降圧レギュレータ（FET内蔵）

The RAA211x family of bucks are highly scalable due to its unique pin-compatible wide Vin buck variants with integrated FETs that support up to 5A of continuous output current with premium load and line regulation performance. The RAA211835 supports 75V async buck operation of 3A loadings, while RAA211250/450/630/820 support sync buck operation of 30V 5A, 40V 5A, 60V 3A, 75V 2A respectively.

Find out how Intersil's high efficient, compact 12V synchronous buck regulator family can meet your power requirements for 12V rails in industrial and infrastructure applications.

Transcript

12V Synchronous Buck Regulator Family

Today I would like to introduce one of the most efficient and compact synchronous buck regulator families in the marketplace today.

There are many 12V rails in industrial applications today that need a buck converter to step the voltage down to a lower voltage and deliver up to 14A. Some of these applications often require a very efficient and compact solution. The highly integrated buck regulators listed here allow the users to meet all these requirements.

The ISL85009, ISL85012 and ISL85014 are pin compatible, very efficient and are able to deliver up to 14A. In applications that need less than 5A, Renesas offers ISL85003 and ISL85005 that are pin compatible. The ISL85009, ISL85012 and ISL85014 can operate from 3.8V to 18V input voltage, and the output voltage can be set as low as 0.6V. This family is highly integrated. The high-side and low-side FETs, with a bootstrap diode and compensation circuits are all integrated which helps to reduce the size, cost and bill of material.

This family is also highly reliable. It has high-side and low-side overcurrent protection, input and output overvoltage protection, over-temperature protection and negative current protection all integrated in the IC. This family also provides full feature sets and design flexibility to customers.

For instance, the selectable OCP scheme feature gives flexibility to the power supply designer to choose between hiccup and latch-off OCP mode, depending on their application requirements. Finally, the ISL85009, ISL85012 and ISL85014 are pin compatible, highly efficient and capable of delivering up to 14A in a very small 3.5mm x 3.5mm TQFN package.

As you see in the efficiency curve here, the ISL85009 provides one of the most efficient solution in the marketplace today. To support our customers with this family, we have developed several evaluation and demo boards.

Supporting tools such as iSim model, PowerCompass, schematic and Gerber files are all available online for this family on our website. 

This video introduces the ISL85003 and ISL85003A synchronous buck (step-down) regulators with integrated high-side and low-side FETs.

Transcript

ISL85003/3A

4.5V to 18V 3A Synchronous Buck Regulators

I want to introduce you to our synchronous buck regulators, ISL85003 and ISL85003A with an input voltage of 4.5V to 18V giving an output current of up to 3A.

ISL85003/3A – Integrated Synchronous Buck

The ISL85003 and ISL85003A are synchronous buck regulators with integrated high-side and low-side FETs. The high-side and low-side FETs are designed to have a very low RDS(ON) of 65 and 45m. Lower RDS(ON) simply means lower conduction loss which leads to higher efficiency. This device provides a very low BOM and a very compact solution because it has integrated high-side and low-side FETs, integrated bootstrap diode, internal compensation, an internal soft-start, all in a very compact 4mm x 3mm DFN package. In this device, the switching frequency is internally set to 500kHz. Operating at high switching frequency has two main advantages: 1) It provides a better transient performance; 2) It gives the option to choose smaller sized passive components which leads to an even more compact solution. The main difference between the ISL85003 and ISL85003A is the functionality of Pin 1. For the ISL85003, Pin 1 is used for external synchronization up to 2MHz. For the ISL85003A, Pin 1 is used to adjust soft-start time. Finally, this device is fully protected against overcurrent, over-temperature, overvoltage, and so on.

Differentiating Features

As I explained in the previous slide, the ISL85003 provides a very simple, efficient and compact solution. There are important features that differentiate this part from our competitors:

1. This part can automatically switch from CCM to DCM to improve the efficiency at light load;
2. The built-in negative current protection helps to improve the reliability; and
3. This part can support pre-biased output.

