Tag Archives: intersil

What is USB Type-C Interface?

All new electronic devices are now coming with the USB-C interface, and this is revolutionizing the way people charge the devices. So far, most electronic devices had the micro-USB type-B connectors. With the USB Type-C connector, it is immaterial what orientation you use for the charging cable—the non-polarized connector goes in either the right side up or upside down. The connecting system is smart enough to figure out the polarity as a part of the negotiation process, and supports bidirectional power flow at a much higher level.

Earlier, the USB connectors handled only the 5 VDC fed into them. The USB-C port can take in the default 5 V, and depending on the plugged in device, raise the port voltage up to 20 V, or any mutually agreed on voltage, and a preconfigured current level. The maximum power delivery you can expect from a USB-C port is 20 V at 5 A or 100 W. This is more than adequate for charging a laptop. No wonder, electronic device manufacturers are opting for incorporating the USB-C into their next-generation products.

With the increasing power delivery through the USB Type-C ports, the computer industry has had to raise the performance requirement of the voltage regulator. Unlike the USB Type-B and the USB Type-A fixed voltage ports, the USB Type-C is a bidirectional port with a variable input, and an output range of 5-20 VDC. This adjustable output voltage feature allows manufacturers of notebooks and other mobile devices to use USB Type-C ports to replace the conventional AC/DC power adapters and USB Type-B and A terminals. Manufacturers are taking advantage of these features and incorporating dual or multiple USB Type-C ports into their devices.

However, using the current system architecture for implementing dual or multiple USB Type-C ports, leads to a complicated situation. It is unable to meet many requirements of the customers. As a solution, Intersil has proposed a new system architecture using the ISL95338 buck-boost type of regulator, and the ISL95521A, which is a combo battery charger. Use of these devices simplifies the design of the USB-C functions and fully supports all features. Applied on the adapter side, manufacturers can implement a programmable power supply, and it offers an adjustable output voltage that matches the USB-C variable input voltage.

In the proposed design, Intersil offers an architecture with two or more ISL95338 devices in parallel. Each of them interfaces a USB Type-C port to the ISL95521A battery charger. As this architecture eliminates several components from the conventional charging circuit, including individual PD controllers, ASGATE and OTG GATEs, it saves manufacturers significant costs. For charging a battery, power is drawn directly from the USB-C input to the ISL95521A, and the multiple ISL95338s offer additional options.

For instance, the user can apply two or more USB-C inputs with different power ratings for charging the battery fast. Therefore, the battery charge power is now higher than that supplied by a single USB-C input power. It also means there is no need for adding external circuitry to determine the different power rating operations of the paralleled ISL95338 voltage regulators.

Rechargeable Battery Packs Benefit From Integrated Battery Pack Monitor

Increasingly, electronic devices are depending on more than one battery unit for deriving power—driving motors require a higher voltage than does the control system. This includes energy storage systems, toys, scooters, e-bikes, handheld power tools, lawn equipment, and vacuum cleaners. So far, battery monitors could only monitor the entire battery pack and not the individual batteries making up the pack. Now, Intersil has developed a battery pack monitor with a difference. Not only can it monitor 3-to-8 cells simultaneously and individually within a pack, it can cater to different battery chemistries as well.

The battery pack monitor from Intersil, the highly integrated ISL94202, enables designers to restrict their design to only two terminals, while accurately monitoring, protecting, and balancing each cell of a rechargeable battery pack, thus ensuring their safe operation and charging.

Acting as a stand-alone protection system for batteries, the ISL94202 has an internal state machine sporting five pre-programmed modes. Apart from accurately balancing and controlling each cell in the battery pack, these modes also protect the entire pack from catastrophic events such as cell voltage over-discharge/ overcharge, short circuit conditions, and hardware faults. Additionally, the ISL94202 conforms to the pack safety requirements of IEC62133, UL2271/72, and UL2054 standards.

Using the ISL94202 does not require an external microcontroller. Designers can directly program the battery pack monitor, which Intersil claims can control the smallest and least expensive battery packs available in the industry. However, the ISL94202 has an I2C serial communication bus, through which it can transfer data such as the state of health, state of charge, and fuel gauge measurements related to the cells to an external microcontroller. The device has a high-side current measurement feature that enables precise fuel gauge status monitoring.

