USB Power Delivery: A New USB Power Delivery 3.0 Controller from Dialog Semiconductor

January 02, 2018 by Nick Davis

Dialog Semiconductor introduces their new USB power delivery controller that handles interface communications between a power adapter and a mobile device.

Dialog Semiconductor introduces their new USB power delivery controller that handles interface communications between a power adapter and a mobile device.

Dialog Semiconductor, a fabless semiconductor manufacturing company known for its ASICs (application-specific integrated circuits) and mixed-signal ICs, recently announced their new iW657P, which is a USB power delivery (PD) controller. It’s compatible with the USB PD 3.0 Programmable Power Supply (PPS) protocol and Qualcomm’s Quick Charge 4+ protocol.


Figure 1. Pinout of the iW657P; USB power delivery 3.0 controller. Image taken from the product summary (PDF).

Supports USB PD 3.0 and PPS

According to its product summary, this USB power delivery IC controls the communications between a power adapter and a mobile device. In other words, this controller allows the mobile device to alter the VBUS voltage—which is generated by the power adapter—from the default 5V, and also to modify the power adapter's maximum current limitation.

Unfortunately, besides the short list that Dialog Semiconductor has provided regarding the features related to USB 3.0 and PPS (see the image below), the PPS support is a bit nebulous to me because 1) I neither own nor have designed any USB PD 3.0 or PPS-compatible devices and 2) Dialog does not elaborate on exactly what the benefits and features are when using USB PD 3.0 or PPS. A bit more information on the technical benefits of using USB PD 3.0 and/or PPS would be helpful.


Figure 2. Short list of what's gained by using USB 3.0 and PPS, from the product summary (PDF).


So if you're a novice in the arena of designing with USB 3.0 and/or PPS, you'll either have to look elsewhere (such as IC datasheets from other manufacturers, or by asking Google) or you'll have to wait until the iW657P product summary document has been updated—after all it's still only a preliminary document with a revision of 0.3—and hope that it provides a better explanation.

USB Type-C Connector

By incorporating the iW657P into your power adapter design, you'll be able to use the advanced USB Type-C connector technology features that make use of the USB Type-C CC1 and CC2 pins. These pins are used for mobile device attach and detach detection as well as for providing the VCONN support for Electronically Marked Cable rated current reading. If you don't know what "Electronically Marked Cable" means, don't bother looking in the iW657P product release document because you won't find much there.

According to the Mouser Electronics article, The Three "C's" of USB Type-C: Connectors, Controllers and Cables, "Electronically marked cables include circuitry to determine the characteristic of the cable (current rating, performance, vendor ID). They are active cables and require a power source, either using Vconn, Vbus or another source." Although this "active cable" method is a bit complicated, it seems to be a logical approach to achieving increased power transfer efficiencies.

Secondary Side "Talks" with Primary Side in AC/DC Power Supplies

When the iW657P resides on the secondary side of an AC/DC power supply and it's paired with one of Dialog's RapidCharge controllers (such as the iW1781 or the iW1791), which would reside on the primary side of the AC/DC power supply, the iW657P "tells" the RapidCharge controller—via a single optocoupler—what voltage and current settings it should use (see image below). Such settings include:

  • output voltage levels
  • output current limits
  • output undervoltage and overvoltage settings
  • fault and reset signals


Figure 3. iW657P (on secondary side) connected to iW1791 (on primary side) via an optocoupler. Schematic taken from the product summary (PDF).

Ordering Information, Additional Part Numbers, and Some Missing Sections

When you're ready to buy an iW657P USB power delivery IC, Dialog Semiconductor has made the ordering process rather easy by means of section 7 (Ordering Information) in the product summary (see image below). This section quickly shows the various iW657P ordering options available, along with their corresponding part numbers. And, if you don't see the IC option(s) that you need, it would be worth your while to contact Dialog to see what they can do for you because, according to Note 1, additional part numbers may be available.


Figure 4. iW657P ordering information, from the product summary (PDF).


Finally, you may notice that while section 11.1 (Part Number Code Description) provides details on the part numbering scheme, you may also notice that sections 8–10 and 11.0 are missing. Yes, it's a small documentation goof, but it may be an embarrassing one nonetheless to certain folks at Dialog.

Have you had a chance to use this new USB power delivery controller IC from Dialog Semiconductor? If so, leave a comment and tell us about your experiences.