ISL85003/3A Sync Buck Regulators

Added on June 10, 2014
Intersil introduces the ISL85003 and ISL85003A synchronous buck (step-down) regulators with integrated high-side and low-side FETs.


Video Transcript


4.5V-18V 3A Synchronous Buck Regulators

I want to introduce you to our synchronous buck regulators, ISL85003 and ISL85003A with an input voltage of 4.5 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 4 X 3 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 over current, over temperature, over voltage, 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 (12Vin in CCM)

This graph shows the efficiency vs. load of the ISL85003 for 12Vin 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 (12Vin 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 12Vin 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.


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