[In-depth report] Use one power design to adapt to all fast charging protocols! This chip from PI does it

The rapid changes in the current AC/DC power conversion market are obvious to all, especially the endless emergence of various fast charging protocols, which is overwhelming. This is not good news for power supply manufacturers, because they have to provide different power supply products according to the needs of different customers and different products, which is a challenge to the workload of power supply engineers and the supply chain management of manufacturers.

As the name suggests, InnoSwitch3-Pro is an upgraded version of the InnoSwitch3 power IC launched just last year, so it naturally inherits many outstanding features of the previous InnoSwitch3, such as: it can provide a maximum output power of 65W; up to 94% efficiency under various input voltage and load conditions; excellent dynamic characteristics; integrated comprehensive protection features, etc.

^{However, the biggest difference of this power IC is that it has an I2C} interface integrated in the chip , through which the microprocessor can be directly connected to the power IC, and the output voltage and current can be precisely dynamically stepped through the control signal - the voltage step length is 10mV, and the current step length is 50mA - to achieve digital programmable power conversion. With this power design, power engineers can support almost any dynamic fast charging protocol such as USB PD 3.0 + PPS, QC4, SCP, FCP, VOOC, etc., with a suitable microcontroller.

Figure 1 InnoSwitch3 with integrated I2C interface realizes digitally programmable power conversion

At the same time, in addition to the control of output current and voltage, the "digital programmable" feature of InnoSwitch3-Pro is also reflected in the setting of protection functions. Both the response mechanism of the power protection characteristics and the trigger thresholds of various protections can be set externally through software, which greatly increases the design flexibility of power supply design performance. InnoSwitch3-Pro integrates telemetry technology for bus voltage, current and fault reporting, as well as externally settable power supply over-temperature protection point (OTP), input overvoltage/undervoltage (OV/UV) protection point, output overvoltage/undervoltage (OV/UV) protection and short-circuit protection reaction mechanism, which greatly reduces the number of BOM components of complex offline power supplies and greatly simplifies the complexity of power supply design.

Figure 2 InnoSwitch3-Pro system schematic

For power supply manufacturers, the changes brought by InnoSwitch3-Pro may be disruptive. As can be seen from Figure 3, when responding to the needs of various different customers, the traditional power supply production method has to make separate designs for different specifications, prepare BOM stocks for different designs, and produce them separately through multiple production lines; after adopting InnoSwitch3-Pro, a single design, the same BOM, and one production line can flexibly respond to the requirements of various power supply designs. The design using InnoSwitch3-Pro only needs to undergo one safety certification to meet the needs of power supplies with multiple output specifications and characteristics, which greatly saves certification costs. This is unimaginable for traditional power supply design.

Figure 3 InnoSwitch3-Pro changes the traditional power supply production method

It is precisely because of this "flexibility" that the market fulcrum of InnoSwitch3-Pro is not limited to the field of fast charging. In non-charging applications, a single power supply design can achieve multiple output characteristics, which can also achieve better cost-effectiveness. At the same time, the product can be programmed according to the protection characteristics requirements of different regions to meet the power supply design requirements of various regions. Furthermore, once the power supply leaves the factory, if the customer needs to change the output characteristics, the software can also be used on-site to change the output specifications of the power supply or set the protection characteristics, which can meet the end customer's temporary change needs for the power supply in a very timely manner.

As Shyam Dujari, director of product marketing at Power Integrations, says: “The ability to precisely control the output voltage and current of a power supply in different application environments is also very useful for designers of professional applications that require low-volume production, because they can use software to easily configure the output specifications during production or during installation to meet the power needs of different applications.”

In order to enable developers to experience the "bonus" brought by InnoSwitch3-Pro as soon as possible, PI has prepared a series of supporting resources, such as:

• Complete API library for easy object-based programming

• Doxygen program generator , generates high- quality software reference documentation

• Reference designs that work with different microprocessors to accelerate the implementation of customer products and solutions

Figure 4 InnoSwitch3-Pro reference design list