MOSFET ICs Roll in Small Package Formats—a Roundup

Driven by the evolution of smart devices, the demand for smaller ICs is an appetite that sees no end in sight. System designers are faced with the challenge of bringing complex concepts such as artificial intelligence (AI) and machine learning (ML), into the next generation of small electronics.

Serving those needs, this year has seen a number of small MOSFET product announcements that could help designers accommodate size-constrained PCB designs where scaled-down electronics are the priority.

In this article, we round up some MOSFET ICs that push the boundaries of small package sizes.

 

30 V MOSFET in DFN Package

Exemplifying these trends, among Nexperia’s most recent MOSFET offerings is what it claims as the industry's smallest DFN (dual-flat no-leads) packaged MOSFET.

 

Nexperia targets next-gen wearables with tiny DFN-packaged MOSFET. Image used courtesy of Nexperia 

 

Choosing an appropriate MOSFET is a common struggle for electrical designers. Not only do designers have to stick to sizing parameters but the overall IC has to avoid heat dissipation, have low switching losses, consume minimal power, and not give negative feedback to the system. 

DFN packaging allows designers to strategically place circuits directly onto PCBs since they are surface-mounted with no leads. In the current market, DFNs are the smallest MOSFET out there with a standard length of 2 mm. 

Nexperia’s set of DFN0603 MOSFETs are packaged in a 0.63- × 0.33- × 0.25-mm housing. At this size, designers can address PCB layouts with ease while still reaping the benefits of a high-switching MOSFET.

Aside from sizing hurdles, Nexperia also focused on integrating electrostatic discharge (ESD) protection into their latest MOSFET. ESD protection can prevent static electricity from flowing through the IC. In the event of high voltage being introduced to the MOSFET, a static discharge can occur and this would be detrimental to the overall PCB.

Another feature of Nexperia’s DFN MOSFET is the low R_DS(ON) (drain-source on-resistance) that keeps power loss minimal while keeping heat dissipation down, which most power transistors struggle to accomplish. 

 

650 V SiC MOSFET with TO-Leadless Package 

Onsemi is another manufacturer that is scaling things down with one of its latest 650 V Silicon Carbide (SiC) MOSFET, the NTBL045N065SC1. 

SiC devices are the desired route for developers since they tend to be more efficient than silicon.  SiC-based FETs offer a way to lower electromagnetic interference (EMI) when experiencing high frequencies and temperatures, a common struggle for power transistors.

 

The NTBL045N065SC1’s TOLL packaging allows developers to meet power design challenges while maintaining up to a 60% smaller footprint in comparison to non-surface mounted power transistors. Image used courtesy of Onsemi

 

Onsemi’s newest SiC MOSFET is packaged in a TO-Leadless (TOLL) layout. For previous 650V SiC-based products, Onsemi has stuck to double decawatt (D2PAK) packaging for these discrete high-power devices. D2PAK offers 3 to 7 pins for mounting onto PCBs but doesn’t consider the spacing for the internal components like a TOLL arrangement. More information is available in the NTBL045N065SC1 datasheet.

With TOLL packaging, the main objective is to save space on the PCB, and with Onsemi not using D2PAK they will save 30% of PCB area. However, another huge advantage to going TOLL is the thermal performance at 650V.  Reliable even at a max junction temperature of 175°C while adding low inductance, gate noise mitigation, and unphased switching losses.

A unique specification for Onsemi’s TOLL packaged SiC is how it mitigates negative feedback, EMI.  Unlike typical power transistors, this MOSFET is arranged with a Kelvin Source configuration which eliminates negative feedback received at the source lead. This solution holds many advantages but isn’t perfect, one drawback is that designers may need to add a dedicated gate driver IC to combat any voltage spikes.

 

40 V MOSFET Targets Battery Powered Designs

STMicroelectronics (ST) is another developer that was able to scale down its MOSFET device in order to save PCB space. In June, ST announced its latest expansion of 40 V MOSFETs, the STL320N4LF8 and STL325N4LF8AG as a part of the next STripFET F8 Series.

Taking a closer look at the STripFET F8 technology, both 40 V solutions can handle a wide range of applications in small footprints. The STL320N4LF8 is an N-channel enhancement mode MOSFET that decreases energy usage through low R_DS(ON) and high power density. This STripFET is ideal for battery-powered products in computing, telecom, and power conversion.

The STL325N4LF8AG has essentially the same design parameters as the STL320N4LF8 but is geared towards automotive applications. This STripFET model can prevent system failures due to unwanted noise with embedded EMI protection that can prevent spikes from the drain-source voltage. More information is available in the datasheets for the STL325N4LF8AG and the STL320N4LF8.

 

Targeting low voltage automotive applications, the STripFET F8 can handle inrush current and recover faster than any competing IC. Image used courtesy of STMicroelectronics

 

According to ST, the STripFET goes beyond wearables and automotive applications by giving power system engineers the ability to improve the efficiency of motor control topologies. 

Typical motor control switches and relays tend to utilize 3-phase inverters and H-bridge layouts. These topologies carry a lot of negative feedback in the form of EMI starting at the motor which degrades the performance of the overall system. ST’s STripFET F8 offers proper capacitance along with a body diode to ensure extremely low EMI during hard-switching, says ST.

 

Smaller MOSFETs Could Make a Big Impact

By focusing on shrinking down MOSFET packaging, developers like ST, Onsemi, and Nexperia can produce high-power density ICs for the next generation of smartwatches, hearing aids, motor control devices, and power distribution circuits.