Product Support FAQs
Are SynQor converters footprint and pin compatible with Power-One and Tyco (Lucent)
Yes, SynQor offers the same footprint and pin out configuration of the Power-One
and Tyco/Lucent half-brick, quarter-brick and eighth-brick converters.
What type of thermal relief should I use?
In general, to provide improved solderability, customers will want to add thermal
reliefs to the output pins of the converter. The design of these thermal reliefs
should be carefully considered to prevent heating due to resistive power losses.
SynQor has written a white paper
on this subject entitled "Thermal and Reliability Study." In general the aspect
ratio of the conductive paths of the thermal relief spokes should be wider than
they are long, to reduce their resistance. A significant fraction of the resistance
between the converter and the load is the first few centimeters of copper from the
output pins and the power / ground plane. Reductions in output resistance can be
made by placing a copper pad on every layer of the PCB around each of the output
pins. Place 8 to 12 vias surrounding the output pins, tying all the additional copper
pads to the power and ground planes. These suggestions will limit the resistance
(and power dissipation) in the board and increase the reliability of the plated
What can you tell me about sockets for PCB-mounted SynQor products?
SynQor generally recommends that our board-mounted products be soldered into the
system application board, as this makes the most reliable and highest performing
electrical and thermal connection for deployed products.
For system prototypes and
temporary testing, sockets are a convenient way of connecting converters to test
boards and fixtures, and SynQor does provide evaluation boards with socketed connections.
It is important to keep in mind that sockets are a poor thermal connection between
a converter or similar product and the host printed circuit board (PCB), which can
compromise the thermal performance of converters, particularly open-frame converters.
This problem is further exacerbated by the fact that the socket connection has significant
electrical resistance that causes additional heat to be dissipated. For accurate
thermal evaluation, it is important to solder the pins to the host PCB, particularly
when evaluating open-frame converters.
If the shippable system design requires the
use of sockets for assembly or maintenance, then we recommend that the socket be
of a type that uses tin-plated contacts having sufficient contact normal force to
make and maintain a gas-tight electrical connection. The system design should also
limit movement of the pin-socket interface during thermal cycling or vibration conditions
in the product service environment to prevent tin-fretting corrosion.
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What is the best strategy to minimize EMI?
There is no one perfect EMI strategy for all applications, but some basic thought
before-hand can make the task much easier. The first step is to make sure that the
location of components minimizes noise. For example, de-coupling capacitors should
be located as close as possible to the converter, especially X-caps and Y-caps.
Use ground planes to minimize radiated coupling, minimize the cross sectional area
of sensitive nodes, minimize the cross sectional area of high current nodes that
may radiate such as those from common mode capacitors. The location of the EMI components
is critical; avoid placing the converter in close proximity to your filter to avoid
noise coupling back into the filter. Keep in mind that you are not just filtering
the power supply, but all the circuitry that the converter is powering as well.
Most of today's communication cabinets employ as much local filtering as possible
at the card level, and then another filter at the power entry module, where the
power feeds will enter your cabinet. SynQor has an EMI
application note entitled EMI Characteristics that further details these
principles and includes recommendations for 1 and 2 stage filters that are designed
around SynQor's converters. Please contact SynQor directly
for design assistance, or email
What type of conducted line filter should I use?
While a pre-designed EMI filter may be adequate for a particular converter, there
is no guarantee that it will suppress other sources of conducted EMI that are present
on your board, such as the noise from high-speed processors and other digital logic
devices. Better value and performance will be obtained with a discrete filter design.
The key to a smooth EMI compliance process is to design as much filtering as possible
onto your circuit pack. This will allow the flexibility to tweak and modify components
when the initial testing is performed. It is best to over-design up front than be
caught off guard; components can easily be deleted once the initial testing is completed.
Adding components to an existing PCB design is much more difficult and can yield
unpredictable results. SynQor has suggested one and two stage filters that are simple
and reliable to implement, and for much less cost than an off-the-shelf filter.
These suggested filter circuits are in SynQor's EMI
Application note. In general most modern communications equipment uses a
local EMI filter on each of the circuit cards, and a final shielded filter located
in or near the power entry module.
How do I choose Y-Caps?