It is easy to interface the ISL94202 to tools or electric motor equipment, as the battery pack monitor integrates high-side FET drive circuitry for charging and discharging—keeping all electronics at ground level reference. The device also has external passive cell-balancing switch controls, which ensure proper cell energy matching, while protecting the cells individually from chronic undercharging. Manufacturing is greatly simplified as the ISL94202 has the capability to withstand hot plug events such as those happening during factory assembly of battery packs.

According to Philip Chesley, a senior vice president with Precision Products at Intersil, customers can expect all the necessary front-end battery features from the ISL94202, against catastrophic pack failures. The innovative high-side FET control can monitor current and cell measurement while delivering a small footprint solution for efficient battery pack designs.

ISL94202 has a temperature sensor interface, power FET control, current sense monitor, and automatic cell balance using a 14-bit ADC, all without needing recourse to an external microcontroller. It can handle cell voltage level shifts of up to 4.8 V per cell, while monitoring for different battery chemistries such as Li-ion FePO4, Li-ion Mn2O4, and Li-ion CoO2.

For cell balancing, the ISL94202 can use external FETs being driven by the internal state machine of the device, or an external microcontroller. Additionally, the ISL94202 covers the operational industrial temperature range of -40°C to +85°C, measures 6X6 mm, and comes in a 48-lead QFN package.

Helping Encapsulated Modules Keep Their Cool

When you encapsulate an active module, you actually cut off air from circulating and removing heat from around the components by the normal process of convection. That forces heat build-up within the active components, including some passive components as well, leading to possible premature failures. Intersil has now mastered the technology of effectively removing heat away from fully-encapsulated modules. Using their unique thermal design, Intersil is able to design very compact encapsulated modules handling up to 50A.

For example, the ISL8240 from Intersil is a 100W analog module, a step-down power supply with single 40A and dual 20A output in the same design. You can parallel up to six of these tiny modules to get a whopping 240A output. Applications involve LTE base stations and data center servers with design architectures built using several FPGAs, ASICs and microprocessors. Only 17x17mm in size, it is extremely difficult to keep the ISL8240 modules cool while delivering full power. Interestingly, Intersil has already announced another module with single 50A and dual 25A module in the same size.

The efficiency of Intersil’s thermal design was evident at a thermal test conducted with the ISL8240 module delivering 40A as output. The fully encapsulated module showed an impressive 99.6°C maximum temperature. Intersil has an evaluation board for users to try their design – ISL8240MEVAL4Z. The tests were conducted using the evaluation board at room temperature without any air flow.

The secret of the Intersil thermal design is a multilayer PC board. The trick is in placing multiple vias strategically to maximize the thermal performance. If this is done correctly, the design need not use any heat sink or fan.

In addition, the IC is mounted thermally on to a copper substrate. This allows attainment of a low thermal resistance of the order of 8.5°C/W. The multilayer board also has two internal copper planes sandwiched in between. These are connected to the top plane with multiple vias, allowing a low thermal resistance design that can remove the excess heat efficiently from the module. The top and bottom layer of the 4-layer board uses 2 oz. Copper, while the inner board layers are made of 1 oz. Copper. Intersil offers Gerber files to speed up your design time.

Intersil makes the PCBs of FR4 grade board material and copper with small additional amounts of solder, nickel and gold. The board uses vias with a finished hole size of 0.012 inches. For making a via, the initial hole drilled is of 0.014 inches. Plating adds a copper wall of 0.001 inches to the hole. Subsequently, the board is plated overall with an ENIG process, adding about 200µ inches of nickel and 5µ inches of gold on to the outer copper surfaces.

If you consider the thermal resistance of one via to that of the copper in the board layers, it will be seen that the via has a much higher thermal impedance for each layer. However, one via occupies only about 1/5000th of a square inch of the board area. The effect of placing N multiple vias in an area is a reduction of the thermal resistance by Nx times.