LittelFuse’s 0456020.ER – A Family of High Performance Fuses

Placing through-hole parts is among the most expensive parts of the PCB assembly operation. Eliminating them should be a task in the life of every hardware designer. LittelFuse – the name, as always, is not a typo by the OEMsecrets crew – provide the 456 family of high performance fuses which come in a handy surface-mount case.

First of all, we must mention the obvious: if you use an SMD fuse, the assembly is no longer field repairable and must be returned to a service center for repair. This might be a problem for simple systems, but – surprisingly – usually does not cause grief as systems become complex. This is caused by the situation that extremely complex SMD assemblies cannot be repaired in the field – if the part has to go back to the lab anyways, reflowing one more package is part of the game.

LittelFuse provides a total of four different sizes of SMD fuse, all of which are outlined in our figure…

…LittelFuse offers four versions of the 0456020.ER

Surface mount fuses, traditionally, have problems with activation time. LittelFuse promises that the part can stand its rated current for at least four hours, while shutting down with in a maximum of 60 seconds if 200% of the rated current flows. Sadly, the maximum allowed voltage is rather low – depending on size, between 65 and 125V AC can be disconnected. Finally, designers working with their own PCB design software should keep in mind that the parts don’t come in traditional SMD housings. You will, instead, have to make do with the layout shown in the figure.

…These layouts are best created by hand

Infineon’s IPP60R060P7XKSA1 – What Benefits Does CoolMOS Offer?

While MOSFETs show up often in OEMsecrets search trends due to various constraints when designing switching regulators, Infineon’s IPP60R060P7XKSA1 gave us a start – Mouser still lists the part is brand-new, the CoolMOS 7 technology was introduced but a few months ago.

The C7 family differs from its predecessor in a variety of factors. Infineon – old hands might know the company is the semiconductor division of Siemens – promise that the part combines the benefits of fast junction MOSFETs with properties usually found in slower MOSFET transistor types.

As usual, the basic specs of the transistor don’t tell us particularly much – the maximum drain source voltage, commonly called Vdc, lays in the range of 600 V. The transistor can handle a drain current of up to 48 amperes of direct current. In this mode, the drain resistance lays in the range of 49 mOhms – a very small value, which lets the part handle this large amount of current.

This being OEMsecrets, we, do not end our trip through the world of transistors here. Instead, let us herd you to a somewhat hidden application note found by Clicking Here. In principle, the most significant benefit of the latest version is smaller structure size – our figure compares the P7 to its predecessor architecture.

Smaller structures improve transistor performance…

In addition to lowering the drain resistance, the newly devised topology also has the benefit of decreasing gate capacitance. This allows switching processes to take place faster, reducing the amount of power dissipated during the transitional process. Yours truly is aware of more than one case where gate capacitances caused problems – most of the heat burned in the transistors is lost during the transition.

The Infineon application note furthermore provides insight into how the IPP60R060P7XKSA1 can benefit you – if your question is related to FET transistors, simply click the link above and have an electrical engineering book in hand.

Furthermore, keep in mind that Siemens also offers additional documentation which, sadly, is a bit hard to find. Visit Here and click on the four small squares at the bottom – the four additional whitepapers provide further insight.

Texas Instruments’ TPA3125D2N – Audio Amplifier Design

Audio amplifier design is an interesting and annoying task – while some made a fortune writing books on the topic, in many cases, any amplifier is good enough. Normally, parts such as the PAM8302 get used. In practice, one often needs more power – in this case, Texas Instruments TPA3125D2N is the part to call on.

While the part comes in an easy to handle DIP package, do not let the packaging fool you. Texas Instruments uses a modern class D amplifier, and can supply either 10 or 20 watts into an eight ohm speakers when supplied with 24 V of direct current.

However, due to the high efficiency of the part, no heatsink is needed when approaching the extremely high values. From a technical point of view, the TPA3125D2N is relatively simple. Driving a speaker, in principle, is done with the following application example.

Driving a speaker with the TPA3125D2N is pretty simple…

Sadly, working with low input voltages is not a strength of the part. The lowest supply voltage Texas Instruments specifies in the data sheet is 10V – the figure shows how the output power varies across the various input voltages.

…output power depends on input voltage

Another interesting aspect involves circuitry intended to eliminate the popping sound found when connecting or disconnecting power or speakers. This is highly valuable, as it reduces potential risk of damage to the audio system.


Finally, let’s also recommend a look at the data sheet found by Clicking Here – it contains interesting additional information on power supply problems and similar issues encountered when dealing with class D amplifyers.

Vishay’s CRCW-HP e3 Family & the CRCW120647R0FKEAHP

Spikes are the bane of any and every automotive design. In many cases, they kill resistors by temporary terminal overload. Vishay’s CRCW-HP e3 family, one of which is the CRCW120647R0FKEAHP, provides designers with the tool to combat the problem.