Y-caps are the EMI capacitors that are connected from the input power feeds to chassis
ground. Sometimes they are connected from each converter's power output terminal
to chassis ground as well. SynQor filter designs use 2700pF Y-Caps. The voltage
rating depends on the insulation and isolation safety rating of the -48VDC supply.
If you are unsure of these attributes, use capacitors rated to 2000V. If the -48V
is a reinforced insulation scheme, then 100V rated capacitors will suffice.
What does the input filter of your converter look like?
All SynQor half bricks use a C-L-C input filter. All SynQor quarter bricks and eighth
bricks have an L-C filter. The value of these components can be found in SynQor's
EMI application note, or in the appropriate
What if I don't have a chassis ground?
While it is preferable to have and to use a chassis ground, it is not mandatory.
Under some circumstances a chassis ground will not be available for the input conducted
EMI filter. If this is the case, you will want to use a different filter topology.
for this circuit.
What type of filter should I use for multiple converters?
For multiple converters, you can still use SynQor's recommended filter design, just
be sure to size the individual components to handle the maximum current at the lowest
I currently have my input and output filtering arranged for a different manufacturer's
converter. Will your module work with this filtering or must it be changed?
In general, a filter that has been previously designed around a 200 to 500KHz fixed
frequency converter will be adequate for an equivalent SynQor converter. SynQor's
converters have lower common mode noise due to their lack of a baseplate. Baseplated
units have higher common mode noise as the switching noise of the power semiconductor's
couples through the parasitic capacitance of the baseplate.
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Are there any special concerns with an open frame converter?
SynQor open frame converters are no worse, and often better, than baseplated converters.
In general most baseplated units have a plastic cover, and in 3 Meter and 10 Meter
far field measurements offer no advantage compared to the SynQor open frame design.
SynQor's unique topology and reduced common mode noise have a significant advantage
over other manufacturers' converters in regards to reducing radiated emissions.
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How will an open frame converter perform versus a baseplated converter?
With few exceptions, most customers have found the near-field characteristics of
SynQor's open frame converters to be no worse, and often better than the typical
baseplated converter. SynQor has several suggestions for reducing near-field radiation-
the first of which is to place a ground shield beneath the converter. SynQor suggests
placing a primary referenced ground shield beneath the converter's primary circuitry,
and a secondary referenced ground shield beneath the converter's secondary side
circuitry. The isolation barrier on all SynQor converters is easily found by looking
for the 1.4mm clearance gap located on both the top and bottom of the PCB, or by
locating the optoisolators, which also identify the barrier. (Note: All of SynQor's
magnetic assemblies are considered primary referenced.) With regard to the near-field
EMI above the typical baseplated converter, a baseplate is not a perfect "shield"
as commonly thought. Unfortunately the baseplate is tightly coupled to the converter's
high frequency switching nodes (in particular, the drains of the primary-side MOSFETs).
The shield is therefore "bouncing" and attempts to stop it from doing
so by grounding it to the output are challenging. Typically the circuit path to
ground is hindered by the parasitic inductance of the PCB connection. As such, the
baseplate is not well-grounded at high frequencies, and radiates significant noise.
There are also still the sides of the module to contend with, as these are not generally
shielded. If there is sensitive circuitry, it is best not to place it directly over
a converter or close to the edges of the converter unless it has a ground shield
directly over or under the conduction path, as this will reduce any coupling. It
is also helpful to note that the amount of noise that can be coupled is proportional
to the cross sectional area of the conduction path; the smaller the loop, the less
noise that will couple.
What about other Parasitic Baseplate Effects?
If you could hold the baseplate quiet by grounding through a low inductance path,
the result would be a great deal of common-mode current that would flow from the
primary side switching nodes to the baseplate (through parasitic capacitors) and
to the output ground. This then creates other problems that need to be addressed,
mainly conducted common mode noise. Common mode noise tends to be a challenging
problem to control. SynQor's converter design eliminates this problem as it has
very little parasitic capacitance to the output ground. What noise it does have
is effectively controlled with a common mode capacitor that we place on our converter.
Compared to the industry standard Class B conducted noise filter, you will find
that the SynQor converter needs half as many filter stages due to the reduced common
mode noise. Also see SynQor's EMI Application
What about magnetic fields?
