Product # SQ60120QPA28 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2SQ612J Rev. G 03/29/11 Page 1
Technical
Specification
SQ60120QPA28
36-75V 100V 12V 336W 2250V dc Quarter-brick
Input Transient Input Output Max Power Isolation DC-DC Converter
Contents
®
Bus
Operational Features
• High efciency, 95% at full rated load current
• Delivers up to 28A of output current (336W power)
with minimal derating - no heatsink required
• Wide input voltage range: 36-75V, with
100V 100ms input voltage transient capability
• Fixed frequency switching provides predictable EMI performance
• No minimun load requirement Protection Features
• Input under-voltage lockout and over-voltage shutdown protects
against abnormal input voltages
• Output current limit and short circuit protection
• Output over-voltage protection
• Thermal shutdown
SQ60120QPA28 Model
Control Features
• On/Off control referenced to input side
• Inherent current share (by droop method) for high current and
parallel applications.
Mechanical Features
• Industry standard quarter-brick pin-out conguration
• Industry standard size: 2.30" x 1.45" (58.4 x 36.8mm)
• Total Open Frame height: 0.48” (12.3mm)
• Total Open Frame weight: 1.5 oz (42 g)
The SQ60120QPA28 bus converter is a next-generation,
board-mountable, isolated, xed switching frequency dc-
dc converter that uses synchronous rectication to achieve
extremely high conversion efciency. The SQ BusQor series
provides an isolated step down voltage from 48V to a semi-
regulated 12V intermediate bus. BusQor converters are
ideal for customers who need multiple outputs and wish to
build or buy point of load converters to work with a 12V rail.
RoHS Compliant (see last page).
Safety Features
• UL 60950-1:2007
• EN60950-1/A11:2009/A1:2010
• CAN/CSA-C22.2 No. 60950-1:2007
• IEC 61000-4-2
Page No.
Open Frame Mechanical Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Electrical Characteristics................................... 3
Standards & Qualifications ................................. 5
Figures............................................... 6
Application Section ..................................... 10
Ordering Information.................................... 14
Product # SQ60120QPA28 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2SQ612J Rev. G 03/29/11 Page 2
Technical
Specification
SQ60120QPA28
Open Frame Mechanical Diagram
Open Frame Mechanical Diagram
2.30
[58,4]
.43[10,8]
.300[7,62]
.600[15,24]
.600[15,24]
1.45[36,8]
.14
[3,6]
BOTTOMSIDE
CLEARANCE
.033± .032
0,84± 0,81[ ]
.145
[3,68]
SEE NOTE 5
OVERALL HEIGHT
.483± .032
12,27± 0,81[ ]
TOP VIEW SIDE VIEW
123
6 5
NOTES
1) Pins 1-3 are 0.040” (1.02mm) diameter, with 0.080” (2.03mm)
diameter standoff shoulders.
2) Pins 5-6 are 0.062” (1.57 mm) diameter with 0.100” (2.54mm)
diameter standoff shoulders.
3) Other pin lengths available. Recommended pin length is 0.03”
(0.76mm) greater than the PCB thickness.
4) All Pins: Material - Copper Alloy
Finish: Matte Tin over Nickel plate
5) Undimensioned components are shown for visual reference only.
6) All dimensions in inches (mm)
Tolerances: x.xx +/-0.02 in. (x.x +/-0.5mm)
x.xxx +/-0.010 in. (x.xx +/-0.25mm)
7) Total OF weight: 1.5 oz (42 g)
8) Workmanship: Meets or exceeds current IPC-A-610 Class II
9) UL/TUV standards require a clearance of 0.04” (1.02mm) around
primary areas of the module.
10) The anged pins are designed to permit surface mount soldering
(allowing to avoid the wave soldering process) through the use of
the anged pin-in-paste technique.
PIN DESIGNATIONS
Pin Name Function
1 Vin(+) Positive input voltage
2 ON/OFF Logic control input to turn converter on/off
3 Vin(–) Negative input
5 Vout(–) Negative output
6 Vout(+) Positive output
Product # SQ60120QPA28 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2SQ612J Rev. G 03/29/11 Page 3
Technical Specification
Input:
36-75V
Output:
12V
Current:
28A
Package:
Quarter-brick
Electrical Characteristics
SQ60120QPA28 Electrical Characteristics
Ta = 25°C, airow rate = 300 LFM, Vin = 48Vdc unless otherwise noted; full operating temperature range is -40°C to +100°C ambient temperature with
appropriate power derating. Specications subject to change without notice.
