Imaging Mass Spectrometry


Imaging mass spectrometry (IMS) is providing a useful tool for the analysis and study of tissue samples. New machines are now capable of reviewing hundreds to thousands of molecules in one tissue section simultaneously. The TDK-Lambda medically certified SWS1000L-48 power supply is now being used by a leading manufacturer of IMS machines, chosen for its proven performance across the medical industry and for local sales and technical support.


Static Phase Converters

PFE series AC-DC power module

When only a single phase AC voltage is available and a load is a three phase motor, a static phase converter is used to provide power to initially start the motor. Once running, the static converter is disconnected and the motor continues to operate off the single phase. Two of TDK-Lambda’s baseplate cooled power modules, the 28V output PFE500SA-28 and the 360V output PF1000A-360, are being used in static phase converters for railway stations. Technical support and cost effectiveness were the primary reasons for the selection.


Pulse Electron Deposition


The Pulsed Electron Deposition (PED) technique enables thin films of materials to be deposited on substrates for semiconductor manufacturing. This method is now being used as an alternative to Pulsed Laser Deposition, with the benefit of lower system costs. The 20kV output ALE-202A power supply, with a 2200 J/s peak charging rate, was chosen for this application because of its excellent pulse to pulse repeatability and TDK-Lambda’s, and three 7,500W TX plug in power supplies.

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How do I select an external EMI filter for use with a power supply?

Although most power supplies have an internal EMI filter, there are situations where an additional system filter is needed to comply with regulations. Power supplies are tested for the manufacturer by certification laboratories in optimum, repeatable conditions. Input and output cabling is well separated, and resistors used to load the product.

In reality, system space constraints for cabling, loads with fast switching microprocessors and/or the use of more than one power supply (EMI noise is additive) can generate additional noise. In this case an additional EMI filter may be needed.

Let us consider an application using TDK-Lambda’s SWS1000L-24 1000W power supply, and that the system will be operated on world-wide AC inputs of 115 or 230V.

The first parameter to consider is the input voltage. Common input voltage ratings are 250Vac or dc, 500Vac or dc (three phase) or 75Vdc. Note – a 250Vac filter can be used with 115Vac inputs. For the SWS1000L power supply, then we will need a filter rated at 250VAC.

The current rating should then be determined. The power supply datasheet should state maximum input current, or alternatively on the rating label. The rating label for the SWS1000L-24 power supply is shown below. Note that the input current shown is for a worse case of 100Vac input and accounts for the power supply inefficiency and power factor. Never assume that a 1000W power supply will only draw 10A at 100Vac input!

SWS1000L rating labelSWS1000L-24 Rating Label

If the power supply is to be used only with a 230Vac input, then the filter rating can be reduced to approximately half. That information will provided on the datasheet.

Continuing with our SWS1000L-24 example, we will need a filter rated at a minimum of 16A to give us a 20% safety margin, as it is not good practice to operate parts at their maximum rating. Running a filter above its rated value, even for short periods, can cause the internal inductors to saturate and become ineffective.

From TDK-Lambda’s website selector guide the RSEN2016 looks suitable. Looking at the derating curve for 50oC ambient, we are within the specification.

Fig 2RSEN2016 Derating Curve

To see how effective the filter is, we then need to look at the attenuation characteristics on the datasheet.

Fig 3RSEN2016 Attenuation vs Frequency Characteristics

From the evaluation data on the SWS1000L-24 we can see what the EMI performance of the unit is. We can then check if the filter has a good insertion loss at any of the frequencies we want to reduce further, in this case 1-10MHz.

Fig 4SWS1000L-24 conducted EMI plot

As the SWS1000L series has medical safety certifications, earth leakage current may be a consideration. The low leakage RSEN2016L should be used, as the RSEN2016 has 1mA leakage, compared to the L version’s 0.01mA.

Attenuation of the RSEN2016L is still good for the application.

Fig 5RSEN2016L Attenuation vs Frequency Characteristics

Further options are available for the TDK-Lambda R series if more attenuation is required. The RSHN2016L is a two stage filter with better performance (0.1mA leakage current).