Applications and Markets

There are many applications for these parts including servers, computing, industrial control, network switchers, data storage or anywhere that we have a point-of-load such as 12V or 5V.

Efficiency Performance (12V_IN in CCM)

This graph shows the efficiency vs. load of the ISL85003 for 12V_IN and different output voltages at ambient temperatures. As you can see, the efficiency is very high and it is very flat over the full load range.

Efficiency Performance (12V_IN in DCM)

At light load conditions, the device operates at DCM to improve the efficiency. This graph shows the efficiency is very high at light load range for 12V_IN and different output voltages.

ISL85003 Regulation

This graph shows another important feature of this part. As you can see, ISL85003 provides a very high line and load regulation which is an important feature for many applications.

Evaluation and Demo Boards

To help evaluate the ISL85003 and ISL85003A, the evaluation and demo boards are available and designed for easy set-up and test in the lab. We can provide schematic and Gerber files if needed. Also, demo boards are available for free for our customers.

Tools

Information for the ISL85003 and ISL85003A including datasheet, application notes, schematics, Gerbers, are all available online.

Learn more about the ISL8018 synchronous buck regulator and how to incorporate this device into your designs.

Transcript

8A, Low Quiescent Current, High Efficiency Synchronous Buck Regulator

Hello and welcome to the ISL8018 8A high efficiency buck regulator training.

Intersil Integrated Switching Regulators

Let’s start by taking a look at the key value propositions of Renesas' integrated FET switching regulators.

1. High level of integration: These ICs integrate PWM control, drivers and the power FETs/switches in one small package, hence enabling high power density. Furthermore, some of Intersil’s integrated FET regulators integrate various value-added features such as power-good, enable, start-up tracking, and frequency synchronization (to external clock). These features can eliminate the need for discrete ICs,such as monitors and sequencers, and provide a complete point of load (POL) power management solution at a lower cost. Intersil’s portfolio also includes dual and triple output regulators that help address the power requirements of multi-POL systems or applications.
2. Different switching frequency options: The large portfolio provides various frequency options to optimize designs. Low switching frequency solutions provide higher efficiency, whereas higher frequency solutions provide the advantage of a small overall design footprint. Many devices have adjustable switching frequencies for greater flexibility.
3. Various output current choices: Intersil’s switching regulators family has an extensive offering for various load current requirements with solutions optimized for load requirements as low as 150mA to as high as 10A.

ISL8018: High Efficiency 8A Internal FET Buck Regulator

The ISL8018 is Intersil’s latest 5V switching regulator; it supports a continuous load of up to 8A. It accepts an input voltage of 2.7V to 5.5V and can provide an output voltage of 0.6V to VIN, thanks to the ability to run in 100% duty cycle mode. It has outstanding efficiency of up to 97% and can maintain high efficiency even at low loads thanks to the pulse frequency mode (PFM) for light load operation. In addition to more common features like synchronization to external clock and power-good/enable, the ISL8018 integrates some differentiating features that provide significant value added.

First, it provides bidirectional SYNC to eliminate the need for a system clock to synchronize multiple ICs to the same frequency, in order to reduce or eliminate beat frequency. Furthermore, it has programmable phase-shift and a programmable current limit; this provides the benefit of overcurrent protection (OCP) even while operating at lighter loads compared to the rated 8A capability of the IC, which is key to proliferating the IC for various POLs in a particular system and/or various different systems with varying load requirements. The ISL8018 also has a negative current limit to improve reliability.

The ISL8018 also provides output voltage margining, which integrates the ability to margin the output voltage by ±10% to help check for overall system robustness. The adjustable switching frequency from 500kHz to 4MHz allows a trade-off between high efficiency and extremely small filter size. Finally, adjustable soft-start and start-up in pre-biased load provides the customer/application with complete control for a monotonic start-up.