Parameter Min. Typ. Max. Units Notes & Conditions
ABSOLUTE MAXIMUM RATINGS
Input Voltage
Non-Operating 0 100 V Continuous
Operating 36 48 75 V Continuous
Operating Transient Protection 100 V 100 ms transient, square wave
Isolation Voltage
Input to Output 2250 V
Operating Temperature -40 100 °C
Storage Temperature -55 125 °C
Voltage at ON/OFF input pin -2 18 V
INPUT CHARACTERISTICS
Operating Input Voltage Range 36 48 75 V
Input Under-Voltage Lockout
Turn-On Voltage Threshold 31 34.5 V
Turn-Off Voltage Threshold 27.6 32 V
Lockout Voltage Hysteresis 2 4 V
Input Over-Voltage Shutdown V
Turn-On Voltage Threshold 95 V
Turn-Off Voltage Threshold 105 V
Maximum Input Current 12 A
No-Load Input Current 130 mA
Disabled Input Current 8.5 mA
Input Reected-Ripple Current 7.5 15 mA RMS through 10µH inductor
Input Terminal-Ripple Current 600 1000 mA RMS, full load
Recommended Input Fuse (see Note 1) 15 A Fast blow external fuse recommended
Recommended External Input Capacitance 47 µF Typical ESR 0.1-0.2 Ω
Input Filter Component Values (L\C) 0.47\6.6 µH\µF Internal values; see Figure E
OUTPUT CHARACTERISTICS
Output Voltage Set Point 12.46 12.5 12.54 V
Output Voltage Regulation
Over Line +0.15\-1.25 V
Over Load +0\-0.6 V
Over Temperature ±300 mV
Total Output Voltage Range 10.6 12.8 V Over sample, line, load, temperature & life
Output Voltage Ripple and Noise 20 MHz bandwidth; see Note 2
Peak-to-Peak 150 300 mV Full load
RMS 40 100 mV Full load
Operating Output Current Range 0 28 A Subject to thermal derating
Output DC Current-Limit Inception 35 A Output voltage 10% Low
Output DC Current-Limit Shutdown Voltage 10.5 V
Back-Drive Current Limit while Disabled 50 mA Negative current drawn from output
Maximum Output Capacitance 3,000 µF Vout nominal at full load (resistive load)
DYNAMIC CHARACTERISTICS
Output Voltage during Load Current Transient
Step Change in Output Current (0.1 A/µs) 1500 2500 mV 50% to 75% to 50% Iout max
Settling Time 250 350 µs To within 1% Vout nom
Turn-On Transient
Turn-On Time 12 24 ms Full load, Vout=90% nom.
Start-Up Inhibit Time 200 ms -40 °C to +125 °C; Figure F
Output Voltage Overshoot 0 % 3 mF load capacitance
Input:
36-75V
Output:
12V
Current:
28A
Package:
Quarter-brick
Product # SQ60120QPA28 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2SQ612J Rev. G 03/29/11 Page 4
Technical Specification
Input:
36-75V
Output:
12V
Current:
28A
Package:
Quarter-brick
SQ60120QPA28 Electrical Characteristics (continued)
Ta = 25°C, airow rate = 300 LFM, Vin = 48Vdc unless otherwise noted; full operating temperature range is -40°C to +100°C ambient temperature with
appropriate power derating. Specications subject to change without notice.
Parameter Min. Typ. Max. Units Notes & Conditions
ISOLATION CHARACTERISTICS
Isolation Voltage (dielectric strength) 2250V See Absolute Maximum Ratings
Isolation Resistance 30 MΩ
Isolation Capacitance (input to output) 470 pF See Note 3
TEMPERATURE LIMITS FOR POWER DERATING CURVES
Semiconductor Junction Temperature 125 °C Package rated to 150 °C
Board Temperature 125 °C UL rated max operating temp 130 °C
Transformer Temperature 125 °C
EFFICIENCY
100% Load 95 %
50% Load 95 %
FEATURE CHARACTERISTICS
Switching Frequency 260 300 275 kHz
ON/OFF Control (Option P)
Off-State Voltage -1 0.8 V
On-State Voltage 2.4 18 V
ON/OFF Controll (Option N)
Off-State Voltage 2.4 18 V
On-State Voltage -1 0.8 V
ON/OFF Control (Either Option) Application notes Figures A & B
Pull-Up Voltage 5.0 V
Pull-Up Resistance 124 kΩ
Output Over-Voltage Protection 16 V Over full temp range; no load
Over-Temperature Shutdown OTP Trip Point 140 150 °C Average PCB Temperature
Over-Temperature Shutdown Restart Hysteresis 10 °C
RELIABILITY CHARACTERISTICS
Calculated MTBF (Telcordia) TR-NWT-000332 2.6 106 Hrs. 80% load, 200LFM, 40 °C Ta
Calculated MTBF (MIL-217) MIL-HDBK-217F 2.1 106 Hrs. 80% load, 200LFM, 40 °C Ta
Field Demonstrated MTBF TBD 106 Hrs. See our website for details
Note 1: UL’s product certication tests were carried out using 15A fast blow fuse. Fuse interruption characteristics have to be taken into account
while designing input traces. User should ensure that Input trace is capable of withstanding fault currents
Note 2: For applications requiring reduced output voltage ripple and noise, consult SynQor applications support (e-mail: support@synqor.com)
Note 3: Isolation capacitance can be added external to the module.
