Low Capacitance ESD Protection Diodes Micro−package Diodes for ESD Protection

The ESD7181 is designed to protect voltage sensitive components that require ultra−low capacitance from ESD and transient voltage events. Excellent clamping capability, low capacitance, low leakage, and fast response time make these parts ideal for ESD protection on designs where board space is at a premium. It has industry leading capacitance linearity over voltage making it ideal for RF applications.

 Features

• Low Capacitance 0.3 pF (Typical)

• Low Clamping Voltage

• Small Body Outline Dimensions: (0.62 x 0.32 mm) − 0201

• Low Body Height: 0.3 mm

• Working Voltage: ±18.5 V

• Low Leakage < 1 nA (Typical)

• Low Insertion Loss

• Low Dynamic Resistance: < 1 W

• IEC61000−4−2 Level 4 ESD Protection

• SZ Prefix for Automotive and Other Applications Requiring UniqueSite and Control Change Requirements; AEC−Q101 Qualified andPPAP Capable

• These Devices are Pb−Free, Halogen Free/BFR Free and are RoHSCompliantTypical Applications

• RF Signal ESD Protection

• Wireless Charger

• RF Switching, PA, and Antenna ESD Protection

• Near Field Communications

ESD Voltage Clamping

For sensitive circuit elements it is important to limit the voltage that an IC will be exposed to during an ESD event to as low a voltage as possible. The ESD clamping voltage is the voltage drop across the ESD protection diode during an ESD event per the IEC61000−4−2 waveform. Since theIEC61000−4−2 was written as a pass/fail spec for larger systems such as cell phones or laptop computers it is not clearly defined in the spec how to specify a clamping voltage at the device level. ON Semiconductor has developed a way to examine the entire voltage waveform across the ESD protection diode over the time domain of an ESD pulse in the form of an oscilloscope screenshot, which can be found on the datasheets for all ESD protection diodes. For more information on how ON Semiconductor creates these screenshots and how to interpret them please refer toAND8307/D.

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Everyday a product ：LM2940-5.0与7805的比较

   LM2940 has high conversion efficiency than the 7805. There will be 3mA current consumption (quiescent current)when 7805 without direct input connected to the output of the internal situation. LDO element quiescent current is far smaller than it.The LM2940 is a LDO (LDO means a low dropout regulator, which means higher low dropout linear regulator, as opposed to the traditional linear regulator. The traditional linear regulators, such as the 78xx series chips' input voltage are required to higher than the output voltage 2v ~ 3V at least, or it will not work properly. However, in some cases, this condition is clearly too harsh, such as 5v turn  3.3v, differential input and output is only 1.7v, apparently not satisfied with the conditions. The LDO class power conversion chip were invented only for this case.

LM2940-5.0 low dropout three-terminal regulator chip

Model: LM2940-5.0P + Package: TO-220

   Fixed output voltage low dropout three-terminal regulator; the output voltage of 5V; Output Current 1A; the output current is 1A, the minimum input-output voltage is less than 0.8V; maximum input voltage of 26V; Operating Temperature -40 ~ + 125 ℃; intron quiescent current reduction circuit, current limiting, thermal protection, and reverse battery protection circuit-insertion.

   The UTC LM2940 is a low dropout regulator designed to provide output current up to 1A with a typically 500mV dropout Voltage and a maximum of 1V. It is capable of reducing the ground current when the differential between the input voltage and the output voltage. 

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Connecting leaders in Internet of Things

Global Semiconductor and Electronics Forum 2017

Connecting leaders in Internet of Things – this is still very much the hot topic in consumer electronics and automotives. 

We had Samsung Electronics open the forum for us with a frank admission that profitability has yet to be seen from IoT, but it is early days in adoption. 

Dell shared the important role data scientists played and it is efficiency, safety and customer satisfaction that are the crucial factors driving IoT. This is essential for businesses to bring IT and operational technology to make it work. They also outlined the exponential growth of IoT and data will lead to the network infrastructure unable to cope with the current progress in the cloud even with the declining cost of data analytics, but you can sell data to other companies to profit. Ultimately it is cloud security that is the biggest concern for businesses.

We also heard from start-up wearables company, Misfit sharing the wearables 2.0 evolution beyond being the current health tracker with their goal to create elegant, customisable products and they’ve survived by doing more with less and procuring brand partnerships that have allowed them global recognition.

Whirlpool outlined their vision for the connected home and the move towards super intelligence, they see emotional interaction – human elements are added to technology.