In theory, short-term overloads should not be a problem for resistors – after the spike has gone away, the thermal capacity of the part should ensure that the total heat remains in a manageable range. Sadly, this is not the case in practice – local thermal maxima can make the part burn out either immediately or as time goes by.

Vishay’s CRCW-HP e3 family uses a ceramic substrate which is intended to provide for a more robust thermal behavior due to its ability to spread heat quickly. This means that the parts are pretty robust when it comes to dealing with spikes. Our figure, taken from the data sheet, shows how the parts handle loads as long as the amount of time which they are subjected to them remains short.

Spike duration, obviously, influences the behavior of the CRCW120647R0FKEAHP…

Policies usually go hand-in-hand with significantly increased voltages. These voltages can “jump” over the component, thereby causing significant damage downstream. Avoiding this is best done by staying below the highest voltage limits, which Vishay specifies as shown in figure 2.

Voltage resistance also depends on the duration of the spike…

One particularly interesting aspect of the CRCW-HP e3 family is the availability of various case sizes. Our table shows but a few of the possible candidates, each of which has a different maximum thermal capacity.

Case size influences component robustness…

While this might be surprising to beginners, the phenomenon can be explained easily. Keep in mind that thermal resistance is a function of the thermal mass of the part in question – if more ceramics are used, it is only logical that the component becomes more robust.

Myrra 44266 – PCB-Mountable Transformers

Even though recent failures of vintage HP test equipment have Joe Boeschert a bad name, history has all but vindicated his decision to become a pioneer of switching regulators. Their success has pushed classic transformers into the background – a significant mistake.

In many cases, transformer-based supplies can be more efficient. This is caused by multiple factors: in addition to less EMI issues, a dedicated transformer sometimes is cheaper than the various parts needed to protect the switcher.

One interesting candidate comes from Myrra…

One interesting candidate comes from Myrra – based in France and Poland, the company has a long history of building transformers. One particularly interesting part is the Myrra 44266, and is a member of their family of PCB-mountable transformers.

This is not a hallucination: the transformer comes with hold pins which allow the part to be soldered onto your PCB like any other large inductor. Due to the relatively high weight (which the manufacturer does not specify), using a cable tie or a bit of glue to securely fix the part is recommended.

When installed, the 44266 behaves just like any other transformer – it wants an input voltage of 230 volts AC, and breaks it down to a nominal voltage of 9V. The power rating of 10VA, then, allows us to deduce the maximum current handled by the transformer to be 1.111A.

…the part is certified according to UL 5085, VDE, EN 61558-2-6 and EN 60950

This part differs from its competitors by the wide amount of certifications – the part is certified according to UL 5085, VDE, EN 61558-2-6 and EN 60950. The transformer provides an insulation voltage of up to 4 kV, and promises that the secondary coil is short-circuit proof by design (an interesting document on that is found by Clicking Here. Should disaster ever since your application, the plastic case is self extinguishing according to the UL94-V0 standard.

STMicroelectronics’ VND5004B – Drive Ground-Connected Loads Without a Sweat

Be it a fan, a turbine or any other kind of inductive or resistive load – keeping an eye on safety becomes difficult if large amounts of current flow. STM’s VND5004B and VND5004BSP30 high-side drivers are a nice way to work around the problem.

Understanding the part is best accomplished by looking at figure one. It shows an example of the VND5004 being interfaced to a microcontroller of choice. The resistors next to the GPIO pins are required to prevent latch-ups of the GPIO interface, as inductive loads can wreak all kinds of havoc in your circuit during switch-off.

Interfacing the VND5004 to a microcontroller is easy…

Driving large currents – the datasheet maximum of the part is at 100A – requires both security precautions and careful PCB design. ST tries to make designer’s life easier with the pinout – figure two shows that the output pins are multiplied.

Furthermore, a pad at the bottom provides both Vcc and a first-class opportunity to attach a PCB heatsink directly to the ICs die. This, sadly, is a problem for hand assembly – if you don’t have a reflow oven in-house, pass assembly to another firm or buy one.

“Doubling” pins spreads current across the PCB…

While undervoltage shutoff, thermal and short-circuit protection are relatively simple to understand, the official datasheet of the part does not provide any information on the actual voltage levels found at the sense pins – when used with an ADC; they are intended to provide feedback on the current drawn by the load.

More answers on this topic can be found in application note AN1596, which describes both the semiconductor topology used and gives practical advice on component behavour. When driving serious inductive loads, definitely do take a look at it before finishing your circuit.

Texas Instruments’ LM4041 – When a Zener Just Doesn’t Cut it

Finding a good voltage reference is as difficult as asking a cigar afficionado for the perfect smoke – the answer depends on the mood and the character of the individual queried. TI’s LM4041 series provides a “common sense” solution for all those not desperate for the highest accuracy.