Product # SQ60120QPA28 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2SQ612J Rev. G 03/29/11 Page 5
Technical Specification
Input:
36-75V
Output:
12V
Current:
28A
Package:
Quarter-brick
Standards & Qualifications
Standards Compliance & Qualification Testing
Parameter Notes & Conditions
STANDARDS COMPLIANCE
UL 60950-1:2007 Basic insulation
EN60950-1/A11:2009/A1:2010
CAN/CSA-C22.2 No. 60950-1:2007
IEC 61000-4-2 ESD test, 8 kV - NP, 15 kV air - NP (Normal Performance)
Note: An external input fuse must always be used to meet these safety requirements. Contact SynQor for ofcial safety certicates on new
releases or download from the SynQor website.
Parameter # Units Test Conditions
QUALIFICATION TESTING
Life Test 32 95% rated Vin and load, units at derating point, 1000 hours
Vibration 5 10-55 Hz sweep, 0.060" total excursion, 1 min./sweep, 120 sweeps for 3 axis
Mechanical Shock 5 100g minimum, 2 drops in x, y and z axis
Temperature Cycling 10 -40 °C to 100 °C, unit temp. ramp 15 °C/min., 500 cycles
Power/Thermal Cycling 5 Toperating = min to max, Vin = min to max, full load, 100 cycles
Design Marginality 5 Tmin-10 °C to Tmax+10 °C, 5 °C steps, Vin = min to max, 0-105% load
Humidity 5 85 °C, 85% RH, 1000 hours, continuous Vin applied except 5 min/day
Solderability 15 pins MIL-STD-883, method 2003
Product # SQ60120QPA28 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2SQ612J Rev. G 03/29/11 Page 6
Technical Specification
Input:
36-75V
Output:
12V
Current:
28A
Package:
Quarter-brick
91
92
93
94
95
96
97
100 200 300 400
Air Flow (LFM)
Efficiency (%)
25 ºC
40 ºC
55 ºC
70
75
80
85
90
95
100
0 4 8 12 16 20 24 28
Load Current (A)
Efficiency (%)
36 Vin
48 Vin
75 Vin
0
5
10
15
20
25
30
0 4 8 12 16 20 24 28
Load Current (A)
Power Dissipation (W)
36 Vin
48 Vin
75 Vin
Semiconductor junction temperature is
within 1
°
C of surface temperature
Figures
7
8
9
10
11
12
13
14
0 4 8 12 16 20 24 28
Load Current (A)
Output Voltage (V)
36V
48V
75V
0
5
10
15
20
25
30
25 40 55 70 85
Ambient Air Temperature (°C)
Iout (A)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
Figure 1: Efciency at nominal output voltage vs. load current for minimum,
nominal, and maximum input voltage at 25°C.
Figure 2: Power dissipation at nominal output voltage vs. load current for
minimum, nominal, and maximum input voltage at 25°C.
Figure 3: Efciency at nominal output voltage and 60% rated power vs. airow
rate for ambient air temperatures of 25°C, 40°C, and 55°C (nominal input
voltage).
Figure 4: Power dissipation at nominal output voltage and 60 % rated power
vs. airow rate for ambient air temperatures of 25°C, 40°C, and 55°C (nominal
input voltage).
Figure 5: Maximum output power-derating curve vs. ambient air temperature for
airow rates of 100 LFM through 400 LFM with air owing from pin 3 to pin 1
(nominal input voltage).
Figure 6: Thermal plot of converter at 23.3 A load current (279.6 W) with 55°C
air owing at the rate of 200 LFM. Air is owing across the converter from pin 3
to pin 1 (nominal input voltage).
Input:
36-75V
Output:
12V
Current:
28A
Package:
Quarter-brick
Product # SQ60120QPA28 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2SQ612J Rev. G 03/29/11 Page 7
Technical Specification
Input:
36-75V
Output:
12V
Current:
28A
Package:
Quarter-brick
0
5
10
15
20
25
30
25 40 55 70 85
Ambient Air Temperature (oC)
IOUT (A)
400
300
200
100
Figure 7: Maximum output power derating curves vs. ambient air temperature
for airow rates of 100 LFM through 400 LFM with air owing across the
converter from output to input (nominal input voltage).
