Earlier this month Fairchild Semiconductor announced the development of a new USB transceiver and USB accessory detection switch that offers functional enhancements without adding design complexity or increasing space and power demands in mobile designs.

The smartphone market is predicted to reach sales of almost 440 million units by 2013 and this growth is a driving force behind the industry's convergence into one universal interface (the micro-USB) for mobile phone applications.

The trend to standardization with micro-USB for charging and data transmission plus the growing demand to create new applications using a USB interface and new charger detection requirements to recognize different USB power sources are all issues posing a series of design challenges which Fairchild claims to address with its new micro-USB switch (FSA9280A) and USB transceiver (FUSB2500).  The new devices aim to provide a number of solutions including space and power savings, auto detection, audio fidelity as well as improved protection functions.

EE TIMES: What are the factors driving the move to standardize micro-USB for charging and data transmission?

Aranzazu Diaz Valdivieso: Previously the smartphone was a small market focused on business people who wanted to use it for communications like email or phone calls or business purposes such as spreadsheets and notes.  Now the market has changed and it seems everybody has a smartphone. Young and old people not just business people.
 
As a result the functions integrated in the smartphone have increased dramatically so now we can see its not only email and phone calls but now you can access the Internet.  You can have GPS.  There are a lot of entertainment applications like video, MP3 players, digital camera and gaming.  In many cases we see that the mobile phone is replacing many of the old portable devices.  For example, many people now do not have an MP3 player anymore because they listen to their music via their smartphone.
 
Everything is going into the one device - the smartphone, - and the accessories are going to be connected to the device via the micro-USB port.  With so many new functions and so many new accessories we need a common port to support all of these accessories. We are going to see most of the accessories are going to be connected to the USB port.  The micro-USB connector has become a worldwide standard for mobile phones.
 
Interestingly in 2009 even though the total handset market declined the smartphone market still grew by more than ten percent.
 
So we can see the smartphone market is going to drive the total handset growth.  By 2013 the Smartphone market is predicted to grow to 439 million units acoording to iSuppli.

EE TIMES: What applications will these devices be useful for?

Aranzazu Diaz Valdivieso: There is a lot of competition relating to new features, new applications, better user interfaces and of course price is very important.

The design strength for USB is that there is going to be a trend through standardization with micro-USB for charging and data transmission.  There is also a trend for creating new applications using a USB interface.  We are already seeing headphones through the USB but in the future we are going to see connection to a docking station or connection to tele-typewriters or even to glucometers.  In the near future you may well be able to connect a glucometer to your USB port, measure your blood sugar levels and send the results directly through your phone to the hospital.  We see these kinds of things coming.

It is also important that charging detection is required to recognize different USB power sources since now when we are charging the mobile phone through the micro-USB port it can be charged from the wall socket, your laptop or even from your car.  So all these new additions pose new design challenges and this is what we are going to see in the next phase of products.

EE TIMES: What are the design challenges this technology is addressing?

Aranzazu Diaz Valdivieso: The design challenges facing mobile phone designers do not just include creating an attractive design with big touch screen LCDs.  They are looking for slim and simple designs.  They want to save power for longer battery life, especially with so many accessories and so many extra features you need to find a way to save power.

You also want to make data communications easier.  It is also important to maintain compatibility with existing accessories in the general market and it is also important to create new features and accessories without compatibility issues.

They also need to keep the bill of materials cost competitive because of the extreme price competition in that market.

EE Times: So which design issues does the new technology solve?

Aranzazu Diaz Valdivieso: The cellphone designers are facing a series of design challenges which include: space saving, compatibility, USB 2.0 compliance, battery life time, competitive BOM costs and protection.

These challenges are being solved either with integration with the devices like the FSA9280A or disintegration using the stand-alone high speed USB transceiver (FUSB2500).