On the automotives side, we had Qoros Auto explain the level of connectivity already offered in their cars where every 15 seconds data is uploaded to their cloud and telematics relies upon constant user engagement to provide them with different services. 60% of the value from the bought car comes from services. To Qoros, innovation needs speed, but you need to think about the design and architecture from day 1. They’re building a Qoros car community based on social, ecommerce, loyalty and fun, tapping into the 570 million active users on WeChat who can share their location for geo-targeted marketing.

However, how can you benchmark connectivity in the car? There are no industry benchmarks. So is it lifetime of services or profitability of services that companies need to focus on?

PSA Peugeot Citroën was telling us China is launching a user based insurance in 2017 in 6 cities as a pilot which will further propel the car sharing market. The car will just become another device in the IoT world for data collection. They expect cars to be fully automated by 2020 and be self-driving by 2025. The transition would see the car as a service rather than ownership. This is in line with the rise of the shared economy for pay-per-use services. Maps and navigation is a strategic resource for the autonomous car market. Tesla, the leader in connected cars, built the battery and infotainment first and is the inspiration for the industry especially as a start-up. SAIC-Alibaba have followed a similar route with AliOS in the cars, keeping customers in their ecosystem to push content.

OEMs are shifting to be more mobile, for example PSA is used for car sharing in Berlin and France and will launch in China in 2-3 years. The mindset is changing as the industry is disrupted by the internet players. They’re investing in developers, but this needs to be done cost effectively as apps are updated daily, devices change every 6 months but cars are built to last.

IoT can be seen as a risk to the automotive industry if you don’t reinvent yourselves. OEMs can only survive by using data effectively and not be just a hardware supplier.

You need to be agile, investing in start-ups because if you don’t disrupt yourself today, you’re going to be disrupted tomorrow. These disruptions are coming so OEMs are creating brands to manage that so that the value is transferred from the hardware to software.

Data ownership is still the big question but this is dependent on the contract and the location so in China for example all data is monitored by the Government. Who pays for the data? This depends on the apps that the automotive companies benefits from.

Industry standards are the biggest challenge as consumers don’t want to buy and understand all the different standards – they just want everything integrated.

BMW debated the responsibility model when it came to autonomous cars; they’re working with Baidu in China to test the autonomous car in Shanghai and advises partnerships with local Chinese internet companies to navigate the different ecosystem and legal system.

To end the day, we had GE look at what IoT meant on an industrial scale from digital wind farms to software defined machines, but ultimately industrial data storage is required.

As IoT develops, questions over standards and security will need to be answered and for 2017 this will be top of the agenda, but are there any other critical issues you want covered?

Amplifier Classes, The Classification of Amplifiers

Amplifier Classes Explained

Not all amplifiers are the same. Generally, amplifiers are classified according to their circuit configuration and method of operation, and as such Amplifier Classes are used to differentiate between them. Amplifier classes range from entirely linear operation (for use in high-fidelity signal amplification) with low efficiency, to entirely non-linear (where faithful reproduction is not so important) operation with high efficiency, while others are a compromise between the two.

Amplifier Classes are mainly lumped into two basic groups. The classically controlled conduction angle amplifier forming amplifier classes A, B, AB and C, which are defined by the length of their conduction state over some portion of the output waveform, such that the output stage transistor operation lies somewhere between being “fully-ON” and “fully-OFF”, and the so-called “switching” amplifier classes of D, E, F, G, S, T etc, that are constantly being switched between “fully-ON” and “fully-OFF”.

The most commonly available amplifier classes are those that are used as audio amplifiers , mainly A, B, AB and C and to keep it simple, it is these amplifier classes we will look at here in this amplifier classes tutorial.

Class A Amplifier

Class A Amplifiers are the simplest in design, and probably the best sounding of all the amplifier classes due to their low signal distortion. The class A amplifier has the highest linearity over the other amplifier classes and as such operates in the linear portion of the characteristics curve. This means that the output stage whether using a bipolar, mosfets or IGBT device, is never driven fully into its cut-off or saturation regions.

Class A Amplifier

To achieve high linearity and gain, the output stage is biased “ON” (conducting) all the time and operates at a constant current equal to or greater then the current which the load (usually a loudspeaker) requires to produce the largest output signal. The output device conducts through 360 degrees of the output waveform. Then the class A amplifier is equivalent to a current source.

Since a class A amplifier operates in the linear region, the transistors base (or gate) DC biasing voltage should by chosen properly to ensure correct operation and low distortion. However, as the output device is “ON” at all times, it is constantly carrying current, which represents a continuous loss of power in the amplifier.