From a technical point of view, the LM4041 is but a better zener diode available in various three- and five-terminal SMD housings. This means that the responsibility for current limitation falls solely in the hands of the user – directly connecting the part to a high, unregulated DC voltage rail leads to catastrophic failure. Instead, the simplest possible approach involves a shunt regulator as shown in figure one.

…The protection resistor limits the current flowing through the reference

TI provides an adjustable version of the LM4041, which works via a set of external feedback resistors. In that case, total accuracy depends on both the resistors and the LM4041 – a situation which can become interesting as thermal drift takes place.

In general, TI promises an original accuracy of their 0.1 or 0.2% as shipped, with detailed data given on the influence of temperature changes on system performance. Sadly, TI does not specify much in terms of long-time stability: the maximum information given in the datasheet claims a 125ppm change in voltage output over 1000 hours. Nevertheless, the part – for sure – is interesting and should be at the back of your mind when working on data acquisition systems.

Vishay’s NTCS0805E3222JMT Case Resistor

NTCs and other thermosensors traditionally come in through-hole packages. Vishays NTCS0805E3222JMT is an excellent SMD part which can be placed right next to the heat source or ground plane whose temperature value you wish to monitor.

Just as in the case of most other Vishay resistors, the part number NTCS0805E3222JMT stands for but one component in an entire family of values. In our case, particularly, we are looking at 0805 case resistor with a value of 2k2 Ohms at nominal temperature. The whole family is shown in the table contained in the figure.

Vishay provides a wide range of values for this resistor…

The data sheet for the component is relatively limited in that it only explains the deviation of the B values found in the individual parts. However, excellent and wide-ranging further amount of information is available by visiting the curve computation website found at and shown in figure two.

The only issue related to the product is that it is – like most other Vishay design tools – based on VBA, and thus requires the presence of a real version of Excel. Nevertheless, Vishay’s part most definitely deserves your attention when looking for NTCs – being able to eliminate annoying and slow throughhole processes is a surefire way to bring and assembly cost down.

Vishay assists engineers when using their SMD NTC thermistors…

Takachi’s TWN4-2-6W

A frequently repeated bit of advice by the OEMsecrets crew involves looking off the beaten path. When looking for a ready-made case for your electronic trinket du jour, taking a look at the offerings of Takachi is an interesting alternative to classics such as Hammond.

Based in – you guessed it – Japan, the company has, so far, largely been focused on the domestic market, making good use of the Galapagos effect described in this video. Watch Video Here. However, Takachi recently started to branch out to Europe – the TWN4-2-6W is one extremely interesting example of the breed.

When purchased from a distributor like Farnell, you get a tiny case which is 2×3.5×6 cm in size and has a white body color. The situation, however, becomes more interesting once you look into the datasheet of the product – our Japanese case supplier provides a wide variety of different case sizes outlined in the table.

The TWN4 family is available in various sizes…

One especially interesting aspect of the product involves the availability of boots. This somewhat Japanese-English term refers to a rubber piece which can be tucked to the front and the back, giving the case both antiskid and slight antivibration properties – incidentially, Western Digital used a similar process in their external hard drives with great success.

Bringing a boot makes your case more resilient…

Using a prefabricated case makes great sense especially when you are dealing with small production volumes-keep in mind that the set up for injection molding can easily eat up $10,000. Comparing this to Takachi’s price of about three dollars when you buy 25 makes the product attractive for small series production.

Keep in mind that very small prototypes can be modified using a drill press in a fashion similar to figure 3. Alternatively, Farnell also offers a customization service for the TWN4-2-6W.

This component houses an RFID antenna…

Vishay’s TNPW Family – TNPW120614K3BEEA SMD Resistor

SMD resistors are seen as a component which “just exists”. Designers are usually not willing to give the part more attention – unless one fails or becomes unaccurate due to overheating or environmental problems.

Vishay’s TNPW family, represented here by family member TNPW120614K3BEEA, is an excellent candidate for all situations where high amounts of reliability are needed in a SMD package. The resistors most outstanding feature is its incredible insensitivity to moisture and heating. The datasheet claims that the parts keep their value even at 85°C and when confronted with a humidity of 85%.

Vishay prides itself on offering a wide variety of value and heat dissipation options, most of which are outlined in the table.

The TNPW family is available in various case sizes…

Let the OEMsecrets team share an old hint here: designing resistor values very close to the maximum allowed amount of power dissipation is a real anti-pattern. Especially when working in automotive or motor control scenarios, spikes will crop up – in many cases, using a resistor with a sufficiently large power dissipation capability is enough to neutralize them.

Finally, developers planning to use the parts in their project are well advised to contact their distributor. Vishay is willing to send lots consisting of parts in a single date code, which – in theory – should reduce the spread of the individual parts even further.

However, it is not sure whether this is even needed. Vishay claims that every single part is optimized using a laser trimming process known from traditional precision resistors. Furthermore, parts are tested on the one by one basis, which means that that promised accuracy should be met without issues.