Baseplated converters will offer improved protection from near B-field radiation.
At most frequencies, a baseplated converter will be approximately 10dB/uM more quiet
than the open frame design. If B-field noise is a critical design consideration,
any SynQor converter can be ordered with an optional baseplate, which will offer
the same reduction in B-field noise.
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Enable Circuits/Inrush Control
Why do I need an inrush controller?
All converters act as negative resistors, and all power distribution paths have
some inductance. These two elements require that some electrolytic capacitance be
placed across a converter's input terminals to compensate for the negative resistance,
preventing a possible oscillation. If a circuit card containing a converter is hot
swapped into a back plane, the charging of the electrolytic capacitor can cause
a low voltage transient or glitch on the 48V supply, which could upset other circuits
sharing the common 48V feed. To prevent this glitch on the input rail, an inrush
control circuit should be placed in series with the 48V feed. An inrush control
circuit limits the charging of the 48V rail. A good example of a controller for
an inrush circuit is Linear Technology's LT1640 and LT1641, Summit Micro's SMH4804,
or Supertex's HV300 series.
How do I select an inrush controller?
You can drive the enable of a DC-DC converter with the inrush controller's power
good or enable signal provided there is no EMI filter between the controller's ground
reference and the converter's ground reference. If there is an EMI filter located
between the inrush controller and the enable circuit, the noise which the EMI filter
rejects will appear on the enable lines, and could cause the modules to turn on
and off randomly depending upon the size of the injected noise. The inrush controller
and the converter must have the same reference. This can be avoided by leaving the
modules permanently enabled, not using the Power Good signal, moving the common
mode filter to come before the hot swap circuit, or adding some isolation between
the Power Good output and the input to the modules (such as an optocoupler).
Why is there a 200ms delay at turn on for your new family of converters?
Most all of SynQor's converters have a 200ms startup delay at initial turn on, and
after a fault condition such as OVP or Over Temperature Shutdown. After recovering
from any fault condition, the converter will not turn on for 200ms. When the bus
voltage is below the under voltage lockout, this is considered a fault condition.
This behavior is detailed in our data sheets, and should be studied before implementing
an inrush or sequencing strategy. The delay ensures that the start up behavior is
always consistent and well controlled. If the input voltage were to glitch momentarily
to zero volts, then return to the full bus voltage, the delay gives the control
circuitry time to return to proper startup conditions. Since the control circuitry
has no voltage when the input voltage is brought to zero, it is difficult to distinguish
between power up after a glitch and initial power up. Therefore, the module treats
all recoveries from undervoltage lockout identically. The delay on power up also
guarantees that the input voltage is well within the operating range before powering
up the output load. Note that after the delay time has passed, the module will turn
on quickly when the ON/OFF pin is set to the enabled state.
How do I sequence multiple converters?
Sequencing requirements need to be considered in the preliminary stages of the power
supply design. Usually these requirements are driven by ASICs or processors, which
have separate Core and I/O voltages. Often these voltage rails must turn on in a
specific order (sequence) or are required to have no more than some maximum voltage
difference between these rails. If this maximum difference is violated, the chip
can be damaged or even destroyed. In general there are three (3) ways to sequence
the turn on characteristics of multiple converters.
The first method is to turn the converters on in a specific sequence with either
a control chip such as Summit Micro's SMH4804, or with discrete circuitry. A simple
solution is to have the output of one converter drive an optoisolator that enables
the second converter, and so on. In general most sequencing requirements will want
the lowest voltage to turn on first, and off last. It is important to use an optoisolator
to enable the other converter as the enable is a primary referenced signal, while
the output of a converter is a low voltage isolated SELV signal.
Another method often used is to tie diodes between the different voltage rails in
a manner that while powering up the diodes will conduct, but when the converter
outputs are fully on, the diodes are reversed biased. For example a diode between
the 5V rail and the 3.3V rail, with the cathode connected to the 5V rail, will force
the 5V rail to follow the 3.3V rail while turning on, but once the 5V rail is at
5V, the diode will be reversed biased. This forces the difference in voltage between
the two rails to be no more than one diode drop apart. Conversely, 3 diodes with
a 0.7V drop in series from the 5V rail towards the 3.3V rail will ensure that the
3.3V rail is charged should it come up after the 5V rail.