Due to this continuous loss of power class A amplifiers create tremendous amounts of heat adding to their very low efficiency at around 30%, making them impractical for high-power amplifications. Therefore, due to the low efficiency and over heating problems of Class A amplifiers, more efficient amplifier classes have been developed.

Class B Amplifier

Class B amplifiers were invented as a solution to the efficiency and heating problems associated with the class A amplifiers. The basic class B amplifier uses two complimentary transistor devices (one NPN and one PNP transistor connected in common collector mode) in its output stage configured in a “push-pull” arrangement, with each device amplifying only half of the output waveform.

In the class B amplifier, there is no standing bias current as its quiescent current is zero, therefore its efficiency is much higher than that of the class A amplifier. When the input signal goes positive, the positive biased device conducts while the negative device is switched off. Likewise, when the input signal goes negative, the positive device switches off while the negative biased device turns on and conducts the negative portion of the signal.

Class B Amplifier

Therefore, each transistor device of the class B amplifier only conducts through 180 degrees of the output waveform in strict time alternation, but as the output stage has devices for both halves of the signal waveform the two halves are combined together to produce the full linear output waveform.

This push-pull design of amplifier is obviously more efficient than Class A, at about 50%, but the problem with the class B amplifier design is that it can create distortion at the zero-crossing point of the waveform due to the transistors dead band of input base voltages from -0.7V to +0.7V, making it unsuitable for precision amplifier applications.

Class AB Amplifier

As its name suggests, the Class AB Amplifier is a combination of the two class A and class B type amplifiers above, and is currently one of the most common types of power amplifier design. The class AB amplifier is a variation of a class B amplifier as described above, except that both devices are allowed to conduct at the same time around the crossover point eliminating the crossover distortion problems of the pure class B amplifier.

The two transistors have a very small bias voltage, typically at 5 to 10% of the quiescent current to bias the transistors just above cut-off. In this case, the transistor will be “ON” for more than half a cycle, but less than a full cycle of the input signal. Then in a class AB amplifier design each of the push-pull transistors is conducting for slightly more than the half cycle of conduction in class B, but much less than the full cycle of conduction of class A.

Class AB Amplifier

The advantage of this small bias voltage is that the crossover distortion created by the class B amplifier characteristics is overcome, without the inefficiencies of a the class A amplifier design. So the class AB amplifier is a compromise between class A and class B in terms of efficiency and linearity, with efficiencies reaching about 50% to 60%.

Class C Amplifier

The Class C Amplifier design has the greatest efficiency but the poorest linearity of the classes of amplifiers. The previous classes, A, B and AB are considered linear amplifiers, as the output signals amplitude and phase are linearly related to the input signals amplitude and phase.

However, the class C amplifier is heavily biased so that the output current is zero for more than one half of an input sinusoidal signal cycle. In other words, the conduction angle for the transistor is significantly less than 180 degrees, at around 90 to 120 degrees.

This form of biasing gives a much improved efficiency of around 80% to the amplifier, but very heavy distortion of the output signal. Therefore, class C amplifiers are not suitable for use as audio amplifiers.

Class C Amplifier

Class C amplifiers are commonly used in high frequency sine wave oscillators and certain types of radio frequency amplifiers, where the pulses of current produced at the amplifiers output can be converted to complete sine waves of a particular frequency by the use of LC resonant circuits.

Then we have seen that the quiescent DC operating point (Q-point) of an amplifier determines the amplifier classification. By setting the position of the Q-point at half way on the load line of the amplifiers characteristics curve, the amplifier will operate as a class A amplifier. By moving the Q-point lower down the load line changes the amplifier into a class AB, B or C amplifier.

Then the class of operation of the amplifier with regards to its DC operating point can be given as:

Amplifier Classes and Efficiency

As well as audio amplifiers there are a number of high efficiency Amplifier Classes relating to switching amplifier designs that use different switching techniques to reduce power loss and increase efficiency. Some amplifier class designs listed below use RLC resonators or multiple power-supply voltages to reduce power loss.