Fig 6RSHN2016L Attenuation vs Frequency Characteristics

If input transients are a concern, the RSMN2016 or RSMN2016L filters feature a two stage filter design with an amorphous core to clamp any high voltages surges.

If it is desired to mount the filter on a DIN rail, then any of the above models can be ordered with a DIN rail clip, for example RSHN2016LD.

When taking a system to an external test house, TDK-Lambda advises bringing a selection of different performance filters. This avoids having to reschedule with the test house (at extra cost), and also minimise the filter cost. TDK-Lambda Technical Support can also assist with your design and give advice on cable routing and noise suppression

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Selecting a line filter to reduce input transients

In addition to EMI (Electro Magnetic Interference) reduction, some EMC line filters are able to provide protection against input transients. These external influences can come from a number of sources and their energy level (measured in Joules) varies accordingly.

High frequency noise is usually generated by power supplies and motor drives. The voltage level is small and the energy level minimal – only several mJ. This can be easily handled by a standard EMI/EMC filter.

Impulsive noise is generated from relay switching or induction motors. Voltages can be in the thousands of Volts with an energy level of hundreds of mJs, significant enough to cause problems with a power supply. Although the IEC 61000-4-4 standard covers product immunity to electrical fast transient voltages on the input lines, the test limits for this are only +/-2kV. For more noisy environments, a filter containing additional protection is recommended.

Surge noise is caused by lightning, and can have significant energy content. The voltage is very high, in the 10s of kVs. This level of energy is best clamped using special lightning arresters.

Fig 1

TDK-Lambda uses amorphous cores to reduce impulsive noise spikes, rather than metal oxide varistors (MOVs) or voltage dependent resistors (VDRs). MOVs clamp spikes, but degrade over time following multiple line surges. Amorphous cores are made from very thin (μm) ferromagnetic amorphous metal strips wound to form a doughnut shaped core, and do not degrade.

Although the ferrite cores used in most EMI/EMC filters do reduce the amplitude of voltage spikes, they can saturate and cause a significant decrease in attenuation.

Shown below is a comparison between a ferrite core and an amorphous core, and the test method used. It can be seen that the amorphous core out performs the ferrite core.

Fig 2

Fig 3

TDK-Lambda’s R series filters that have amorphous cores for high voltage pulsed noise prevention can be found in this selector guide.

Models include:
RSAL 250VAC 0.5 to 6A General purpose
RSAN 250VAC 3 to 60A General purpose
RSMN 250VAC 3 to 60A Two stage filter for better performance
RTAN 500VAC 3 phase 6 to 60A General purpose
RTMN 500VAC 3 phase 6 to 60A Two stage filter for better performance

Power supply failure analysis reports often include independent laboratory test reports that state “component over voltage stress”. The reaction of the recipient is often one of disbelief, claiming that at the time of failure there was no abnormal AC line activity.

Without appropriate protection, input surges can damage a power supply over a long time period, with the effect not seen immediately. High voltage surges will stress and damage both semiconductors and passive components alike, leading to premature failure in the field.

Using a slightly more expensive EMI/EMC filter with pulse attenuation can improve system up-time and reduce expensive service calls.

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Wide range input DC-DC converters deliver 30W in a 1 x 1 inch footprint

CCG30_24_48 PR Jun15

TDK Corporation announces the introduction of the CCG30 series of 30W DC-DC converters. Packaged in the industry standard 1 x 1 inch footprint, the CCG series can operate over a wide 4:1 input range. Enclosed in a metal case with six-sided shielding, these high performance converters are suitable for use in data and tele-communications, industrial control, test and measurement, broadcast and portable battery powered equipment.

Accepting either a 9 to 36Vdc or 18 to 76Vdc input, the CCG series can provide output voltages of 3.3, 5, 12 or 15Vdc and currents of up to 7A. Operation from 12V and 24V, or 24V and 48V nominal inputs assists with material control and inventory availability.

