13/13

Page 15

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]

0.200 [5.08]

TYP. NON-CUM.

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]

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]

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-270-28S-Y-ES

DC-DC CONVERTER

270Vin 28Vout @ 4A

Mechanical Diagrams

MQFL-270-28S

Output: 28V

Current: 4A

Doc.# 005-MQ2728S Rev. DProduct# MQFL-270-28S 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

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

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

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

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

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

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

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

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-270-28S

Output: 28V

Current: 4A

Doc.# 005-MQ2728S Rev. DProduct# MQFL-270-28S 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

28E

28V

28VE

270

270L

1R5S

1R8S

2R5S

3R3S

05S

06S

7R5S

09S

12S

15S

28S

05D

12D

15D

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-270-28S-Y-ES

Ordering Information

MQFL-270-28S

Output: 28V

Current: 4A