The ISL95338 bidirectional, buck-boost voltage regulator provides buck-boost voltage regulation and protection features. Intersil's advanced R3™ Technology is used to provide high light-load efficiency, fast transient response, and seamless transitions between discontinuous and continuous conduction modes.


Bidirectional Buck-Boost Voltage Regulator for USB Power Delivery

Welcome to today’s training on the ISL95338, bidirectional buck‐boost voltage regulator for USB power delivery.

ISL95338: Bidirectional Buck-Boost Voltage Regulator

Introducing the industry’s first bidirectional, buck‐boost voltage regulator, the ISL95338, that provides buck‐boost voltage regulation and protection features. Intersil’s advanced R3™ Technology is used to provide high light‐load efficiency, fast transient response, and seamless transitions between discontinuous and continuous conduction modes.

The ISL95338 takes input power from a wide range of DC power sources (conventional AC/DC adapters, USB‐PD ports, travel adapters, etc.) and safely converts it to a regulated voltage up to 24V. The ISL95338 can also convert a wide range of DC power sources connected at its output (system side) to a regulated voltage to its input (ADP side). This bidirectional buck‐boost regulation feature makes its applications very flexible.

The ISL95338 includes various system operation functions such as forward mode enable, reverse mode enable, programmable soft‐start time, and adjustable output voltage in both the forward direction and reverse direction.

The protection functionalities include OCP, OVP, UVP, OTP, etc.

The ISL95338 has serial communication through SMBus/I2C that allows programming of many critical parameters to deliver a customized solution. These programming parameters include, but are not limited to, output current limit, input current limit, and output voltage setting.

The ISL95338 is available in a 32‐lead, 4mm x 4mm TQFN package. This is an ideal solution for any customer looking to implement USB power delivery in any end devices with USB Type‐C ports.

ISL95338 Bidirectional Buck-Boost VR

This slide shows each of the operation modes that the ISL95338 is capable of: Forward Buck, Forward Buck‐Boost, Forward Boost, Reverse Buck, Reverse Buck‐Boost, and Reverse Boost modes. It regulates any input voltage to programmable output voltage as desired, making it ideal for USB power delivery applications.

Bidirectional BB VR Opportunities: No Battery Application

Here are some ideas for applications that could use the ISL95338. Basically, any application where USB power is needed. The one exception is applications for battery charging. For a battery charging application, we have the ISL9238 USB‐C buck‐boost battery charger.

Examples applications include a hub device that connects to a TV, a monitor or a smartphone, audio devices, docking stations, and Flash drives via USB‐C connector and cable.

Identifying Buck-Boost Charger Opportunities

Here is an example application for the ISL9238 buck‐boost charger mentioned in the previous slide. Notice in this application that there are a set of batteries that need to be charged.

Multiple Input Power Sources

We will now look at three different use cases to show you how the buck‐boost voltage regulator can be designed for USB‐PD, and still stay at low cost and still compliant to USB‐PD 3.0 spec.

Case 1 (Dual USB Type-C)

The first case is when there are two USB‐C input sources. Here, we put a ISL95338 for each of the Type‐C ports, while we use a low cost charger, the ISL95521A, to charge the battery. This enables a low cost, automatic power source selection both forward and reverse OTG, turbo charging of the battery, and extends the system power rating with two input power sources. It also eliminates two back‐to‐back P‐channel FETs for each Type‐C port.

Case 2 (Normal Adapter + USB Type-C)

In Case 2, the solution can handle both normal adapter and USB Type‐C input as easy as you can see here.

Case 3 (Normal Adapter + 2 x USB Type-C)

Case 3 shows our solution is capable of handling any type of input source without an issue. You could even parallel up to four ISL95338s to support four USB Type‐C ports input and reverse OTG up to 20V. The normal adapter can also be the power source for reverse OTG operation to multiple USB‐C ports simultaneously.

ISL95338 Evaluation Board

The orderable part number for the ISL95338 evaluation board is ISL95338EVAL1Z. The board has jumpers and switches to configure it for either forward or reverse modes. Using the accompanying GUI and the on‐board USB to SMBus converter, the user has access to all the registers and therefore the ability to test all the features of the ISL95338 such as programmable bidirectional soft‐start time, bidirectional output voltage, maximum output current, and bypass mode enable/disable in both directions.

ISL95338 Available Tools

Samples and evaluation boards are in stock and orderable. Datasheets, user's guide, schematic/design files and a white paper are all available online.


To summarize, the ISL95338 is the industry’s only single chip solution.

It’s the first bidirectional buck‐boost voltage regulator ideal for USB‐PD applications. Intersil already has many proven success stories and combined with Renesas solutions, we are the only reliable total solution provider for these types of applications on the market today.