Figure 8: Thermal plot of converter at 21.9 A load current (262.8 W) with 55°C
air owing at the rate of 200 LFM. Air is owing across the converter from
output to input (nominal input voltage).
Figure 9: Turn-on transient at half load (resistive load) (2 ms/div). Load cap: 3
mF output capacitance. Input voltage pre-applied. Ch 1: Vout (5 V/div), Ch 2:
ON/OFF input (2 V/div).
Figure 10: Turn-on transient at zero load (2 ms/div). Load cap: 3 mF output
capacitance. Ch 1: Vout (5 V/div), Ch 2: ON/OFF input (2 V/div).
Figure 11: Output voltage response to step-change in load current (50%-75%-
50% of Iout(max); dI/dt = 0.1A/µs). Load cap: 100µF, 100 mΩ ESR tantalum
cap and 1µF ceramic cap. Ch 1: Vout (2 V/div), Ch 2: Iout (10A/div).
Input:
36-75V
Output:
12V
Current:
28A
Package:
Quarter-brick
Input:
36-75V
Output:
12V
Current:
28A
Package:
Quarter-brick
Product # SQ60120QPA28 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2SQ612J Rev. G 03/29/11 Page 8
Technical Specification
Input:
36-75V
Output:
12V
Current:
28A
Package:
Quarter-brick
0
2
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40 45
Load Current (A)
Output Voltage (V)
36 Vin
48 Vin
75 Vin
10µH
source
impedance
Input
Terminal
Ripple
Current
Input
Reflected
Ripple
Current Output
Voltage
Ripple
1
µ
F
ceramic
capacitor
15
µ
F,
450m
Ω
ESR
tantalum
capacitor
47
µ
F,
<1
Ω
ESR
electrolytic
capacitor
VSOURCE
VOUT
iSiC
Converter
DC-DC
Figure 12: Test set-up diagram showing measurement pints for Input Terminal
Ripple Current (Figure 13), Input Reected Ripple current (Figure 14) and
Output Voltage Ripple (Figure 15).
Figure 13: Input Terminal Ripple Current, ic, at full rated output current and
nominal input voltage with 5 µH source impedance and 47µF electrolytic
capacitor (500 mA/div). See Figure 12.
Figure 14: Input reected ripple current, is, through a 5 µH source inductor,
using a 47µF electrolytic input capacitor (10 mA/div). See Figure 12.
Figure 15: Output voltage ripple at nominal input voltage and rated load current
(50 mV/div). Load capacitance: 1µF ceramic capacitor and 15µF tantalum
capacitor. Bandwidth: 20 MHz. See Figure 12.
Figure 16: Output voltage vs. load current showing typical current limit curves
and converter shutdown points.
Figure 17: Load current (10 A/div) as a function of time when the converter
attempts to turn on into a 1 mΩ short circuit. Top trace (500 us/div) is an
expansion of the on-time portion of the bottom trace.
Input:
36-75V
Output:
12V
Current:
28A
Package:
Quarter-brick
Input:
36-75V
Output:
12V
Current:
28A
Package:
Quarter-brick
Input:
36-75V
Output:
12V
Current:
28A
Package:
Quarter-brick
Product # SQ60120QPA28 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2SQ612J Rev. G 03/29/11 Page 9
Technical Specification
Input:
36-75V
Output:
12V
Current:
28A
Package:
Quarter-brick
-40
-30
-20
-10
0
10 100 1,000 10,000 100,000 1,000,000
Hz
Reverse Transmission (dB)
36 V
48 V
75 V
0.1
1
10
100
1000
10 100 1,000 10,000 100,000 1,000,000
Hz
Input Impedance (ohms)
36 V
48 V
75 V
0.01
0.1
1
10 100 1,000 10,000 100,000 1,000,000
Hz
Output Impedance (ohms)
36V
48V
75V
-60
-50
-40
-30
-20
-10
0
10 100 1,000 10,000 100,000 1,000,000
Hz
Forward Transmission (dB)
36V
48V
75V
Figure 18: Magnitude of incremental output impedance (Zout = Vout/Iout) for
minimum, nominal, and maximum input voltage at full rated power.
Figure 19: Magnitude of incremental forward transmission (FT = Vout/Vin) for
minimum, nominal, and maximum input voltage at full rated power.
Figure 20: Magnitude of incremental reverse transmission (RT = Iin/Iout) for
minimum, nominal, and maximum input voltage at full rated power.
Figure 21: Magnitude of incremental input impedance (Zin = Vin/Iin) for
minimum, nominal, and maximum input voltage at full rated power.
