SUB85N03-04P MOSFET: Comprehensive Datasheet & D2PAK Report

9 February 2026 0

SUB85N03-04P MOSFET: Comprehensive Datasheet & D2PAK Report

Technical Analysis and Design Implementation Guide

Introduction — Point: The SUB85N03-04P is a 30 V, high-current N-channel MOSFET commonly supplied in D2PAK for medium-power switching and distribution tasks.

Evidence: The official datasheet lists a 30 V V(BR)DSS rating, an 85 A continuous current class, and a 175 °C maximum junction rating.

Explanation: These headline values position the device for 12 V rail switching, synchronous buck outputs, and motor-drive half-bridges where board thermal design and switching losses determine usable current.

Introduction — Point: Engineers need both static and dynamic numbers to choose and mount the device.

Evidence: Datasheet figures for rDS(on), gate charge (Qg), and capacitances provide the starting point for conduction loss and driver sizing.

Explanation: Reading those numbers with their test conditions (VGS, Tj, ID) lets designers normalize rDS(on) vs. temperature and budget switching loss for gate-driver selection and copper area planning.

Product Overview & Key Specifications

SUB85N03-04P MOSFET Analysis

Quick specs at a glance

Parameter Value (typ./max) Visualization / Note
V(BR)DSS 30 V
VGS = 0 V
Continuous current 85 A
Package/class rating
Typical rDS(on) ≈6.5 mΩ @ VGS=10 V; Low conduction loss
Max Temp (Tj) 175 °C High reliability margin

Analysis: The table collects headline numbers for comparison. Use these figures to screen parts by voltage class and on-resistance before performing detailed thermal analysis.

Typical applications and suitability

Point: Applications include synchronous buck converters, motor drivers, battery protection, and automotive 12 V distribution. Evidence: The 30 V rating and high continuous current class suit common 12 V systems and pulsed motor currents. Explanation: Match expected VDS spikes and switching frequency to the device's Safe Operating Area (SOA).

Electrical Characteristics & Performance

Static Characteristics

VBR, VGS(th), rDS(on), leakage: Define conduction and off-state behavior. Comparing rDS(on) at 25 °C and 100 °C is critical to estimate real-world conduction loss. Normalizing per datasheet curves allows designers to predict headroom for SOA limits during high-temperature operation.

Dynamic Behavior

Gate charge, switching times: Dynamic numbers determine driver choice. Use Qg and frequency to approximate driver energy (0.5·VDS·Qg·f). Bench verify turn-on/off captures to account for Miller plateau and dv/dt effects that influence EMI and efficiency.

Thermal & Packaging (D2PAK)

D2PAK Best Practices: Cooling depends heavily on PCB copper. Implement large thermal pours and use multiple vias beneath the tab to inner layers.

Reliability: Absolute maximums (VDS max, TJ max) must be derated. Expect rDS(on) to rise with temperature; validate heavy-pulse SOA with thermal imaging.

Design & Test Guide

  • Gate Drive Layout: Choose VGS ≈10 V for low rDS(on). Keep gate/source loops short to minimize ringing.
  • Loss Budgeting: Conduction loss ≈ I²·rDS(on). At 40 A continuous, Pd_cond ≈ 135 W (example). Heavy thermal spreading is mandatory.

Alternatives & Lifecycle Considerations

Equivalents: When identifying substitutes, use a decision matrix weighting thermals, Qg, and price. Equivalents must match V(BR)DSS and package thermal resistance.

Procurement: Record lot traceability and maintain an approved-alternatives list. Require suppliers to confirm lifecycle status to reduce redesign risks.

Summary

The SUB85N03-04P is a robust 30 V D2PAK MOSFET optimized for 12 V systems. Engineers must prioritize realistic thermal testing and derating rules before production sign-off.

Selection Axis

Prioritize rDS(on) at practical VGS and elevated Tj.

Switching Impact

Qg and Coss dictate driver sizing and EMI control.

Thermal Practice

Optimize tab copper and measure θJA with thermal imaging.

Common Questions & Answers

What are the essential SUB85N03-04P MOSFET test steps before qualification? +
Perform rDS(on) vs. Tj sweeps, pulsed ID/SOA tests, switching waveform captures at intended VDS and load, and thermal imaging during sustained pulses. Record solder joint integrity after thermal cycling and run power-cycle tests to validate long-term stability.
How should I size a gate driver for SUB85N03-04P? +
Dimension driver peak current to charge Qg within your target transition time (I ≈ Qg / tr). Balance gate resistor to limit dv/dt and ringing while keeping switching loss acceptable; validate with scope captures and adjust resistor or snubbers to control overshoot and EMI.
How do I derate SUB85N03-04P for continuous operation on a PCB? +
Calculate Pd from I²·rDS(on) with Tj correction, add switching loss, and divide by measured θJA to estimate ΔTj. Ensure Tj stays below datasheet TJ max with margin; reduce continuous current, increase copper area, or add external heatsinking if required. Validate with thermal imaging under worst-case duty.