ISL8018 Block Diagram

This is the block diagram of the ISL8018. When FS is connected to VIN, the loop is internally compensated to meet the needs of most applications and the switching frequency is set to 1MHz. The output voltage can be margined by ±10% using VSET. This feature is valuable for compensating the IR dropped due to far away system load by increasing the voltage up 10%. VSET can be lowered by 10% to reduce system power dissipation. In addition to these features, the output current can be adjusted to 3A, 5A or 8A using ISET pin.

Multi-chip Operation

In an application with two or more ISL8018s, use the SYNCOUT pin to allow the channels to run at the same frequency and out-of-phase. By adjusting the SYNCIN capacitor of the slave IC (in this case C7), adjustable phase-shift delay is achieved.

How Programmable Phase-Shift Work

Here is the timing sequence of the phase delay. The SYNCOUT feature of the master IC turns on a 250µA current source at the beginning of its clock cycle and charges up C7. As the voltage rises to 0.7V, the SYNCIN of the slave IC starts its ON pulse. By changing the value of C7, timing can be delayed. If there are more ICs, then the SYNCOUT of the second IC can drive the third and so on.

Operating Out-of-Phase

One big benefit of operating in an out-of-phase system is input current ripple is minimized. If we compare three converters operating in-phase, the peak input current would be 24A or 12ARMS at 50% duty cycle. On the other hand, an out-of-phase system would have an 8A peak or 4.3A at 50% duty cycle. Thus, significantly reducing the input capacitor requirements and EMI spectrum.

Applications

Common applications for the ISL8018 include test and measurement systems, power for microcontrollers and FPGAs, and plug-in DC/DC modules for routers and switchers.

Helpful Design Resources

Several tools are available to aid in designing with the ISL8018. Along with the datasheet and app notes, two boards are available as well as iSim.

ISL8018EVAL3Z Evaluation Board

The ISL8018EVAL3Z is an evaluation board that can be checked in the lab for efficiency and all other features highlighted previously. It is designed for full feature testing, and as such includes additional components that need not be in a final design.

ISL8018DEMO1Z Demo Board

On the other hand, the ISL8018DEMO1Z is a compact 8A demo board that demonstrates a small form factor to fit most applications or quickly connected to another board in a system. The solution size is 0.64” x 0.28”.

How to Access ISL8018 on iSim Online

To access the iSim model online, find the ISL8018 simulation model in the documents tab of the product landing page. You can also find the device in the parametric search table and click on the iSim logo in the far right column.

Designing the Circuit in iSim

Once the part is selected, enter the desired input voltage, output voltage and output current. Click on the Design button and a schematic with typical component values will be generated. Alternately, select custom design to specify the input and output capacitors and the inductor.

iSim

The iSim model allows a customer to incorporate the ISL8018 into a simulated design to test circuit functionality before prototyping, and to observe AC analysis, transient responses and start-up times in the system. Tabs along the side allow adjustments to the efficiency and compensation, as well as providing a bill of materials. The design can also be downloaded and used with the offline tool, iSim PE.

Single Output Switching Regulator Product Portfolio

Intersil has a large portfolio of over 80 single output switching regulators optimized for various load currents and input voltage requirements. This graph captures a selection of these devices. The X-axis indicates the input voltage range supported by the products and the Y-axis indicates the rated output current capabilities.

The 5V family of regulators, which includes the ISL8009A, ISL80030 and ISL8018, support maximum load currents from 1.5A to 8A.

The 12V/24V single output product portfolio includes products such as the ISL85001, ISL85003 and ISL8505 that support maximum load currents from 1A to 5A.

We also offer solutions that support voltage inputs of up to 40V and 60V. These include the ISL8540 and the ISL85403 for 40V, and the ISL8560 for 60V.

Multi-Output Switching Regulator Product Portfolio

There are numerous multi-output switching regulators as well. The strategy behind developing a family of multi-output regulators is to complement our portfolio of single output solutions for applications/systems that have more than one point of load.

The availability of dual and triple output solutions enables the customer to optimize their design for lower overall system cost, as well as smaller overall system form factor, compared to using multiple single output solutions.

