Texas Instruments CSD17578Q3AT

Overview

CSD17578Q3AT from Texas Instruments is a 30 V, 6.3 mΩ N-channel NexFET™ power MOSFET in an 8-pin SON 3.3 mm × 3.3 mm package, optimized as a control FET in synchronous buck converters for networking, telecom, and computing systems, with 7.9 nC total gate charge at 4.5 V and avalanche rating for robustness.

For engineers reviewing the CSD17578Q3AT datasheet, CSD17578Q3AT pinout, CSD17578Q3AT application, or CSD17578Q3AT equivalent, key selection criteria include R_DS(on) at 4.5 V (8.2 mΩ), thermal resistance (R_θJC = 4.2 °C/W), Q_gd/Q_g ratio (1.7/7.9 nC), SOA compliance up to 142 A pulsed drain current, and MSL-1 reflow compatibility.

Technical Context

This device employs a silicon-limited 54 A continuous drain current architecture with low gate charge asymmetry (Q_gd = 1.7 nC, Q_gs = 3.3 nC) to minimize switching losses in high-frequency point-of-load converters. Its 30 V V_DS rating and 1.5 V V_GS(th) enable direct drive from 3.3 V or 5 V controllers without level shifting.

The SON 3.3 mm × 3.3 mm package integrates an exposed thermal pad soldered to PCB copper for 4.2 °C/W junction-to-case conduction, supporting >37 W power dissipation at T_C = 25 °C. Avalanche energy rating of 24 mJ (I_D = 22 A, L = 0.1 mH) ensures reliability under unclamped inductive switching.

Key Specifications

Pinout & Package

Package: SON 3.3 mm × 3.3 mm (VSONP/DNH), 8-pin, exposed thermal pad (pin 9 not electrically connected; pad must be soldered for thermal performance).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar N-channel power MOSFET applications.

Compared with CSD17578Q3AT, CSD17577Q3A trades higher gate charge for lower R_DS(on), while DMN3025LFG-7 offers lower on-resistance but lacks avalanche ruggedness-making CSD17578Q3AT optimal for balanced efficiency, reliability, and controller compatibility in telecom and server POL designs.

Availability

CSD17578Q3AT is available at Aetrix Electronics and suitable for telecom point-of-load converters, server VRM high-side switching, and networking ASIC power rails requiring stable component supply, full MSL-1 reflow compliance, and long-term industrial lifecycle support.

Supply support for CSD17578Q3AT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and communications markets since 1930.

The CSD17578Q3AT belongs to TI's NexFET™ power MOSFET product line, engineered specifically for high-frequency, high-efficiency DC/DC conversion in space- and thermally-constrained infrastructure equipment.

FAQ

What is the maximum continuous drain current for CSD17578Q3AT at 125°C case temperature?

The CSD17578Q3AT supports 14 A continuous drain current at T_C = 125 °C, as specified in the Absolute Maximum Ratings table. This derated value reflects thermal limitations of the SON 3.3 mm × 3.3 mm package under elevated ambient conditions and ensures safe operation within its 150 °C maximum junction temperature limit. The CSD17578Q3AT maintains stable R_DS(on) performance across this range due to its low thermal resistance (R_θJC = 4.2 °C/W).

Does CSD17578Q3AT require a gate resistor for typical synchronous buck operation?

The CSD17578Q3AT does not mandate an external gate resistor for basic functionality, but a 1–5 Ω resistor is recommended to dampen ringing and control dV/dt during switching transitions. Its low Q_g (7.9 nC) and Q_gd (1.7 nC) make it sensitive to layout-induced oscillation; TI's SLPA005 application note specifies optimal gate routing practices. The CSD17578Q3AT gate threshold (1.5 V) ensures clean turn-on with standard 3.3 V or 5 V controllers without unintended conduction.

How is the thermal pad of CSD17578Q3AT connected on the PCB?

The exposed thermal pad of the CSD17578Q3AT must be soldered directly to a solid copper pour on the PCB, typically connected to the source net or system ground for both thermal and electrical integrity. TI's SLUA271 application report recommends a minimum 1-inch² 2-oz copper area with 4–8 thermal vias (0.3 mm diameter) to inner ground planes. Failure to solder the pad results in degraded R_θJC performance and potential thermal runaway-the CSD17578Q3AT relies on this pad for >80% of its heat dissipation.

Is CSD17578Q3AT suitable for use as a synchronous rectifier FET?

No, the CSD17578Q3AT is optimized as a control (high-side) FET-not a synchronous rectifier. Its body diode forward voltage (V_SD = 0.8–1.0 V) and reverse recovery characteristics (Q_rr = 4.4 nC, t_rr = 6 ns) are not optimized for low-loss freewheeling. For synchronous rectification, TI recommends complementary devices like CSD17579Q3A (low-side variant). The CSD17578Q3AT's low Q_gd/Q_g ratio and 4.5 V drive capability are specifically tuned for fast, low-loss turn-on in the control position.

What is the gate-to-source leakage current specification for CSD17578Q3AT?

The CSD17578Q3AT specifies a maximum gate-to-source leakage current (I_GSS) of 100 nA at V_GS = 20 V and T_A = 25 °C, per the Electrical Characteristics table. This low leakage ensures minimal quiescent power draw in always-on control circuits and supports stable gate biasing over temperature. The CSD17578Q3AT's oxide quality and process control maintain this specification across its –55 °C to 150 °C operating junction range without degradation.