Product # SQ60120QPA28 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2SQ612J Rev. G 03/29/11 Page 10
Technical
Specification
SQ60120QPA28
Application Section
Application Section
BASIC OPERATION AND FEATURES
With voltages dropping and currents rising, the economics
of an Intermediate Bus Architecture (IBA) are becoming
more attractive, especially in systems requiring multiple
low voltages. IBA systems separate the role of isolation and
voltage scaling from regulation and sensing. The BusQor
series bus converter provides isolation and a coarse voltage
step down in one compact module, leaving regulation to
simpler, less expensive non-isolated converters.
In Figure A below, the BusQor module provides the isolation
stage of the IBA system. The isolated bus then distributes
power to the non-isolated buck regulators to generate the
required voltage levels at the point of load. In this case, the
bucks are represented with SynQor’s NiQor series of non-
isolated dc-dc converters. In many applications requiring
multiple low voltage outputs, signicant savings can be
achieved in board space and overall system costs.
When designing an IBA system with bus converters, the
designer can select from a variety of bus voltages. While
there is no universally ideal bus voltage, most designs
employ one of the following: 12V, 9V, 7.5V, 5V, or 3.3V.
Higher bus voltages can lead to lower efciency for the buck
regulators but are more efcient for the bus converter and
provide lower board level distribution current. Lower bus
voltages offer the opposite trade offs.
SynQor’s SQ BusQor modules accept the full 48/60V
telecom bus voltage and have a narrow output voltage
range compatible with many non-isolated point of load
converters. When used in IBA systems, the output variation
of the BusQor must be in accordance with the input voltage
range of the non-isolated converters being employed.
BusQor
Converter
NiQor
Converters Loads
48Vdc
Front End
Typical User Board
3.3V
CONTROL FEATURES
REMOTE ON/OFF (Pin 2): The ON/OFF input, Pin 2,
permits the user to control when the converter is on or off.
This input is referenced to the return terminal of the input
bus, Vin(-). There are two versions of the converter that
differ by the sense of the logic used for the ON/OFF input.
In the positive logic version, the ON/OFF input is active
high (meaning that a high turns the converter on). In the
negative logic version, the ON/OFF signal is active low
(meaning that a low turns the converter on). Figure B is a
detailed look of the internal ON/OFF circuitry.
TTL
ON/OFF
Vin(_)
Vin(
+
)
2.5V
1.8V
1.5V
0.9V
12Vdc
48Vdc
36-75V
Figure A: Example of Intermediate Bus Architecture using BusQor bus converter
and NiQor non-isolated converters
5V
+5V
124k
49.9k
100k
Figure B: Internal ON/OFF pin circuitry
Protection Features
Input Under-Voltage Lockout: The converter is designed
to turn off when the input voltage is too low, helping avoid
an input system instability problem, described in more detail
in the application note titled “Input System Instability”
available on www.SynQor.com. The lockout circuitry is a
comparator with DC hysteresis. When the input voltage is
rising, it must exceed the typical Turn-On Voltage Threshold
value (listed on the specication page) before the converter
will turn on. Once the converter is on, the input voltage
must fall below the typical Turn-Off Voltage Threshold value
before the converter will turn off. Also see g E.
Output Current Limit: The output of the BusQor module
is electronically protected against output overloads. When
an overload current greater than the “DC Current-Limit
Inception” specication is drawn from the output, the
output of the BusQor will shutdown to zero volts after the
1 ms have elapsed (see Figure C). The shutdown period
lasts for a typical period of 200ms (Figure D) after which the
BusQor tries to power up again. If the overload persists, the
output voltage will go through repeated cycles of shutdown
and restart with a duty cycle of 20ms (On) and 200ms (Off)
respectively. The BusQor module returns (auto resetting)
to normal operation once the overload is removed. The
BusQor is designed to survive in this mode indenitely
without damage and without human intervention.
Output
Current
Output
Voltage
<12V
0V Time
Shutdown
Period
Duty
Cycle
Peak
55A
peak
5V
+5V
124k
49.9k
100k
Output Short Circuit Protection: When the output of
the BusQor module is shorted, a peak current of typically
55A will ow into the short circuit for a time of about
1ms. The output of the BusQor will shutdown to zero volts
after the 1ms have elapsed (Fig C & D). The shutdown
period lasts for a time of 200ms, at the end of which the
BusQor module tries to power up again. If the short circuit
persists, the output voltage will go through repeated cycles
of shutdown and restart with a duty cycle of 20ms (On)
and 200ms (Off) respectively. The BusQor module returns
(auto resetting) to normal operation once the short circuit is
removed. The converter is designed to survive in this mode
indenitely without damage without human intervention.
In the Auto resetting mode, also referred to as “Hiccup”
mode, the power drawn from the 48V input is about 5W,
most of which is dissipated into the external fault. It is
important that copper traces and pads from the output
circuit be designed to withstand the short term peaks,
although the average current into the fault may be as low
as 50mA typical. See Figure 17 for appropriate waveform.