Intersil’s multi-output family consists of various products that support a wide range of load currents from 800mA to 6A, and a wide VIN range with solutions supporting <5V, 12V/24V and 28V input supplies.

As can be noted from several of these devices, some applications may require an additional low dropout regulator (LDO). Intersil has a large portfolio of LDOs as well.

Summary

In summary, the ISL8018 is an 8A highly integrated synchronous buck regulator that provides high efficiency and a wide range for the switching frequency. Its bidirectional synchronization with programmable phase-shift reduces ripple current and noise in the system, while the selectable output current limit and output voltage margining can be adjusted depending on the needs of the application.

Learn about the ISL8002B 2A synchronous buck (step-down) regulator in this recorded webinar.

Transcript

ISL8002B 2A Synchronous Buck Regulator

Welcome to the ISL8002B 2A Synchronous Buck Regulator training presentation.

The growing number of voltage input rails for delivering point‐of‐load power to DSPs, ASICs, FPGAs, and microprocessors is making power supply designs more challenging. As system power and operating frequency demands increase, this can cause infrastructure and industrial equipment to be more sensitive to noises and other unpredictable events. For example, false inputs at start up can trigger system latch up, cause severe reliability issues, or even complete system failure.

This presentation provides an overview of Intersil’s ISL8002B 2A synchronous buck regulator and discusses how to configure the various voltage output tracking and sequencing options for an FPGA point‐of‐load application that will enable the proper start up and shut down of sensitive multi‐rail systems using the ISL8002B. We will examine the ISL8002B’s external soft‐start, and other various tracking configurations that will prevent for example, an FPGA’s internal electrostatic discharge (ESD) diodes from ever biasing. The configurations we will be discussing will significantly improve the FPGA’s system reliability which is vital to the productivity and longevity of a broad range of infrastructure systems and factory floor industrial equipment.

ISL8002B Synchronous Buck Highlights

The ISL8002B highlights include higher reliability and efficiency for infrastructure and industrial point‐of‐load applications.

The features of the ISL8002B, which we discuss in detail, include:

• Programmable soft‐start
• Ratiometric tracking
• Coincidental voltage tracking
• Output sequencing

The ISL8002B is a very reliable, fully integrated 2A synchronous buck regulator. The peak efficiency of 96% is achievable at light load conditions. The device has only eight pins and other features that the competition does not offer.

ISL8002B Features

The following slides discuss the key features of the ISL8002B.

ISL8002B Offers Output Tracking and Sequencing

As mentioned previously, the ISL8002B is a 2A compact synchronous buck regulator. The input voltage range is from 2.7V to 5.5V. It also features programmable soft‐start, output tracking and sequencing. The switching frequency is set to 2MHz in order to reduce the filter component’s size while still maintaining high efficiency. The modes are selectable from forced pulse width modulation (PWM) or pulse frequency modulation (PFM). The PFM feature increases the efficiency when driving light load currents. The ISL8002B also has overcurrent, short circuit, thermal, and undervoltage lock out (UVLO) protection. The programmable soft‐start, output tracking and sequencing are the important features for which we will go into more detail in the following slides.

The part is offered in a small 2mm x 2mm TDFN package, which provides a high power density design utilizing minimal PCB board space.

Programmable for Soft-Start/Tracking

This diagram shows a typical application circuit for the ISL8002B with an input voltage range of 2.7V to 5.5V. Only a few external components such as resistors, capacitors and one inductor are required. The converter integrates the compensation and the power MOSFETs to guarantee design robustness, minimum part counts and high efficiency up to 95%. The converter’s Pin 5 provides both soft‐start (SS) and output tracking (TR) functions. When this pin is high, the soft‐start time is internally set to 1ms; however, various soft‐start times can be achieved using external components.

External Soft-Start Config Controls Output Rise Time

The ISL8002B soft‐start time can be configured using external components. The output rise time can be controlled by a adding a resistor and capacitor (RC) to the soft‐start tracking (SS/TR) pin. The resistor and capacitor combination will set the output rise time according to the Css equation shown on the slide. If the values Rss and Css are known, then the equation can be solved for the desired output ramp time (Tss).

The diagram on the left shows the application circuit and the typical output waveform illustrating the Tss rise time as a function of the Css and Rss values. The waveforms on the right are the actual soft‐start waveforms measured on the ISL8002B demonstration board.

Ratiometric Tracking of Multiple Output Rails

The soft‐start feature described in the previous slide can also be configured for tracking more than one output voltage rail. The diagram shows a ratiometric tracking configuration of Vout1 to Vout2. Simply connect the two SS/TR pins together to force the two output voltages to rise at the same time. Similarly, the shutdown function also tracks each other ratiometrically.

This configuration is not limited to just two devices. Multiple devices can be configured by simply connecting all of the SS/TR pins together for complete output voltage tracking.

The diagram on the left shows the application circuit and the typical output waveform illustrating the Tss rise time as a function of the Css and Rss values. The waveforms on the right are the actual ratiometric tracking waveforms measured on the ISL8002B demonstration board, illustrating the timing of Vout1 and Vout2.

Coincidental Voltage Tracking for Multiple Rails

This diagram shows the ISL8002B coincidental tracking configuration. This is accomplished by simply adding a resistive divider that is the same ratio as the output voltage sense divider in the feedback loop.

In this case, all the output voltages ramp up with the same voltage and slew rate from the first main output rail.

Typically, all outputs will track to the part with the highest voltage rail. Afterwards, each output “branches” as they reach their regulation point.

The diagram on the left shows the application circuit and the typical output waveform. The waveforms on the right are the actual coincidental voltage tracking waveforms measured on the ISL8002B demonstration board.

Output Sequencing Controls Multiple Devices

Another feature of the ISL8002B is output sequencing, used to control more than one device. Output sequencing allows voltage rails to come up sequentially in order to reduce in‐rush current. This is accomplished by using the power good (PG) feature from the first ISL8002B regulator (top) to control the device enable (EN) of the second regulator (bottom). As shown in the waveforms, the output waveform (Vout1) from the top regulator ramps first, followed by the second regulator (Vout2).

The diagram on the left shows the application circuit in the typical output waveform. The waveforms on the right are the actual output sequencing waveforms measured on the ISL8002B demonstration board.

Support Tools

Let’s discuss the support tools available for the ISL8002B.

ISL8002B Demo Board Jump Starts Design!

The ISL8002BDEMO1Z demonstration board is available for evaluating the ISL8002B synchronous buck regulator and is optimized for size, cost and performance. The board is an actual working circuit and the design can be replicated into a system layout. The demo board PCB design files are downloadable free of charge from our website.

The ISL8002B features are highlighted on the demo board and include programmable soft‐start, output sequencing, ratiometric tracking, and coincidental tracking. These tests are easily setup and are clearly documented in the ISL8002BDEMO1Z User’s Guide. The ordering information and MSRP price for the demo board is shown on the slide.

ISL8002B Support Material

Intersil provides a complete list of ISL8002B design support material. The support material includes:

• The ISL8002B datasheet
• The ISL8002B PCB design files
• iSim online simulation model
• ISL8002BDEMO1Z demonstration board
• ISL8002BDEMO1Z User’s Guide

Please check the ISL8002B product page on our web site for the latest documentation.

ISL8002B Summary

In summary, the ISL8002B is a very reliable, fully integrated 2A synchronous buck regulator. The device provides output tracking and sequencing ideal for use in designs with multiple rails, typically FPGA applications. The ISL8002B offers a small 2mm x 2mm TDFN package which has the advantage of being designed into very small space constrained areas on the PCB board. The switching frequency is set to 2MHz in order to reduce the filter component’s size while still maintaining high efficiency. And, the ISL8002B is reliable in all thermal and performance conditions.

Thank you for listening to the “ISL8002B 2A Synchronous Buck Regulator” training presentation.