The FSA9280A reduces at least five components while the FUSB2500 decreases total BOM cost along with other component options.  Both products offer a power-saving mode.  Both devices also meet USB 2.0 compliance with a better eye diagram.  They have built-in USB charger detection and protection.  The FSA9280A has audio signal fidelity while integrating which means that the quality of the audio signal is not degraded.  We are using very advanced audio switches that offer negative swing capability without consuming additional power and no click and pop noise.

Often the first design challenge that has to be faced is saving space.  With the current solutions on the market, if you want to have a common connector for all the accessories you want to connect to your mobile phone you will need more than five components.  These will include a USB Switch, an audio switch, a MOSFET, Over Voltage Protection devices, Charger Detect components as well as an ADC.  This takes up a lot of space in your circuitry.  Fairchild is offering the FSA9280A which is replacing all of these components.  The new accessory switch is a highly integrated single chip solution.  With this solution you can just stick an accessory in to your mobile phone’s micro-USB port and the FSA9280A will recognize what kind of accessory it is and will switch the power path accordingly.

The compatibility issue is easy to address with FSA9280A.  With the traditional approach we find that the additional circuitry degrades the USB eye with parasitic capacitance but thanks to the integration in the FSA9280A solution we can overcome this problem and we can maintain a clear eye diagram.

We can also to help with USB 2.0 compliance. With the stand alone USB transceiver the compliance test is also easier.

Since new mobile phone features will consume more power it is important to have a way to save battery life.  What we are offering with the two products, the transceiver and the switch, is a power saving capability which minimize power consumption.  Basically this means when there is no accessory attached and when the device is in stand-by mode the switch and the transceiver will enter a power saving mode.

Competitive Bill of Material (BoM) costs are also achieved with the FSA9280A due to its integration benefits.  

When you have the baseband with the high speed transceiver integrated you need a dedicated power management IC (PMIC) for each phase and chipset which is very expensive.  If you decide to have a stand-alone USB transceiver then you can you use a simple and cheaper general PMIC for all the whole platform.  That would be the advantage of using the high speed transceiver.

I have to say this is a trend we are not really seeing in the market.  We are seeing more of a trend in which the transceiver is being integrated but we are offering the flexibility of a stand-alone USB transceiver in case somebody prefers to do it the other way.

With current designs for protection of the circuitry you need Over Voltage Protection (OVP), Over Current Protection (OCP) and ESD diodes to provide the protection but with the FSA9280A you have OVP and OCP integrated within the device and with the FUSB2500 we have 6kV HBM.

Aranzazu Diaz Valdivieso: FSA800 was essentially a switch that was able to provide a single connector port for charging, audio, USB and UART data.  The new FSA9280A is capable of detecting every accessory.  The new device uses a resistive method.  When you plug in the accessory the switch is able to measure the resistance of the accessory you have plugged in.  Every accessory has a different resistance so it identifies what you have plugged in.  The FSA800 did not know what you plugged in unless it was the charger.  When you plug in another accessory you have to tell the FSA800 through software or another method what you have plugged in and then it can switch.   The FSA9280A on the other hand can do everything by itself.

If the mobile phone manufacturer is not designing a complicated device and all they need is a switch because in their previous platform they have software implemented that recognizes which accessory the user has plugged in then they may well want to carry on selecting the FSA800.  However, if you are designing a new platform and you want to design everything from scratch and you want maximum integration then you would use the FSA9280A because it includes all the functions you would require.

EE TIMES: So in summary why should a designer opt for using the new USB technology?

Aranzazu Diaz Valdivieso: We have a broad targeted portfolio supporting USB connectivity.  We have a lot of analog and power IP to support handset manufacturers’ specific requirements.  Our products for mobile designs complements chipsets in signal path for audio, video, USB, signaling, sensing, timing and also power management for peripheral cores, lighting and RF enable the drive for end-product differentiation.

Our integration skills offer mobile users advantages while reducing the size, power and cost of the designs.

We still have not seen any products like these from other vendors.  We believe we are leading the market and innovating.

Related links and articles:

 
Fairchild releases smallest USB accessory switch equipped with built-in charger detection

FSA9280