Over-Temperature Shutdown: A temperature sensor
on the converter senses the average temperature of the
module. The thermal shutdown circuit is designed to turn
the converter off when the temperature at the sensed
location reaches the Over-Temperature Shutdown value.
It will allow the converter to turn on again when the
temperature of the sensed location falls by the amount of
the Over-Temperature Shutdown Restart Hysteresis value.
Output
Current
Output
Voltage
0V
Time
35A
28A
12V
1ms
Figure C: Output Overload protection diagram (not to scale)
<12V
200ms 20ms
Figure D: Output Short Circuit and Auto-Resetting protection diagram (not to scale)
Product # SQ60120QPA28 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2SQ612J Rev. G 03/29/11 Page 11
Technical
Specification
SQ60120QPA28
Application Section
Protection Features
Input Under-Voltage Lockout: The converter is designed
to turn off when the input voltage is too low, helping avoid
an input system instability problem, described in more detail
in the application note titled “Input System Instability”
available on www.SynQor.com. The lockout circuitry is a
comparator with DC hysteresis. When the input voltage is
rising, it must exceed the typical Turn-On Voltage Threshold
value (listed on the specication page) before the converter
will turn on. Once the converter is on, the input voltage
must fall below the typical Turn-Off Voltage Threshold value
before the converter will turn off. Also see g E.
Output Current Limit: The output of the BusQor module
is electronically protected against output overloads. When
an overload current greater than the “DC Current-Limit
Inception” specication is drawn from the output, the
output of the BusQor will shutdown to zero volts after the
1 ms have elapsed (see Figure C). The shutdown period
lasts for a typical period of 200ms (Figure D) after which the
BusQor tries to power up again. If the overload persists, the
output voltage will go through repeated cycles of shutdown
and restart with a duty cycle of 20ms (On) and 200ms (Off)
respectively. The BusQor module returns (auto resetting)
to normal operation once the overload is removed. The
BusQor is designed to survive in this mode indenitely
without damage and without human intervention.
Output
Current
Output
Voltage
<12V
0V Time
Shutdown
Period
Duty
Cycle
Peak
55A
peak
5V
+5V
124k
49.9k
100k
Output Short Circuit Protection: When the output of
the BusQor module is shorted, a peak current of typically
55A will ow into the short circuit for a time of about
1ms. The output of the BusQor will shutdown to zero volts
after the 1ms have elapsed (Fig C & D). The shutdown
period lasts for a time of 200ms, at the end of which the
BusQor module tries to power up again. If the short circuit
persists, the output voltage will go through repeated cycles
of shutdown and restart with a duty cycle of 20ms (On)
and 200ms (Off) respectively. The BusQor module returns
(auto resetting) to normal operation once the short circuit is
removed. The converter is designed to survive in this mode
indenitely without damage without human intervention.
In the Auto resetting mode, also referred to as “Hiccup”
mode, the power drawn from the 48V input is about 5W,
most of which is dissipated into the external fault. It is
important that copper traces and pads from the output
circuit be designed to withstand the short term peaks,
although the average current into the fault may be as low
as 50mA typical. See Figure 17 for appropriate waveform.
Over-Temperature Shutdown: A temperature sensor
on the converter senses the average temperature of the
module. The thermal shutdown circuit is designed to turn
the converter off when the temperature at the sensed
location reaches the Over-Temperature Shutdown value.
It will allow the converter to turn on again when the
temperature of the sensed location falls by the amount of
the Over-Temperature Shutdown Restart Hysteresis value.
Output
Current
Output
Voltage
0V
Time
35A
28A
12V
1ms
Figure C: Output Overload protection diagram (not to scale)
<12V
200ms 20ms
Figure D: Output Short Circuit and Auto-Resetting protection diagram (not to scale)
55A
peak
200ms 20ms
APPLICATION CONSIDERATIONS
Startup Inhibit Period: Figure E details the Start-Up
Inhibit Period for the BusQor module when Vin is applied
with the On/Off pin asserted (enabled). Before time t1,
when the input voltage Off pin asserted (enabled). Before
time t1, when the input voltage is below the UVL threshold,
the unit is disabled by the Input Under-Voltage Lockout
feature. When the input voltage rises above the UVL
threshold, the Input Under-Voltage Lockout is released, and
a typical Startup Inhibit Period of 8ms from a Vin start-up.
Once the module recognizes it should be on it waits an
additional 4ms before it starts. When starting from an on/
off event the module has an inhibit time of 200ms like our
standard products. The output builds up to 90% or higher
of the nominal voltage and stabilizes to its nominal output
voltage in a total time of 8ms typical.
At time t2, when the On/Off pin is de-asserted (disabled),
the BusQor module stops switching immediately. Fall time
from 12V to 0V is dependent on output capacitance load
current, and any parasitic trace inductance in the output
load circuit.