Other Amplifier Classes

• Class D Amplifier – A Class D audio amplifier is basically a non-linear switching amplifier or PWM amplifier. Class-D amplifiers theoretically can reach 100% efficiency, as there is no period during a cycle were the voltage and current waveforms overlap as current is drawn only through the transistor that is on.
• Class F Amplifier – Class-F amplifiers boost both efficiency and output by using harmonic resonators in the output network to shape the output waveform into a square wave. Class-F amplifiers are capable of high efficiencies of more than 90% if infinite harmonic tuning is used.
• Class G Amplifier – Class G offers enhancements to the basic class AB amplifier design. Class G uses multiple power supply rails of various voltages and automatically switches between these supply rails as the input signal changes. This constant switching reduces the average power consumption, and therefore power loss caused by wasted heat.
• Class S Amplifier – A class S power amplifier is a non-linear switching mode amplifier similar in operation to the class D amplifier. The class S amplifier converts analogue input signals into digital square wave pulses by a delta-sigma modulator, and amplifies them to increases the output power before finally being demodulated by a band pass filter. As the digital signal of this switching amplifier is always either fully ON or OFF (theoretically zero power dissipation), efficiencies reaching 100% are possible.
• Class T Amplifier – The class T amplifier is another type of digital switching amplifier design. Class T amplifiers are starting to become more popular these days as an audio amplifier design due to the existence of digital signal processing (DSP) chips and multi-channel surround sound amplifiers as it converts analogue signals into digital pulse width modulated (PWM) signals for amplification increasing the amplifiers efficiency. Class T amplifier designs combine both the low distortion signal levels of class AB amplifier and the power efficiency of a class D amplifier.

We have seen here a number of classification of amplifiers ranging from linear power amplifiers to non-linear switching amplifiers, and have seen how an amplifier class differs along the amplifiers load line.   

•   Attention : This article  is not original and is reproduced from SAMPATH.ACHANTA. This is his blog  . ALL ABOUT ELECTRONICS AND COMMUNICATION

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The price and stock of  3361P-1-101GLF

Let's see how quickly can you get a bottom price in these distributors! Show us what can you do ! 

Brand	Manufacturer	Description	Stock	Price
Arrow Electronics	Bourns	Res Cermet Trimmer 100 Ohm 10% 0.5W(1/2W) 1(Elec)/1(Mech)Turns 2.77mm (6.71 X 8.53 X 5.21mm) Gull Wing SMD T/R		750: $0.4768
Kynix Semiconductor	BOURNS	TRIMMER 100 OHM 0.5W SMD	5018	inquire in bottom price
Chip One Stop, Inc.	Bourns	Trimmer potentiometer	164	5:$1.3100
Digi-Key Electronics	Bourns Inc.	TRIMMER 100 OHM 0.5W SMD	2,250	0.703
Farnell element14	BOURNS		308	1: £1.52
Farnell element14	BOURNS	TRIMMER, POT, 100 OHM, 10%, 1TURN, SMD	308	1: £1.52
Hybrid Electronics, Inc.	Bourns	Stock	40	inquire
Mouser Electronics	Bourns	Trimmer Resistors - SMD 1/4" SQ 100ohm 10% 0.5WATTS	1276	1:$1.32
Onlinecomponents.com	BOURNS	Res Cermet Trimmer 100 Ohm 10% 0.5W(1/2W) 1(Elec)/1(Mech)Turn 2.77mm (6.71 X 8.53 X 5.21mm) Gull Wing SMD Embossed T/R	20	1: $0.74 100: $0.617
South Electronics	BOUR	date-code:N/A;	750	inquire
Verical, Inc.	BOURNS	Res Cermet Trimmer 100 Ohm 10% 0.5W(1/2W) 1(Elec)/1(Mech)Turns 2.77mm (6.71 X 8.53 X 5.21mm) Gull Wing SMD T/R	464	0.74
Vyrian, Inc.	Bourns		1832	inquire
Newark element14	BOURNS	BOURNS - 3361P-1-101GLF - TRIMMER POTENTIOMETER -000 OHM 1TURN	yes	$:1.330

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Manufacturer Part#:	IS62C256AL-45TLI
Product Category:	Memory
Manufacturer:	ISSI

Package:	TSSOP
Quantity:	11900 PCS
Lead Free Status / RoHS Status:	Lead free / RoHS Compliant
Moisture Sensitivity Level(MSL):	3(168 Hours)

Description:  256K,Low Power,Async,32K x 8,45ns,5v,28 Pin TSOP I (8x13.4mm), RoHS

  Semiconductors have had a monumental impact on our society. You find semiconductors at the heart of microprocessor chips as well as transistors. Anything that's computerized or uses radio waves depends on semiconductors.

  Today, most semiconductor chips and transistors are created with silicon. You may have heard expressions like "Silicon Valley" and the "silicon economy," and that's why -- silicon is the heart of any electronic device. 

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