The last and most complex solution is to place FETs in series with each converter's
output, and enabling the FETs once the converters are fully turned on. By carefully
controlling the turn on of the FET gates, the voltage rails can be brought up in
strict adherence to any sequencing specification. Such a solution can be built with
discrete components or by using a specific controller such as Summit Micro's SMT4004.
One note of caution when implementing these solutions: if the sense lines are connected
on the output side of the MOSFETs, the converter will not be able to sense its output
voltage at turn on until the MOSFETs are on. This will cause the converter to raise
its output until it reaches over voltage protection. You must either connect the
sense lines directly to the converters output and trim up to compensate for the
FETs on resistance, or add additional FETs to connect the sense lines after the
main FETs are enabled.
Any suggestions on using Summit Micro's hot swap controllers?
It is important when defining a system's sequencing requirement that SynQor's 200ms
initialization period be considered. As an example, if you are using a programmable
delay to enable multiple converters in a specific sequence, you must make sure the
delay is approximately 200ms. When using the Summit Micro devices, make sure to
use their 160ms delay setting, and use the second delay tap to enable the first
converter. As an example for a three converter solution you use the SMH4804 where
PG#2 would enable the first converter, PG#3 for the second and so on.
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How do I choose an input electrolytic capacitor (input E-cap)?
SynQor has written an application note
on how to select an input electrolytic capacitor and why this capacitor is needed.
The paper can be downloaded from the Application Notes page of our website. In general
you will find that each converter will require a capacitor that is approximately
47uF to 100uF with a minimum voltage rating of 100VDC, and an ESR in the range of
0.5 to 1 Ohm.
How do I choose a CM Inductor?
Select an inductor that is rated for the desired input current. Leakage inductance
in the common mode inductor will provide reduction of differential mode input current
ripple. SynQor's recommended conducted EMI filters specify a primary inductance
of 360uH (0.36mH) and a leakage inductance of 3.5uH. A popular choice for these
inductors are Pulse Engineering's Self-Leaded SMT Common Mode Chokes, such as P/N
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Can I create negative voltages with SynQor converters?
All of SynQor's converters are fully isolated which allows them to generate negative
output voltages. Simply connect the Vout+ terminal to the system output ground,
and a negative voltage will be generated on the Vout- terminal.
I have a negative 48V bus. Can I use SynQor converters?
Because the converter is isolated, the Vin+ terminal can be tied to the input ground
of a -48V system. The Vin- terminal should then be connected to the -48V rail. Keep
in mind that the primary side signal pins are referenced to the Vin- terminal in
How do I read the codes on the product label?
Each product has a label which reveals the product part number, revision letter
code and serial number for that module. This information can be found on the label
in the specific locations detailed in
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Where do I find the safety certifications?
All of SynQor's safety certificates can be found
Where are the conditions of acceptability?
All safety certifications, including the conditions of acceptability can be downloaded
in PDF form here.
How do I choose a fuse?
The Conditions Of Acceptability (COA) section of the safety file details the type
of fuse required for each converter. SynQor's product datasheets specify the recommended
fast blow external fuse to be used.
What is creepage and clearance?
Safety certification requires that the primary 48V circuitry (Primary) and the low
voltage output (Secondary) circuitry be separated from each other. SynQor's converters
use a Basic level of insulation, with 2000V of isolation. As such, all SynQor converters
have a minimum distance of 1.4mm between primary and secondary circuitry.
What is "insulation rating" and "isolation rating"?
Insulation refers to the design parameters used to isolate the 48V primary side
signals from the low voltage secondary side signals. This covers the specifications
for creepage and clearance between traces and components, as well as the type of
insulation used in the transformers. The transformers transfer energy between the
primary (Input) and secondary (Output) stages of the converter. All SynQor converters
use Basic Insulation which meets the most stringent requirements for 48V based DC
systems. Isolation refers to the breakdown rating of the isolation stage, either
in the transformer or between isolated components such as optoisolators. SynQor
tests and guarantees all converters capable of withstanding a 2000V breakdown.
Are any dangerous voltages exposed on the surface of the converter?
In the United States, UL defines an "Unsafe" voltage as 60V, this is called
the SELV (Safety Extra Low Voltage) limit. At input voltages of 0 to 60V, the highest
voltage will be across the midbuss capacitors, this is an AC signal, operating at
the switching frequency, with a maximum peak to peak amplitude of about 58V. Above
a DC input of 60V the maximum voltage is the input voltage across the primary switching
FETS, which is approximately Vin plus a few volts.
Are safety covers recommended for the converters or is a "danger high voltage"
or similar label required on the surface of the converters?
If the input voltage remains below 60VDC, then all voltages are SELV, and no special
care is needed. If the input voltage rises above 60VDC, then there will be non SELV
voltages on the top side of the converter. The exact need for warning labels or
covers, depends on the safety agency approvals needed. For UL, If non-technicians
are to be allowed to change system configurations, i.e add more memory cards, the
machine should be powered off to prevent access to the non-SELV voltages.
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How do I reduce output noise and ripple?
In general SynQor's converters have significantly lower output noise and ripple
when compared to traditional isolated converters. This is due to SynQor's patented
power topology, and excellent design practices. All of SynQor's ripple and noise
measurements defined in our data sheets are made with
10uF of Tantalum and 1uF of Ceramic capacitance across the converter's output. This
is not required, but is used so that our converter's measurements conform to standard
industry practices. Further reduction of output ripple and noise is accomplished
through the addition of both Tantalum and Ceramic capacitance. Ceramic capacitance
provides attenuation of output ripple, while the inherent ESR of tantalum capacitors
provides damping. It is possible to provide additional filtering through the use
of LC filters, but care should be taken when placing these filters within the sense
lines, as this can effect the converter's stability. Consult the factory for further
support on this topic.
What is SynQor's crossover frequency and phase margin?
All SynQor converters are designed to have adequate stability margin (at least 20dB
of gain margin, and 50 Degrees phase margin) over variations of input and output
conditions, including input voltage range, output voltage range, output current
range, and load impedance. Performance is verified by using Bode plots and examining
gain and phase margin.
How much output capacitance can I drive with your converter?
All SynQor data sheets define the maximum allowable startup
capacitance with a fully loaded output. If the output load current at startup is
reduced, then a larger amount of capacitance than defined in the
data sheet is possible. An interesting benefit of SynQor's topology is that
a large amount of output capacitance has little effect on the converter's stability!
How do you trim a converter?
All SynQor converters have a trim pin, which allows trimming the nominal output
voltage higher and lower. In general, to trim a converter low, a resistor is connected
from the trim pin to the -Sense pin. To trim up, connect a resistor from the trim
pin to the +Sense pin. The value for the resistor is calculated with the formulas
provided in the converter's data sheets. You can also use the Trim Resistor Calculator
found in the Application Notes section.
The trim formulas match accepted industry standards for half, quarter and eighth
Can I trim a converter actively?
Trimming or margining converters with an external active circuit is possible and
SynQor has several sample circuits available depending on your requirements. Please
consult your local SynQor representative, or email
How does Over Voltage Protection (OVP) work; does it track the trim?
SynQor's OVP protection is fixed and does not track the output voltage when using
the trim function. Customers should use care when trimming the converter to ensure
the OVP is not activated during transient conditions, or when series diodes or FETs
are used on the converter's output. On SynQor's first generation half brick converters
containing HNA in the part number, the OVP protection is measured across the sense
lines. Care should be taken to ensure that the output pins do not become disconnected
from the sense lines. If the output pins become disconnected, and there is some
capacitance across the sense lines, damage could occur to the converter's output
stage. This could happen if the output pins are not properly soldered, or if MOSFET's
are placed in series with the output. On SynQor's new Kilo, Mega, Giga, and Tera
half bricks, as well as the QNA/QGA quarter bricks, the OVP sense point is located
across the output pins which avoids this condition.
Can I put converters in series?
SynQor's converters can be placed in series, however should one converter turn off,
a protection mechanism should be implemented to ensure that the other converter
What are sense lines? Do I need to connect them?
Sense lines are used to compensate for resistive drops along the power distribution
path. The sense lines should be connected at the point of load, or at a minimum
connected to the output pins at the converter. If the sense lines are not connected,
the regulation and set point specifications contained in the
data sheet will not be met. No damage will occur if the sense lines are
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Full Feature Converters
What is the OR-FET signal used for?
The primary function of the full feature converters OR-FET signal is to supply a
voltage source higher than the converter's output voltage which can provide current
to turn on the gate of an N-Channel "ORing" MOSFET. The signal has no
implied "intelligence". ORing FETs are used to isolate the output of a
converter in the event that the converter's output experiences a short fault. This
is preferable to "ORing" diodes that have significant power losses at
high output currents. This signal is very low power, and is not capable of supplying
more than 50mW of power. Any control circuitry drawing beyond 50mW of power should
be driven off the converter's main output.
The OR-FET pin can also be used as a Power Good signal: when the converter is operating
properly the OR-FET voltage will be much higher than the converters output, providing
a positive indicator of a converter's health even in a system where converters are
directly connected in parallel.
More details are available in our Full Feature
Can I use the Cshare pin as an output current monitor?
The current share pin will give a voltage that is proportional to the output current,
but only for a single module. If two converters are sharing a common load by using
the current share connection the voltage will represent the average current of the
two converters. This signal is referenced to the primary side of the converter,
so to interface with a controller the signal will have to be brought across the
isolation barrier through an optoisolator (unless of course the controller is on
the primary side, then a direct interface is possible.) Any load impedance added
to the CSHARE signal should be above 100kOhms. Loading on this signal will affect
the current sharing performance. More details are available in our Full Feature
How do I synchronize modules?
SynQor Full Feature converters have a pin to provide synchronization with an external
clock. The signal should be a 5V TTL level rectangular wave with a duty cycle between
25% and 75%. The CSYNC signal is referenced to the Vin- pin of the converter. When
synchronizing different output voltage converters, you should select the highest
frequency specified for any converter as the common frequency. Converters will not
synchronize properly at frequencies below that specified in their datasheet. More
details are available in our Full Feature
Should I synchronize modules?
While Synchronizing converters may make EMI characterization and filter design simpler,
it can also cause converter harmonics to stack on top of each other, creating a
more difficult EMI problem to solve. Generally EMI specifications require measurements
be quasi-peak, and it is more beneficial to leave the converters not synchronized.
Certain systems require synchronization so that the output ripple is at a single
frequency. Applications such as wireless communications equipment, systems with
extremely fast clocks, or sensitive optical circuits may find that the benefits
of synchronizing the converters output ripple outweigh the EMI benefits of having
un-synchronized converters. More details are available in our Full Feature
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Can I parallel converters for more power?
SynQor's family of Kilo, Mega, Giga, Tera and some Peta half bricks can be ordered
with the full feature set which allows converters to be paralleled for more power,
as well as to take advantage of additional control features.
How do I connect SynQor's full feature converters in parallel?
To connect full feature modules in parallel, you simply connect the current share
pins and the start sync pins of the sharing converters together. In addition, make
sure that the Vin+ and the Vin- pins are tied together, as the Vin- pins provide
a common reference for the current share signal. Outputs should be connected together
at a common point with the sense lines. SynQor has an application schematic detailing
these connections. Please refer to the Full Feature
Application Note for this schematic.
How do I trim converters in parallel?
A trim circuit should be supplied for each individual converter, therefore each
converter should have a trim resistor. Make sure that all trim resistors are the
Where do I connect the sense lines for parallel converters?
The sense lines of converters in parallel should be connected together at the exact
same point for balanced transient responses and the best output voltage regulation.
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How should I store and handle open frame converters?
Open frame converters can be damaged from poor handling, excessive mechanical shock,
or from a static electric discharge. The units should be:
- Carefully handled and not subjected to mechanical stresses
- Treated as an ESD sensitive component
- Stored in a static protective container which physically protects
- The converters should not be stored in plastic bags, or stacked
on top of one another in any way
Are SynQor's converters water wash compatible?
SynQor converters are compatible with a water wash process, provided that the converters
are dry before powering them on. SynQor uses a no clean flux, and as such the flux
residue on our converter may react with other chemicals from the manufacturing or
wash process. Generally this manifests itself as a white powder residue on the converter.
