Piet Wessels has been the driving force behind NXP’s (and formerly Philips’) SOI-enabled high-voltage business ever since it first began.
Advanced Substrate News: 10 years ago this spring, NXP (then Philips), announced its EZ-HV SOI technology for applications in the 60 to 650V range. What sorts of products has it been used for? How effective is it in lowering power consumption?
Piet Wessels: We use EZ-HV for products in the power supply and lighting product domains. EZ-HV is ideal for use as IC process with on-chip power devices with a handling cabability up to 20W and switching controllers that need isolated high side drive capability (bridge topologies). Typical products we are using EZ-HV for are Switched Mode Power Supply (SMPS) regulators like the STARplug range, HID lamp drivers and integrated CFL lamp drivers.
Power consumption is important in two main categories: standby or zero load performance (applications in standby mode, or adapters plugged into the mains socket without the cellphone connected, or cell phone fully charged) and efficiency over the full load range.
For ultra high efficency power supplies and lamp drive applications we use resonanting or bridge converters that bring the conversion efficiency >90%. For low power saving modes we employ switch principles that minimize the switching losses. Biasing of the internal IC circuits (switching off those circuits that are not needed) can result in ultra low “idle” modes (<10µA IC supply).
ASN: In 1998, you announced ABCD, an SOI Smart Power process for applications in the 12 to 60V range. It was the first thin-film SOI technology used in high-volume consumer applications. Again, what sorts of products has it been used for? How effective is it in lowering power consumption?
PW: Same as above. Specifically, we use ABCD for high-density smart control. With the increased density versus bulk processes we can integrate more advanced features (different switching modes) that enable maximum efficiency of power converters over all load conditions.
ASN: When does NXP turn to SOI for lowering power consumption? Are there other SOI process besides EZ-HV and ABCD?
PW: EZ-HV and ABCD are currently the SOI processes we have. There are more process variants and there is a roadmap to develop the processes to higher densities and higher breakdown voltages. The SOI process is our defacto standard process for future SMPS and Lighting products. The reason for using SOI is ease of design, robustness in the application, density of the integrated circuits, capability to go more easily to higher switching frequencies, higher operation temperature capability and lower IC current consumption.
ASN: How important is lowering power consumption for your customers?
PW: Demands for low power consumption are extremely visible in no-load or standby performance of power converters. For instance in power supplies and adapter applications there is a current trend to actively bring down this consumption to <30mW.
With conventional, non-SOI technologies and no optimized IC designs, this is the level that is consumed by the IC already: losses in the rest of the applications would end up causing an overall consumption level that fails to meet the requirements. SOI processes are an important technology to realise these extremely low power demands.
ASN: In addition to lowering power, are there other “green” aspects of SOI that you or your customers are leveraging?
PW: The key aspect of SOI is that it is a very robust process. Reverse biasing of the circuits does not result in latchup situations, which means in some (noisy) environments that fewer external components are needed to ‘clean’ the signal applied to the IC. A very good example is the ignition of HID lamps where the lamp causes an ignition spike. Extensive signal conditioning needs to be done if conventional ICs are applied to prevent malfuntioning.
The combination of robustness and higher on-chip temperature capability enable a higher reliability and lifetime of the end products. This in essence leads to lower waste produced by malfunctioning products.
ASN: Do you have an idea of how many chips you’ve built on SOI since you first started using it?
PW: Probably close to 50. Note that SOI can also be used in combination with other technologies in a mult-chip product. For the automotive industry alone, we recently sold our 2-billionth transceiver.
ASN: Do you see SOI’s role in saving power increasing?
PW: In all our products we see an essential role for SOI. All our products are by definition positioned in the energy saving or high effiency domains.
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