ISL8202M, ISL8205M 3A/5A Step-Down Power Modules

Added on May 24, 2016

Introducing the power dense, compact power modules ISL8202M and ISL8205M, ideal for battery-operated applications. Intersil demonstrates the selectable light-load efficiency mode and 100% duty cycle LDO mode, which enable better efficiency and lower power consumption at light-load.

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Video Transcript

ISL8202M/05M 3A/5A Single-Channel, High Efficiency DC to DC Step-Down Power Modules

Hello and welcome to Intersil. I'm Eric Pittana, Senior Product Marketing Manager in the industrial power group. And today, I'd like to introduce to you not one but two new devices, part of Intersil's family of fully encapsulated power module: the ISL8202M and ISL8205M. When compared to a traditional implementation of the point of load, a lot of precaution has to be taken into selecting the controller, the FETS, the inductor, the drivers, in order to meet certain performance and size criteria for the point of load being designed.

The ISL8202M and ISL8205M integrate all those components in a small 4.5mm x 7.5mm package reducing the guesswork related to developing a point of load solution. Now immediately, benefits can come to mind. The first one is the compactness of the overall solution increasing to a higher power density, reachable on a PCB board. The second one is the ease of design and use. Only a few components have to be selected to make this part operate. The performance is very predictable, because now all the solution, all the power module has been characterized, and in essence, are less sensitive to component variation and aging.

Finally, with a height of 1.85mm, this power module can easily be mounted on the backside of the PCB board, freeing a valuable space for a top-sided mounted components. For this exercise and this video, we're gonna be using an ISL8205M evaluation board sitting here. We're gonna review some of the specific features and characteristic of the solution. So let's turn it on.

Here on the scope, we have three pieces of information: the input voltage, currently sitting at around 5V, the output voltage, 1.2V, and the switching node underneath. This device supports anywhere from 2.6V to 5.5V input voltage range. The output voltage range can be as low as 0.6V. The evaluation board, as a matter of fact, provides you with an easy setting that selects some of the most common output voltages in use in the electronic industry.

The output current will be set through a classical chroma load. In this case, we are actually, currently running at 5A output, the maximum output current available for the ISL8202 and ISL8205M. Some of the specific features of the part makes it very suitable for battery operated equipment, one of which being the capability of the ISL8205M to be configured to support a light load boosted efficiency mode. It is selectable because some designs prefer to stay with a constant frequency, whereas others, battery operated typically may require to use a variable frequency in order to boost the light load efficiency, meaning below anywhere, below 700mA of output current.

We see here that we are currently running at 3A of output current. I'm gonna switch down to 50mA. One thing that we're observing immediately is that our switching node operates by burst pulses. This is also known as pulse skipping or burst mode in the literature. I can go from one to the other, and we can see that the power will react immediately to a light load condition by halting essentially the switching mode, turning off the bottom FET and essentially allowing the output cap and the output to discharge fully into the load.

Another specific feature of the ISL8205M specifically targeted to the battery operation is the capability of supporting 100% duty cycle, also called LDO mode. In this case, the power module is capable of adjusting its output duty cycle in case the input voltage reaches very close to the output voltage selected. This is typical of a battery voltage, decaying overtime between charges. In this case, we've set the output voltage to 3.3V. We're still running at 5V input. I'm gonna slowly take down the input voltage to reach closer to the 3.3V desired output.

One thing that we can observe is that at a certain point, my switching node has stopped switching essentially, turning on the top FET constantly, and the difference between the input and the output voltage remains constant or about 200mV, in this case. As I keep going down, this delta is going to be maintained for as long as possible until eventually, the part input voltage collapses and the part turns off, because we've hit the undervoltage lock-up situation.