High Voltage Buck Boost Controller

Added on 10月 02, 2018

ISL81601 is a true bidirectional 4-switch synchronous buck-boost controller for efficient DC-DC power conversion with peak and average current sensing and monitoring at both ends. It provides cycle-by-cycle current limit in both directions while in buck or boost mode, and generates point-of-load (POL) and voltage rail conversions with peak efficiency up to 99%. The controller uses a proprietary buck-boost algorithm that allows inherent peak current sensing for a robust design and produces the smoothest mode transitions between buck, boost and buck-boost. Its proprietary algorithm reduces low frequency ripple at Vout, ensuring minimal disturbances during line or load transients. The algorithm also ensures predictable ripple voltage under all conditions. The ISL81601 features multilayer overcurrent protection (OCP) that helps designers to design a charging/discharging circuit that ensures constant current operation for safe and reliable battery power applications. It is available in 32LD 5mmx5mm QFN and 38LD HTSSOP packages and provides full protection features such OVP, UVP, OTP and OCP. ISL81601 is a 4.5Vin~ 60Vin device and the ISL81401 is a 4.5Vin~40Vin device. The ISL81401A is a low cost unidirectional version of the ISL81401.



Video Transcript

JEFF STRANG:

Hi, I'm Jeff Strang, product line director for Renesas Electronics Industrial Power Product Family. I'm here today with DK Singh, our product marketing manager, so that we can talk about our new family of high voltage buck-boost controllers, DK?

DK SINGH:

Thanks, Jeff. Hi, I'm DK Singh, product marketing manager for industrial power products at Renesas Electronics. Today, we are introducing true bi-directional high voltage buck-boost controllers. These products use a unique architecture that enables circuit designer to implement a true bi-directional circuit by sensing true peak inductor current in both sides and in both directions.

These controllers have four independent control loops to manage and control voltages and currents at both ends. It ensures high operational reliability by providing instant current limit in a fast transient condition at both input and output ends. The ability to limit negative peak current accurately allows users to exploit the bi-directional operation, and optimize overall

battery backup system for battery utilization and the battery health. CC operation down to a very low voltage

avoids any runaway condition in the event of overload or short circuit.

The new high voltage buck-boost controllers from Renesas Electronics are highly integrated and provide a robust solution for battery backup designs. Some of the other key features are multilayer overcurrent protection and multiple functions, such as light load efficiency mode, external bias, and low quiescent current to improve the battery runtime. In summary, a true bi-directional buck-boost controller for DC power applications provides utmost efficiency and improves overall system reliability. Do you have any questions?

JEFF STRANG:

Thanks, DK. These are very impressive new products, lot of capabilities in them. Let's start with one that comes to mind immediately. Why do we call these "true" bi-directional buck-boost controllers?

DK SINGH:

That's a very good question. Actually, these controllers have a unique architecture that allows user to sense true peak current at both ends and in both directions. And having true peak current information allows the users to avoid extra circuitry required to get those information.

JEFF STRANG:

So when we talk about measuring the current, I expect that energy management is a big deal, important application for these controllers. What type of energy storage devices do we support?

DK SINGH:

This is designed for a wide variety of energy storage devices. But we have really tested on a few types in our lab, such as lithium ion batteries, lead acid batteries, and even with supercapacitors. The point is these devices are allowed to change all the settings even the live current and voltage settings on the fly. So all the parameters can be adjusted on the fly according to the battery type and battery chemistry.

JEFF STRANG:

All right, so whether we're powering and charging a super capacitor, or a lead acid battery, or a lithium ion battery, I expect that efficiency is very important. Can you talk about what we've done to optimize efficiency in these sorts of battery powered and supercapacitor powered applications.

DK SINGH:

So we have three stages of efficiency improvement modes: for heavy load we go into CCM mode, for medium loads we go into DCM mode. And at very light load, we move into burst mode where it is allowed to skip cycles.

At the same time, we also have external bias feature that allows the user to use any power rail available on the board, such as five volt, 12 volt, or even 24 volt. It support up to 36 volt. So user can use any ready made available rails on the board and save energy from the main rail. We also have a very low quiescent current considering this is a 60 volt device.

JEFF STRANG:

OK, so what are some other major features of these controllers that you'd like to highlight?

DK SINGH:

We have tried to make this device as universal as possible, so we have a long list of features. But I would like to stress on a couple of them, which is more universally talked about, such as the dithering feature to get control over EMI issues. We also have frequency synchronization, again, to play with EMI or any frequency noise issue that user might have.

OK, so it can be synchronized to any switching frequency, either with the system or any other device. Additionally, this device is also capable of running in parallel. That means if one controller can deliver up to 100 watt, and if you need more power, you can parallel two, three, four, and get more power. And all those parallel operations are interleaved, and that, again, saves user on input capacitor side.

JEFF STRANG:

Very impressive. So not only do we have two different ways to control EMI, both with dithering and with clock synchronization to a master clock. But you can also parallel these modules if you need more power then you can get from a single one.

DK SINGH:

That's correct.

JEFF STRANG:

Thanks, DK. That was very interesting. To learn more about Renesas Electronics new high voltage buck-boost controller family for battery backup applications. And to get information about our evaluation boards and design tools, visit renesas.com.