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Littelfuse p-channel energy MOSFETs, though much less famend than their broadly used n-channel counterparts, have historically served a restricted vary of purposes. Nevertheless, with the growing demand for low-voltage (LV) purposes, the scope of p-channel energy MOSFETs has been expanded. The simplicity of making use of Littelfuse p-channel options for high-side (HS) purposes makes them extra enticing for LV inverters (< 120 V) and non-isolated point-of-load options. The convenience of driving an HS p-channel MOSFET with out the necessity for a cost pump or further voltage supply leads to simplified designal, house financial savings, lowered half rely and value effectivity.
This text makes a primary comparability of n-channel and p-channel energy MOSFETs, introduces Littelfuse’s p-channel energy MOSFETs, after which explores their goal purposes.
A comparative evaluation of n-channel and p-channel energy MOSFETs
To realize the identical on-state resistance RDS(on) because the n-channel sort MOSFET, the p-channel requires a 2 to 3-times bigger die measurement. Subsequently, in high-current purposes, the place low conduction losses are essential, giant die p-channel MOSFETs with very low RDS(on) are suboptimal. Whereas the bigger chip measurement of the p-channel gadget gives improved thermal efficiency, it displays bigger intrinsic capacitances and thus increased switching losses. This disadvantage considerably impacts total system price, effectivity, and thermal administration when the system operates at a excessive switching frequency.
Fig. 1: Cross sections of an n- and p-channel energy MOSFETs with their symbols
In low-frequency purposes with important conduction losses, a p-channel MOSFET ought to match the RDS(on) of an n-channel MOSFET, requiring a bigger chip space. Conversely, in high-frequency purposes prioritizing switching losses, a p-channel MOSFET ought to align with the full gate costs of an n-channel counterpart, typically having an analogous chip measurement however a decrease present ranking. Subsequently, choosing the proper p-channel MOSFET calls for cautious consideration of gadget RDS(on) and gate cost (Qg) specs together with the thermal efficiency.
Littelfuse p-channel energy MOSFETs
Littelfuse gives a variety of business certified p-channel energy MOSFETs with the very best voltage class, lowest RDS(on) and Qg, excessive avalanche vitality ranking, glorious switching efficiency and superior protected working space (SOA) with best-in-class efficiency in each commonplace industrial and distinctive remoted packages. Littelfuse p-channel energy MOSFETs retain the important options of comparable n-channel energy MOSFETs similar to quick switching, environment friendly gate-voltage management, and glorious temperature stability.
Fig. 2: Littelfuse p-channel energy MOSFET portfolio
Fig. 2 presents the important thing highlights of p-channel energy MOSFETs provided by Littelfuse. Normal P and PolarP
planar gadgets can be found with voltage rankings from -100 V to -600 V and present rankings from -2 A to -170 A. PolarP gives optimized cell construction with low area-specific on-state resistance and improved switching efficiency, whereas Normal P advantages from a greater SOA efficiency. Trench P using a extra dense trench gate cell construction gives very low RDS(on), low gate cost, quick physique diode and quicker switching with gadget voltages starting from -50 V to -200 V and currents from -10 A to -210 A. The most recent addition to the portfolio is IXTY2P50PA (-500 V, -2 A, 4.2 Ω) which is Littelfuse’s first automotive grade p-channel energy MOSFET for automotive purposes.
Functions for Littelfuse p-channel energy MOSFETs
N-channel MOSFETs are usually used within the energy stage in typical half-bridge (HB) purposes, . Nevertheless, n-channel HS switches necessitate a bootstrap circuit to generate a gate voltage that’s floating just about the supply of the HS MOSFET or an remoted energy provide to activate as proven in Fig. 3a). Therefore, the benefit of utilizing n-channel gadgets comes at the price of elevated complexity in gate driver design resulting in extra design effort and better house utilization. Fig. 3 illustrates the distinction between circuits utilizing complementary MOSFETs and people utilizing n-channel MOSFETs. When a p-channel MOSFET is used because the HS swap on this configuration as depicted in Fig. 3b), it might enormously simplify the motive force design. A cost pump that drives the HS swap may very well be eliminated and the p-channel MOSFET could be simply managed by the MCU by way of a easy degree shifter. This reduces design effort and half quantity rely leading to a cost-efficient design that makes use of house effectively.
Fig. 3: Simplification of the HS driver in HB software from a) n-channel MOSFET to b) p-channel MOSFET as HS swap
Reverse polarity safety
Reverse polarity safety is a security measure inside programs to stop potential fireplace hazards and damages brought on by a reverse connection of the facility supply. Fig. 4a) exhibits the reverse polarity safety carried out utilizing a p-channel energy MOSFET. When the battery is appropriately linked, the intrinsic physique diode conducts till the MOSFET channel is activated. Within the occasion of a reverse connection of the battery, the physique diode is reverse-biased, with the gate and supply on the identical potential, thereby turning off the p-channel MOSFET. A Zener diode clamps the gate voltage of the p-channel MOSFET, defending it in case of excessively excessive voltage ranges.
Fig. 4: a) Reverse polarity safety and b) Load swap utilizing p-channel energy MOSFET
Load swap
Load switches join or disconnect a voltage rail to a particular load providing a cheap and easy method for a system to effectively handle energy. Fig. 4b) demonstrates a circuit utilizing a p-channel energy MOSFET for a load swap. This circuit is pushed by a logic allow (EN) sign controlling the p-channel load swap by way of a small-signal n-channel MOSFET Q1. When EN is low, Q1 is off, and the p-channel gate is pulled as much as VBAT. Conversely, when EN is excessive, Q1 prompts, grounding the p-channel gate, and turning on the load swap. If VBAT exceeds the p-channel MOSFET’s threshold voltage, it might activate when EN is excessive, eliminating the necessity for a further voltage supply to bias the gate, which is important for n-channel MOSFETs. The collection resistor is required to restrict the present and a Zener Diode to clamp the gate voltage to a most worth.
DC-DC converters
Fig. 5: Low energy a) synchronous buck and b) synchronous enhance converter utilizing complementary MOSFETs
Conclusion
With the event of contemporary LV purposes, Littelfuse’s p-channel energy MOSFETs show their versatility in assembly the evolving wants of at the moment’s energy electronics. Using Littelfuse’s complete vary of p-channel MOSFETs offers designers with benefits similar to simplified, extra dependable, and optimized circuit design in industrial and automotive purposes. To realize optimum efficiency for particular purposes, designers should assess the trade-off between RDS(on) and Qg when choosing a p-channel energy MOSFET.
Creator: Sachin Shridhar Paradkar, Littelfuse
The publish Exploring The Options And Functions Of Littelfuse P-Channel MOSFETs appeared first on Electronics For You.
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