Measuring just 25.4 x 25.4 x 9.9mm, the high efficiency units, up to 91%, will operate in ambient temperatures of -40°C to +85°C. Standard features include +/-10% output voltage adjustment, remote on-off, over-current, and over-voltage protection. All CCG30 models carry a five-year warranty.

The CCG series is fully isolated with an input to output isolation of 1,500Vdc and 1,000Vdc input or output to case. Safety certification includes IEC/EN 60950-1, UL/CSA 60950-1 with CE marking for the Low Voltage and RoHS2 Directives.

For more information about the full range of TDK-Lambda CCG series of DC-DC converters, please call TDK-Lambda directly on +44 (0)1271 856600 or visit the TDK-Lambda website at:


Local Manufacturer helps AS-Level students qualify for CREST Gold Award

LA3875 - Image
TDK Corporation is pleased to announce that TDK-Lambda UK is continuing to support Blundell’s School AS-Level students qualify for their Engineering Education Scheme certificates and British Science Association CREST Gold awards. This award is widely recognised and respected by UCAS for university admissions in STEM subjects.

This year’s project involved establishing a method for controlling the ambient temperature for the surface mount component placement production lines and goods-in area. Previous projects included a method to calculate the facility’s carbon-footprint and developing a wind tunnel.

The five person team from Blundell’s school in Tiverton worked under the guidance of Tim Puttick, Production Manager for TDK-Lambda UK. Tim provided support and assistance to the pupils as needed. “The project team took the challenge and over a six month period produced a solution that allowed the ambient temperature of the two areas to be controlled either automatically or manually. A combination of low cost industrial materials and coding with a Raspberry Pi were utilised.”

These projects allows students to develop skills that are not usually used in a class room environment, and included project planning, writing program code, building prototypes, analysing return on investment for decision making and working as a focus team.

CREST is a UK award scheme that recognises success, enabling students to build their skills and demonstrate personal achievement in project work. It offers educators an easy-to-run framework for curriculum enhancement and is student-led, which means that young people take ownership of their projects and choose to undertake them in areas they enjoy or see as relevant. The CREST Gold award requires about 70 hours of project work and is the highest of four levels.


How does an input EMI filter work?

Most electronics contains an EMI filter, either as a separate device, or embedded in circuit boards. Its function is to reduce high frequency electronic noise that may cause interference with other devices. Regulatory standards exist in most countries that limit the amount of noise that can emitted.

EMI, or Electro-Magnetic Interference, is defined as unwanted electrical signals and can be in the form of conducted or radiated emissions. Conducted EMI is where the noise travels along the electrical conductors and radiated EMI is where the noise travels through the air as magnetic fields or radio waves.

EMI is generated from the switching of electrical current and comes from a variety of sources including electronic power supplies. Power supplies convert an input voltage into regulated and isolated (in most cases) DC voltages to run a host of electronic components. That conversion is performed at high frequencies ranging from several kHz to more than a MHz. LED lighting, computers, motor drivers, DC relays and battery chargers all rely on power supplies to operate.

An EMI filter for a power supply normally consists of passive components, including capacitors and inductors, connected together to form LC circuits. The inductor(s) allow DC or low frequency currents to pass through, while blocking the harmful unwanted high frequency currents. The capacitors provide a low impedance path to divert the high frequency noise away from the input of the filter, either back into the power supply, or into the ground connection.

Figure 1 shows a simple single stage power supply filter

Fig 1

In addition to assisting to meet EMI regulations, the filter also has to meet safety standards. The inductor temperature rise is measured and for mains operation, the minimum electrical spacing between line, neutral and ground are controlled. This reduces the risk of fire and electrical shock. The capacitors are also individually safety certified, depending on their position in the circuit. Special “X” capacitors have to be used across the input terminals and “Y” capacitors from the AC circuit to ground.

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Grounding Open Frame Power Supplies

Users of open frame power supplies are often surprised when they test a unit on the bench and measure output noise higher than the published specification. This prompts a call to Technical Support, who will then advise that the product has to be correctly grounded, or earthed.

