Introduction to the ZL8801 dual phase digital DC/DC controller.


Hi, my name is Brandon Howell, I handle technical marketing with Renesas, and I am here to introduce the ZL8801. The ZL8801 is a two-phase fully digital power controller. It's part of our fourth generation of fully digital controllers and uses charged mode control.

Here is a block diagram of the ZL8801. The ZL8801, as I mentioned is a two-phase controller. It has PWM outputs for driving power stages. In this case, I am showing the ISL99140, our latest 40A power stage. Going over some of the major features of the ZL8801. We have a v drive output for providing 5V bias to the power stage. PWM output for driving the power stage. Direct voltage feedback. All the compensation is done internally, using our charge mode control. A PMBus interface for configuration, control and telemetry. For telemetry, you can measure the input voltage, the input current, the output voltage, the output current, the duty cycle, the temperature as well as configure the device.

The ZL8801 supports current share. With current share configurations, you can have up to four controllers for up to a eight-phase design. Current shares handle via proprietary DDC bus and we will go over that in details in a later video. Now lets head to the lab and look at the ZL8801 eval boards and our PowerNavigator software.

So here I have got both the two-phase and the four-phase board. The two-phase board's here in green. The four-phase board is here in red. As I mentioned, we're going to focus on the two-phase board for this video and we can catch up on the four-phase board in a separate video.

Walking through the major aspects of the two-phase board, I got the ZL8801 controller in the center of the board. I've got my DrMOS power stages, in this case ISL99140. My output inductors, my output capacitors. I've got input terminals for my input voltage. Output terminals for my output voltage. And I have a USB to PMBus adapter. This allows us to communicate with the ZL8801, via a PMBus interface and our PowerNavigator software which runs on our windows GUI.

As you can see from the eval board, the controller itself does not require very many external components. We have some decoupling capacitors. There is a couple resisters to set the PMBus address and the output voltage. That's really it. Because we are a fully digital solution, all the compensation and all the parameters are set inside the device. So because of that we have a very limited number of external components. Very simple two-phase design, yet it's high performance and very easy to adjust. So now lets connect this board to our PowerNavigator software and look at the telemetry, look at margining and basic device operation.

And now lets launch PowerNavigator and interface with the ZL8801 eval board. So when PowerNavigator first comes up it'll automatically scan for any eval boards connected to the computer. It found the ZL8801 eval board at address 30. So I'm going to go ahead and click start, and then as soon as I click start the automatically downloads all the settings and now we are connected to the ZL8801 eval board. So in the center part of the screen I have the power map, which shows the actual ZL8801 board and then on the monitor view tab, I've got all the telemetry. So I am reading the output voltage, the output current, the input voltage, the driver voltage, the temperature, duty cycles, switching frequency, all in real time.

So I have the eval board configured for a 12V in to a 1.2V output. I'm going to go ahead and turn on the output. As soon as I do the output voltage now reads 1.2V. I've got no load on the output so the output current is approximately 0V. And I'm still reading the input voltage and the voltage monitor. Now I have the eval board connected to an electronic load and with the load I can put a load in the output. So I am going to go ahead and load down the output. I just added a to the output and as you can see the PowerNavigator software is reading back 22A. The output voltage remains constant at 1.2V.

Using our software I can also change the output voltage. For example, I can margin up I can margin down. If I do that, I will now margin high, so I margined high to 1.4V. Go back to standard, 1.2V and then I can margin low and I will margin low down to 1V. So as you can see, evaluating the ZL8801 eval board with out PowerNavigator software is very easy. Using the software you can look at the input voltage, the output voltage, the output current, the supply temperature, basically all the telemetry in real time. When it comes time to build your own system the same software can be used to interface with your actual ZL8801 design.

For our eval boards, please see the Renesas website and again we have these ZL8801 two-phase board and a four-phase board as well.