TIP120 vs IRLZ44N Pinout & Specs - MegaSquirt PWM Idle Valve Drive Schematic

This document is a composite reference image comparing two transistor options, the TIP120 NPN Darlington transistor and the IRLZ44N N-channel power MOSFET, alongside a solenoid/spare drive schematic (typical of MegaSquirt/MSEXTRA idle valve output circuits). The left panel, sourced from www.componentsinfo.com, shows the TIP120 in a TO-220 package with pinout (1 Base, 2 Collector, 3 Emitter), its internal Darlington circuit, and its schematic symbol. The center panel shows the IRLZ44N in a TO-220AB package with key ratings: V_DSS = 55V, R_DS(on) = 0.022Ω, and I_D = 47A, plus its MOSFET symbol (G, D, S). The right panel is a 'Solenoid/Spare Drive' schematic showing an Idle-1 input through R19 (1K) driving Q4 (ZTX450) with Q20 (2N3904BU), R39 (1-1/2W), and D8 (22V 1W zener) leading to an IDL output. A note states that for installs with a normal PWM idle valve, D8 and Q20 should be omitted, Q4 replaced with a TIP122, and a 1N4001 installed to 12V, per MSEXTRA manuals. The document helps a builder choose and wire output transistors for a PWM idle valve drive circuit.