TDK-Lambda’s open frame ZPSA60 power supply

Enclosed power supplies, like TDK-Lambda’s HWS series, have a metal chassis, and can be easily tested without any such concerns. Why is this?

If a power supply is a Class I type (needing a ground connection) input and output noise suppression usually involves ceramic capacitors between line/neutral to ground and DC output to ground. A typical connection is shown below.

On the AC input, high frequency noise flows through the low impedance path of the capacitors to the earth ground. This avoids the electrical noise being transmitted back down the AC input and causing problems with other equipment in the form of EMI (Electro-Magnetic Interference). On the DC output, the capacitors have the same function, this time avoiding high frequency noise appearing on the output of the power supply and causing problems with the load. Note in some cases there may be only one output to ground capacitor.

Looking at the (unpopulated) printed circuit board of the ZPSA60 power supply, the red arrow indicates the location of the two input side capacitors, CY2 and CY3. A copper trace connects them to the bottom left mounting hole. The blue arrow indicates the location of the output capacitor CY1, this time connected to the bottom right mounting hole.

(We can ignore the top two mounting holes as they have no connection made to them.)

When the power supply is tested on the bench, there is no earth ground connection to the power supply (just line and neutral and the output). An earth connection can be made to the bottom left mounting hole, there still is no connection between the two holes, effectively disconnecting the output noise filter capacitor(s).

Once the unit is mounted on the metal chassis of the system (with metal standoffs and screws), all the capacitors are in circuit. At this point, the power supply will operate within its specification.

Some open frame power supplies like TDK-Lambda’s ZMS100 series are capable of operating with or without an earth ground connection, and can be used within a plastic enclosure. An internal wire (indicated by the pointer) links connects the two mounting-hole points together to ensure compliance to the output noise specification.


Why power supply evaluation reports are useful

TDK-Lambda has for many years posted graphical and detailed test reports on the website. So why are they useful when the product specification gives all of the parameter limits?

  • Test methods – A specification or datasheet does not tell the reader how the product was actually tested. Where are the voltage and current meters situated? How is the output ripple and noise measured? Is the earth leakage current recorded with a regular ammeter?
  • Design margin – Often limits are described as “typical”. True test data can eliminate uncertainty (or the need to retest by the customer) and show what kind of margin the product has.
  • What really happens to the power supply during the test? – Load and line regulation changes are given for a variety of inputs and load conditions. This can be used to avoid any surprises when exporting a product to a country that operates on a different input voltage.
  • Over load – When overcurrent is specified it is quite often just stated as “>120%”. A plot will show if the power supply output current folds back, folds forward or remains constant through to a full short circuit. This helps determining cable sizes and pcb trace widths. As the current is often sensed on the primary side of the converter, seeing how the product behaves at different input voltages is also important.
  • Start-up and shutdown characteristics – This will indicate if the power supply has monotonic rise and fall times and how long the product takes to start up. Products that have glitches during start-up can cause issues with certain load types.
  • Actual hold-up times – Important if the power supply does not have active power factor correction, as hold-up times at 115Vac inputs are half those at 230Vac. It is informative to see what the hold-up performance is at different loads as some circuit topologies can have very small hold up times at light loads. Customers who need extended hold up can also review the data for a higher wattage model to see if that will meet their needs.
  • Dynamic load response – This is a good indication of how stable the power supply is. If the output voltage oscillates after a load change, then the control circuit or output filter may be marginally designed.
  • Leakage current – This data shows how the current leakage current not only changes with AC input, but also with power supply output load.
  • EMI performance – Knowing what design margin the power supply has can determine if an external filter is required. A product with a low EMI signature can result in cost savings by eliminating a system filter.

Purchasing a power supply without such detailed data can result in having to requalify another power supply if last minute issues do show up, leading to launch schedule delays and loss of revenue. For customers that do perform extensive power supply testing, it allows those tests to be simplified, again saving money.

Immunity and reliability data is also available for many models on the TDK-Lambda website: