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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 how to set up and use the ISL78268 55V synchronous buck controller and evaluation board.

Transcript

Hi, I'm Ed Kohler, Marketing Manager for Intersil's Automotive Power Management Products. Today I'd like to introduce you to the ISL78268, a 55V synchronized buck controller. Then I'd like to demonstrate how easy it is to order and use the evaluation board.

The ISL78268 is a fully synchronous buck controller. What stands out about the ISL78268 is its versatility. It integrates a unique set of features I think you'll find very valuable. Some of those features are: a 5V to 55V input range, integrated 3A drivers with adaptive dead-time control, optional constant current regulation, a selection for light load operation between forced PWM mode for low noise or diode emulation mode for improved efficiency. And it also has a comprehensive set of protection features that includes the ability to select between latch-off or hiccup fault response.

The ISL78268's evaluation board is a great way to try out any of these features. It’s easy to order and to use. To get one, you just need to visit the ISL78268's page on our website. Just click over to the order tab and then scroll down to find the evaluation board's part number. That's ISL78268EVAL1Z.

When the board arrives, this is what you should get. Inside, you'll find the ISL78268 evaluation board along with documentation. There will be a user guide for the evaluation board and a datasheet for the ISL78268. To get started, all we need is a power supply, a load and some cables. So, I'm using a dual 30V supply that I've set to operate in series mode so I can deliver up to 60V to the input because I want to check out the ISL78268's wide input voltage range. And I've preset my load to 5A so that should do it. Let's get started.

Okay, let me show you what I've done here. First, I installed jumpers at J28 and J10. This allows the part to automatically be enabled when the input supply comes up. Then I connected my upper meter to the input voltage monitoring test point and I connected my lower meter to the output voltage monitoring test point. Then I connected my supply to the input voltage and my load to the V_OUT terminals. Now, if I enable the supply...you can see I've set it up for 48V so I'm regulating 48V at the input to 12V at the output. Now, if I enable the load, we see that we maintain the 12V regulation, as you'd expect.

Now, I also have put an oscilloscope probe on the phase node so that we can see the switching action. If we look at the oscilloscope, we see that we're switching at 300kHz which is default and the phase node is going between ground and being at 48V, as we'd expect. Here I can demonstrate the overvoltage response at the input.

So if I increase the input voltage to over 55V, at typically around 58V the overvoltage protection will kick in and stop the part from switching. And there we have it, stop switching. Now, if we allow the voltage to come back down below the overvoltage threshold, we see that the switching starts again and we're regulating again at 12V. The evaluation board lets you check out all the features of the ISL78268, and don't worry, the documentation will walk you through how to do all of that.

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.

ISL8117 is a high voltage controller that gives the power supply designer an opportunity to optimize their design for cost, size and efficiency. (Part 1)

Transcript

High Voltage 60V Synchronous Buck Controller Introduction

Hi, I'm Dhananjay Singh, Product Manager at Intersil Corporation.

Today we are going to introduce a highly innovative high voltage controller, ISL8117. It runs from 4.5V to 60V. Output can be adjusted from 0.6V to 54V. It has a variable switching frequency that can be adjusted from 100kHz to 2MHz. This gives the power supply designer an opportunity to optimize their design for cost, size and efficiency.

In this particular IC, we use valley current mode with adaptive compensation that allows us to go for a very small duty cycle. In fact, minimum on time of this device is 40ns, which is best-in-industry, and it allowed us to generate 1V power supply directly from a 48V rail.

In essence, ISL8117 is a simple, easy to design controller that helps a power supply designer in terms of less circuit design, layout design and total cost. ISL8117 is an ideal solution for a board which uses multiple rails and has high voltage input.

Learn how the ISL8117 buck (step-down) PWM controller reduces design time and takes up less real estate on the board than competing devices.

Transcript

ISL8117/A 60V Synchronous Buck Controller

Welcome to the ISL8117 and ISL8117A 60V synchronous buck controller product training.

Today, we are here to introduce Intersil’s innovative high voltage controller. Before we go into the product discussion, let me quickly go through the analog controllers that Intersil has to offer. We offer a large selection of product with a variety of functional and protection features to address different customers’ needs.

Here is a quick table of Intersil’s analog controller products in different categories. This is just a sample of products available in each product category. For example, we picked the ISL6446 in the dual output category, but we do have multiple solutions in that category. We’ve also included details on the ISL8117 60V synchronous buck controller, and the ISL8117A 60V synchronous buck controller with external compensation.

ISL8117/A: An Innovative 60V Sync Buck Controller

Here is the brief introduction of the part we are going to talk about, the ISL8117/A. With this part, we are looking to simplify the controller based power design. The ISL8117/A offers reduced design time and solution cost; it is easy to use, thus simplifying the design process; and, it takes up less real estate on the board with 40% fewer external components than competing devices. The ISL8117/A also offers up to 98% efficiency and 1.5% output voltage accuracy.

ISL8117: High Voltage 60V Buck Controller

Let’s have a quick look at what the ISL8117 has to offer and what that means to end customers or applications. In high voltage applications where a lower output voltage is required, designers have traditionally relied on modules that increase system cost, or two stage DC/DC solutions that increase solution footprint and complexity. The ISL8117 controller offers a cost-effective and reliable alternative for applications where the V_OUT to V_IN ratio is low. The ISL8117 uses valley current mode modulation with adaptive slope compensation to enable stable operation for a wide range of V_IN and V_OUT combinations, with no external compensation required.

Other key features and specifications include:

• Wide input voltage range of 4.5V to 60V that covers all standard input rails including 5V, 12V, 24V, 36V, 42V, and 48V
• Wide voltage output range that is configurable from 0.6V to 54V
• Smallest min on time in the market, which enables a very low duty cycle power supply and eliminates the need for a two stage solution in many applications
• Programmable 100kHz to 2MHz switching frequency can be synchronized to reduce radiated system noise and avoid beat frequency issues
• Complete fault protection for long term reliability including overvoltage, undervoltage, overcurrent, and overtemperature
• High current FET drivers and DEM mode operation ensures efficiency at all load levels
• Adjustable soft-start with pre-bias support enables the sequenced startup of multiple ISL8117 controllers

Target applications for the ISL8117 include:

• After market automotive electronics
• Amusement machines
• Security surveillance
• Factory automation/ATM machines
• 48V telecom and networking systems

ISL8117A: 60V Buck Controller w/External Compensation

The ISL8117A allows for external compensation, as compared to the internal compensation used in the ISL8117. The differences between the ISL8117 and ISL8117A are covered in the next slide.

ISL8117 vs. ISL8117A

The CLKOUT pin of the ISL8117 is replaced by a COMP pin in the ISL8117A.

The COMP pin brings wider flexibility in compensation design.

The COMP pin gives the user wider choices of external components.

All other functions remain the same except the pin configuration.

The ISL8117A is targeted for power module customers.

Valley Current Mode with Adaptive Compensation

Here, we show a comparison of different modulator schemes used in high voltage to low voltage power conversion. When the upper MOSFET turns on, nodes can be very noisy in terms of voltage and current. The turn ON noise limits the practical minimum on time possible in a peak current mode controller. In valley current mode, useful information is derived when the LFET is ON, thus staying away from noisy UFET signals. Adaptive slope compensation on a valley current mode provides stable compensation across a wide range duty cycle. The adaptive slope compensation is adjustable and Intersil has employed voltage feed forward (VFF) in its modulator. The combination of these two features provides the ISL8117/A with the benefits of both a voltage mode and current mode modulator.

Delivers High Efficiency Performance

Efficiency not only helps power consumption, it also improves system reliability. More efficiency means less heat and hence reliable operation. The ISL8117/A has multiple features to boost efficiency across all loads. For example, the strong driver supports high current MOSFETs and boosts efficiency at higher loads. External bias saves internal LDO losses, hence boosting efficiency on the boards where a 5V rail is readily available. ISL8117 also has DEM mode with pulse skipping, which boosts efficiency at light load without introducing a variable frequency like PFM mode. ISL8117 runs on a very low Iq of 2.5mA which helps in lighter loads and prolongs battery life. The graph on the right side of the slide gives a clear idea of the impact that external bias and DEM mode makes in terms of efficiency. As you can see, at 1A load efficiency, the difference is 9%.

Simplifies Three Phases of Design

Here is an easy explanation on how the ISL8117/A makes a system designer’s life easy by making power supply design simple. There are three aspects of power supply design: component selection, circuit design and layout design. ISL8117/A makes design easy on all three fronts.

Component selection: First, you need to select the ISL8117/A. Once the ISL8117/A is selected, a designer may not need to select another controller for a different rail on the board or system because the ISL8117/A covers a wide range of input and output combinations. The ISL8117/A has a very low pin count and uses less external components. Its internal compensation and internal default design values further reduce the number of required external components.

Circuit design: Less pins and fewer components directly translate to a less complicated circuit. Internal compensation reduces the design effort even further.

Layout design: The ISL8117/A pin architecture has been designed in such a way that it can run on a bare minimum circuit for a basic buck converter. All additional function/feature pins have default values and can be sorted out without any additional components. All high power pins and signal pins are placed on opposite sides, therefore reducing any chance of interference. The ISL8117/A pins are organized to avoid layout errors by avoiding trace overlaps.

Beat Power Design with Simplicity: ISL8117

Here is a rough comparison between two solutions for a 42V to 12V power conversion. From the circuit and as listed here on this slide, it is clear that for the same power specification, the ISL8117 uses less pins, less external components and is less complicated. The default values of different pins in the ISL8117 helps the designers immensely in terms of circuit design effort if they don’t have any complicated spec requirements.

ISL8117: Best-in-Class High Voltage Controller

In the 60V category, Intersil’s ISL8117 offers multiple best-in-class features that matter most to industrial customers. Critical parameters like switching frequency, minimum on time, IC pin count, number of external components, easy layout design, and strong gate drivers all give tangible benefits in real-world applications.

ISL8117: Evaluation and Reference Design Boards

To serve customers better, we have designed multiple evaluation and reference design demo boards for different markets—the larger evaluation boards to learn about product details and the smaller reference design demo boards to create practical and optimal designs. We have separated the evaluation boards and reference boards into two different categories—one for low current markets such as industrial and robotics and the other for high current markets such as telecom and power modules.

ISL8117A: Evaluation and Reference Design Boards

The ISL8117A also has evaluation boards for the two categories and a reference demo board for the low current market.

ISL8117EVAL1Z Reference Design for 20W Output

Let’s take a look at the ready-to-use reference designs. This is a basic design using the ISL8117 in the HTSSOP package. Input can be any voltage from 4.5V to 60V and output is set at 3.3V for 6A of load current. Please note that if the designer does not have any specific requirements on different functional pins, such as soft-start or rise time (RT), those extra components can be saved by using the default internal values. Also note that the EXTBIAS pin is grounded since it is not used. If we have an external power source of 5V or you can create a 5V supply, efficiency can be boosted further, as we saw in previous slides and in next couple of slides.

ISL8117DEMO3Z and ISL8117ADEMO1Z Reference Design for 20W Output

The ISL8117DEMO3Z and ISL8117ADEMO1Z are similar to the ISL8117DEMO1Z, except they use the QFN package and reduce the switching frequency to achieve even higher efficiency. The ISL8117ADEMO1Z also has external compensation. The input and output are easily connected to a circuit for testing purposes or as part of a prototype.

ISL8117DEMO2Z Reference Design for 240W Output

The ISL8117DEMO2Z is a 240W 12V design. It delivers 98% efficiency when the input voltage is 18V—the complete design is configured into a 40mm x 35mm board area.

ISL8117DEMO2Z Schematic

Here is the circuit for the 240W design. As you can see, we are using an external LDO in order to boost the efficiency. If you have an available 5V source, you can depopulate the LDO. The ISL8117 will automatically switch to internal LDO mode and take care of it. If your output is 5V, then you just need to connect your output to this pin and the ISL8117 will self bias itself from its own output.

Industrial Applications: Networking and Communications

Customers are showing an increasing amount of interest to move away from intermediate stages and utilize the higher input voltage bus. The 12V intermediate bus, though well established, has added complexity and distribution losses. A high voltage bus allows users to eliminate the extra conversion bus where ever necessary and improves system cost and efficiency. Here is an example of a microwave communication system where a traditional 12V bus can be eliminated to improve system cost and efficiency.

Industrial Applications: Medical Diagnostics

Here is another example of a high voltage application where intermediate rails are being used. The common input rail in industrial applications are 42V, 36V or 24V. These rails normally see a peak voltage which is 15% to 25% higher than the nominal voltage.

There are three different reasons this input voltage variation occurs:

1. Poor power source,
2. Fully charged battery voltage is higher than the nominal voltage,
3. Voltage spike occurs when load is disconnected and the spike value depends on source quality and input capacitor.

In addition, these types of customers want an extra margin of safety. For a 24V battery system, an input requirement of 42V is very common.

This slide shows an example block diagram of an ultrasound machine, which uses an input rail of 24V or 36V along with a battery backup system. They typically have 20 to 25 power rails. Three to four rails are high power rails to drive DSPs, CPUs and FPGAs. In general, the input rail is first converted to 12V and or 5V rails. The ISL8117/A and other high voltage products are well suited for these applications. They use different power topologies such as buck, boost, LDO, display drivers, and simple voltage inverters among others.

ISL8117/A: Other Target Applications

Other applications that are ideal for the ISL8117/A 60V synchronous buck controller include high power LED panel/hoardings, power modules, after market infotainment, and 24V/36V battery power applications to name a few.

Renesas Investing in Industrial Power

The ISL8117/A is an innovative high voltage controller designed to address major concerns of industrial customers.

The ISL8117/A 60V controller simplifies industrial power supply designs by:

• Eliminating the intermediate step-down stage and allowing 48V to 1V conversions
• Providing internal default design settings
• Improving on efficiency (up to 98%) by using a low operating current and DEM/pulse skipping

Complete evaluation and reference design boards for the ISL8117/A are available to enable design replication and faster time-to-market.