At time t3, when the On/Off pin is re-asserted (enabled),
the BusQor module output begins to build up after the
inhibit period of 200ms typical.
Refer to the Control Features section of the data sheet for
details on enabling and disabling methods for N and P logic
type modules.
Vin
UVLO
On/Off
(N logic)
OFF
O N
t0
Vout
Fault Inhibit
Start-up
Inhibit
tt1t2t3
Time
Start-Up
12V
12ms 200ms
8ms
Figure E: Power Up/Down Diagram (not to scale) showing Start-Up Inhibit Period.
Product # SQ60120QPA28 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2SQ612J Rev. G 03/29/11 Page 12
Technical
Specification
SQ60120QPA28
Application Section
55A
peak
200ms 20ms
APPLICATION CONSIDERATIONS
Startup Inhibit Period: Figure E details the Start-Up
Inhibit Period for the BusQor module when Vin is applied
with the On/Off pin asserted (enabled). Before time t1,
when the input voltage Off pin asserted (enabled). Before
time t1, when the input voltage is below the UVL threshold,
the unit is disabled by the Input Under-Voltage Lockout
feature. When the input voltage rises above the UVL
threshold, the Input Under-Voltage Lockout is released, and
a typical Startup Inhibit Period of 8ms from a Vin start-up.
Once the module recognizes it should be on it waits an
additional 4ms before it starts. When starting from an on/
off event the module has an inhibit time of 200ms like our
standard products. The output builds up to 90% or higher
of the nominal voltage and stabilizes to its nominal output
voltage in a total time of 8ms typical.
At time t2, when the On/Off pin is de-asserted (disabled),
the BusQor module stops switching immediately. Fall time
from 12V to 0V is dependent on output capacitance load
current, and any parasitic trace inductance in the output
load circuit.
At time t3, when the On/Off pin is re-asserted (enabled),
the BusQor module output begins to build up after the
inhibit period of 200ms typical.
Refer to the Control Features section of the data sheet for
details on enabling and disabling methods for N and P logic
type modules.
Vin
UVLO
On/Off
(N logic)
OFF
O N
t0
Vout
Fault Inhibit
Start-up
Inhibit
tt1t2t3
Time
Start-Up
12V
12ms 200ms
8ms
Figure E: Power Up/Down Diagram (not to scale) showing Start-Up Inhibit Period.
Droop Characteristics with Voltage Mismatch
-4.0%
-3.5%
-3.0%
-2.5%
-2.0%
-1.5%
-1.0%
-0.5%
0.0%
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Load Current (% of Rated Value)
Output Voltage Droop (% of Nominal)
Unit A Unit B
Droop Characteristics with Temperature Mismatch (Self Balancing)
-4.00%
-3.50%
-3.00%
-2.50%
-2.00%
-1.50%
-1.00%
-0.50%
0.00%
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Load Current (% of Rated Value)
Output Voltage Droop (% of Nominal)
Unit A (cooler) Unit B (hotter)
12V
12ms 200ms
8ms
Figure E: Power Up/Down Diagram (not to scale) showing Start-Up Inhibit Period.
Droop Current Sharing:
This product has primary side regulation only. Primary side
regulation results in a voltage droop as the load current
increase (droop characteristic). The inherent impedance
of the power stage due to its droop characteristic can be
used to balance the load current between multiple modules
that are placed in parallel. The graphs in this section show
two units by way of example, but there is no fundamental
limit to the number of units that can be placed in parallel.
When multiple units having droop characteristics are placed
in parallel, the current sharing accuracy is determined by the
output voltage set point accuracy relative to the total output
voltage droop for a given load current range. A difference
in voltage between two units will cause a differential current
to ow out of one unit and into the other. Figure F shows an
example with two units with an output voltage mismatched by
0.5%. In this example, when Unit A is at 100% of its full rated
load current, Unit B is only at ~88%, effectively reducing the
total available current by 6%. SynQor uses factory calibration
of each unit to ensure that output voltage is well matched.
Temperature Mismatch Self Balancing: the slope of
the output voltage droop characteristic of semi regulated
module increases with increased temperature. Therefore,
if a paralleled unit were hotter than its neighbor because it
is supplying more load current, then its output voltage will
droop further forcing the cooler module(s) to increase its
load current. The increase in effective output resistance
due to an increase in temperature acts as a self correcting
mechanism (Fig G) when two or more modules are connected
in a parallel conguration.