This is usually benign, but any such residue should be analyzed to confirm its reactivity.
Customers using an active detergent in the water wash process may need to apply
a piece of kapton tape over the SynQor label to prevent the label from fading.
What type of flux do you use?
SynQor uses flux systems that meet or exceed Telcordia GR-78 CORE SIR and Electromigration
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What is SynQor's MTBF?
SynQor's standard reliability measure is Mean Time Between Failure (MTBF) measured
in hours of time. SynQor uses the Military Standard MIL217-F to calculate MTBF based
on ambient temperature and load. SynQor's standard calculations are for 48V nominal
input, 300LFM, and 80% load at 25C, 40C, and 55C. SynQor can also calculate MTBF
using the Tellcordia (Formerly Bellcore) Parts Count Method TR332. In addition,
SynQor also measures the actual field reliability in MTBF or FIT by product family.
To request any of this reliability information please submit a request to your local SynQor sales representative, or email
. Some MTBF is also presented in the product datasheets.
What are common failure modes?
The most common failure mode for units returned by our customers is NFF, or "No
Fault Found". To prevent the return of NFFs through SynQor's RMA process, SynQor
has evaluation boards available so customers can test the operation of the converter
before returning them. The evaluation boards allow for simple testing and debugging.
What is SynQor's qualification process?
SynQor has a three-step release process: POD, POM, and Qualification. POD, or Proof
Of Design, is the process during which the converter's performance is evaluated
and characterized over all rated operating conditions and beyond, in accordance
with HALT principles. POD measures component stresses to ensure that design guidelines
are met and that no components are over-stressed in both normal and abnormal conditions.
POD ensures that long-term reliability and life targets are achieved. Other tests
performed at the POD stage include phase and stability margins, thermal margin,
capacitive load tests, destructive thermal cycling, DFM, and waveform analysis.
POM, or Proof Of Manufacturing, ensures that SynQor has designed a part that can
be manufactured, is reliable, and has proper margins to be run in a high volume
factory. POM ensures that target yields are met, that our ATE systems are optimized,
and any new manufacturing equipment or processes constructed are optimized. SPC
analysis at this stage is mandatory, and CPKs are scrutinized to ensure that SynQor
has a repeatable and consistent process.
Qualification is the final stage of product release. The purpose of the qualification
process is to ensure that SynQor has designed and built a product that exceeds our
customers' expectations. Testing at this stage includes aggressive thermal shock
cycles, extended high temperature life and humidity tests, vibration and mechanical
shock tests in accordance with military standards, terminal solderability, full
mechanical and dimensional compliance, as well as a thorough examination of the
solder and manufacturing quality.
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How do I measure output ripple?
Measuring output ripple and noise is extremely dependent on the test setup. A good
starting point for this is to use SynQor's Evaluation Board which can be purchased
from SynQor. Our evaluation board provides a BNC connector for measuring output
ripple. The industry standard noise measurement requires 20MHz bandwidth limit which
is detailed in our data sheets. There is also an
application note titled, "Output Voltage Ripple Measurements,"
which provides proper methodology and test set-ups to achieve accurate output ripple
readings whether you are using our evaluation board or an application board.
This paper also describes how using a traditional probe with a ground clip will
allow radiated noise to couple into the probe creating a false measurement, which
manifests as large high frequency spikes. These are largely measurement artifacts
which are most often caused by two effects: magnetic coupling through a large scope
ground loop, and/or transmission line effects on unterminated cables. SynQor's application note on this topic will
show you how to reduce the measurement circuit loop to a minimum, almost eliminating
magnetic noise pickup and allowing a more accurate measurement of the converter's
output voltage ripple.
How do I measure Output Load Current?
You can easily measure the output load current of any SynQor open frame converter.
The application note Output Load
Current Calculations outlines the equations and other information needed to make
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How do I choose a heatsink?
Choosing a heatsink requires knowing several things:
- The output power required.
- The power dissipated by the converter at the load current and input
- The worst case ambient temperature.
- The amount of airflow available.
- The maximum baseplate temperature of the converter, which is 100C
for all SynQor baseplated converters.