Figure F: Example of Droop Characteristic with Output Voltage Mismatch. Figure G: Droop Characteristic with Temperature Mismatch (self balancing)
Product # SQ60120QPA28 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2SQ612J Rev. G 03/29/11 Page 13
Technical
Specification
SQ60120QPA28
Application Section
Droop Characteristics with Voltage Mismatch
-4.0%
-3.5%
-3.0%
-2.5%
-2.0%
-1.5%
-1.0%
-0.5%
0.0%
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Load Current (% of Rated Value)
Output Voltage Droop (% of Nominal)
Unit A Unit B
Droop Characteristics with Temperature Mismatch (Self Balancing)
-4.00%
-3.50%
-3.00%
-2.50%
-2.00%
-1.50%
-1.00%
-0.50%
0.00%
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Load Current (% of Rated Value)
Output Voltage Droop (% of Nominal)
Unit A (cooler) Unit B (hotter)
12V
12ms 200ms
8ms
Figure E: Power Up/Down Diagram (not to scale) showing Start-Up Inhibit Period.
Droop Current Sharing:
This product has primary side regulation only. Primary side
regulation results in a voltage droop as the load current
increase (droop characteristic). The inherent impedance
of the power stage due to its droop characteristic can be
used to balance the load current between multiple modules
that are placed in parallel. The graphs in this section show
two units by way of example, but there is no fundamental
limit to the number of units that can be placed in parallel.
When multiple units having droop characteristics are placed
in parallel, the current sharing accuracy is determined by the
output voltage set point accuracy relative to the total output
voltage droop for a given load current range. A difference
in voltage between two units will cause a differential current
to ow out of one unit and into the other. Figure F shows an
example with two units with an output voltage mismatched by
0.5%. In this example, when Unit A is at 100% of its full rated
load current, Unit B is only at ~88%, effectively reducing the
total available current by 6%. SynQor uses factory calibration
of each unit to ensure that output voltage is well matched.
Temperature Mismatch Self Balancing: the slope of
the output voltage droop characteristic of semi regulated
module increases with increased temperature. Therefore,
if a paralleled unit were hotter than its neighbor because it
is supplying more load current, then its output voltage will
droop further forcing the cooler module(s) to increase its
load current. The increase in effective output resistance
due to an increase in temperature acts as a self correcting
mechanism (Fig G) when two or more modules are connected
in a parallel conguration.
Figure F: Example of Droop Characteristic with Output Voltage Mismatch. Figure G: Droop Characteristic with Temperature Mismatch (self balancing)
Product # SQ60120QPA28 Phone 1-888-567-9596 www.synqor.com Doc.# 005-2SQ612J Rev. G 03/29/11 Page 14
Technical
Specification
SQ60120QPA28
Ordering Information
Part Numbering System
The part numbering system for SynQor’s dc-dc converters follows the format
shown in the example below.
The first 12 characters comprise the base part number and the last 3
characters indicate available options. The “-G” suffix indicates 6/6 RoHS
compliance.
Application Notes
A variety of application notes and technical white papers can be downloaded
in pdf format from our website.
RoHS Compliance: The EU led RoHS (Restriction of Hazardous
Substances) Directive bans the use of Lead, Cadmium, Hexavalent
Chromium, Mercury, Polybrominated Biphenyls (PBB), and Polybrominated
Diphenyl Ether (PBDE) in Electrical and Electronic Equipment. This SynQor
product is 6/6 RoHS compliant. For more information please refer to
SynQor’s RoHS addendum available at our RoHS Compliance / Lead Free
Initiative web page or e-mail us at rohs@synqor.com.
Ordering Information
The tables below show the valid model numbers and ordering options for
converters in this product family. When ordering SynQor converters, please
ensure that you use the complete 15 character part number consisting of
the 12 character base part number and the additional characters for options.
Add “-G” to the model number for 6/6 RoHS compliance.
The following options must be included in place of the
w x y z
spaces in the
model numbers listed above.
Not all combinations make valid part numbers, please contact SynQor for
availability. See the Product Summary web page for more options.
Warranty
SynQor offers a three (3) year limited warranty. Complete warranty
information 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.
Product Family
Package Size
Performance Level
Thermal Design
Output Current
6/6 RoHS
Options (see
Ordering Information)
Input Voltage
Output Voltage
Contact SynQor for further information:
Phone: 978-849-0600
Toll Free: 888-567-9596
Fax: 978-849-0602
E-mail: power@synqor.com
Web:
www.synqor.com
Address: 155 Swanson Road
Boxborough, MA 01719
USA
SQ 60 120 Q P A 28 N R S - G
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
Model Number Input
Voltage
Output
Voltage
Max Output
Current
SQ60120QPw28xyz-G 36-75V 12V 28A
Options Description: w x y z
Thermal Design Enable Logic Pin Style Feature Set
A - Open Frame N - Negative
P - Positive
K - 0.110"
N - 0.145"
R - 0.180"
Y - 0.250"
S - Standard