What size heatsink is required for 3.3V quarterbrick at 20A, 48V input, 70C ambient,
and 200LFM of airflow?
Using SynQor's PQ48033QGA25 data sheet figure 3, at 48V input, and with a 20A load,
the power dissipated by the SynQor's 3.3V quarterbrick converter is about 8.5 Watts.
The allowable temperature rise is simply the maximum baseplate temperature minus
the worst case ambient temperature. So in this example, 100C - 70C = 30C allowable
rise. The thermal impedance of the heatsink required is simply the allowable temperature
rise, divided by the power dissipated. In our example this is 30C/8.5Watts, giving
a maximum thermal impedance requirement for our heatsink of 3.53C/W at 200LFM. Using
any standard heatsink catalog you can now select a heatsink. A good choice would
be Intricast's (www.intricast.com)
HS1361XM01 heatsink, which is 0.5" tall and has a thermal impedance of 2.60 C/W
How do I measure the temperature on your converters? Where do I place thermocouples?
SynQor's derating curves are created based on a derating of 125C for switching MOSFETs.
Using SynQor's data sheet, locate the thermal image,
which shows the hottest components on the power supply. Generally you will want
to measure the input MOSFETs, the isolation stage MOSFETs, and the output synchronous
rectifiers. Care should be taken not to block too much of a device's surface area,
as this could significantly reduce its ability to remove heat via convection.
How does SynQor's thermal protection work, and where is the sensor?
On SynQor half bricks, a thermistor located on the topside of the PCB drives a comparator
circuit. On the quarter brick converters there is an integrated temperature sensor
that will trip the converter off if an over-temperature condition exists. Both methods
work by sensing the PCB temperature. Email
for location details.
Do you have flotherm models?
SynQor has basic thermal models that can be used for customers to develop flotherm
models, but due to the use of multiple power handling devices to spread the heat
generation across the board, it is very difficult to provide a detailed thermal
model of the open frame converter.
What is the optimal orientation of the converter?
In general, half bricks are less sensitive to orientation than quarter bricks. For
half brick converters 2.5V and below, it is best to have the air flowing towards
the output terminals, for half bricks 3.3V and above it is better to have the airflow
towards the input side of the converter. On quarter bricks and eighth bricks, it
is always best to make the airflow perpendicular to the long side of the converter
as this exposes the maximum surface area to a cooling airflow. Although the differences
are minor, it is best practice to review the derating curves and thermal images
found in the data sheets to determine optimal orientation.
What is the difference in air speed measurements of CFM vs. LFM?
Designers often need air speed measurements to calculate thermal derating and power
dissipation for their DC-DC converters and for their overall systems. There are
two basic units of measure: CFM (cubic feet/minute) is a measurement of volume,
LFM (linear feet/minute) is a measurement of velocity. Fan manufacturers use CFM
because they rate their fans according to the quantity of air they can move. Velocity
(speed) is more meaningful to heat removal at the board level. This is what most
DC-DC converter manufacturers will specify when calculating thermal derating curves
and other performance specifications. To convert CFM measurements to LFM, use the
LFM = CFM/AREA
LFM = Linear feet per minute of airflow
CFM = Cubic feet per minute of air volume
AREA = the area of the opening in square feet.
For example, let's assume you are blowing air through a 6" x 6" opening across the
top of a DC-DC converter with a 100CFM, unobstructed fan.
LFM = 100/ 0.25 sq feet or about 400LFM calculated.
The most accurate way to measure actual air speed is with an anemometer.
Some manufacturers specify airflow in Linear Meters/Second. Use the table below
to convert feet/minute into meters/second:
100 f/m = 0.5 m/s
200 f/m = 1.0 m/s
300 f/m = 1.5 m/s
400 f/m = 2.0 m/s
500 f/m = 2.5 m/s
How do I attach heatsinks?
Use M3 screws with a length no longer than 0.125". Tighten the screws to a
torque of 6.0 in-lb. Minimum screw length is 0.10" for adequate hold. For more
details, please refer to the appropriate data sheet addendum
for baseplated modules, located in the products section.
What type of potting material do you use?
In the baseplated versions of its modules, SynQor uses a proprietary potting material.
Contact your local SynQor representative, or email
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