Texas Instruments LM26420Q1XSQX/NOPB

Overview

LM26420Q1XSQX/NOPB from Texas Instruments is a dual-channel synchronous buck DC/DC converter delivering 2 A per channel at 2.5 V and 1.2 V outputs, operating from 3 V to 5.5 V input, with 2.2 MHz fixed switching frequency and integrated 75-mΩ PMOS / 50-mΩ NMOS power switches - used for FPGA core/I/O rail generation in space-constrained industrial and automotive infotainment systems.

For engineers reviewing the LM26420Q1XSQX/NOPB datasheet, LM26420Q1XSQX/NOPB pinout, LM26420Q1XSQX/NOPB application, or LM26420Q1XSQX/NOPB equivalent, key selection considerations include independent precision enable (1.04 V threshold), 180° out-of-phase operation for reduced input ripple, ±1.5% internal 0.8 V reference, thermal shutdown at 165°C, and CISPR25 Class 5 conducted emissions compliance.

Technical Context

The LM26420Q1XSQX/NOPB implements current-mode PWM control with internal compensation and artificial ramp slope for stable regulation across load and line variations. Its dual-channel architecture uses interleaved 180° phase-shifted switching to halve input capacitor RMS current and suppress EMI peaks.

Each channel features independent soft-start (600 µs ramp), overvoltage protection (15% above VREF), undervoltage lockout (2.628 V rising, 2.3 V falling), and cycle-by-cycle current limiting (3.3 A typical). The device supports startup into prebiased outputs and maintains regulation down to 0.8 V output via external resistor divider.

Key Specifications

Pinout & Package

LM26420Q1XSQX/NOPB is packaged in a 20-pin HTSSOP (PWP) with 6.50 mm × 4.40 mm body size and exposed die attach pad (DAP) for enhanced thermal dissipation. Pin 10 is DAP and must be soldered to system ground plane.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-buck regulator applications.

Compared with LM26420Q1YSQX/NOPB, the LM26420Q1XSQX/NOPB trades slightly higher light-load IQ for superior high-frequency EMI performance and smaller passive components; versus TPS54290RGTR, it delivers true dual-rail integration with coordinated control, reducing component count and layout complexity by ~30%.

Availability

LM26420Q1XSQX/NOPB is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial gateways, and high-density storage controllers requiring stable component supply, AEC-Q100 Grade 1 qualification, and long-term production continuity.

Supply support for LM26420Q1XSQX/NOPB 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 leader specializing in analog, embedded processing, and power management technologies, with decades of automotive-grade product development and manufacturing expertise.

The LM26420 product line delivers high-efficiency, EMI-optimized dual buck regulators for space-constrained, safety-conscious applications including automotive ADAS, infotainment, and industrial control systems.

FAQ

What is the switching frequency of the LM26420Q1XSQX/NOPB and how does it affect design?

The LM26420Q1XSQX/NOPB operates at a fixed 2.2 MHz switching frequency. This high frequency enables use of small inductors (typically 0.47–1.0 µH) and low-ESR ceramic capacitors (10–22 µF), significantly reducing solution size and simplifying EMI filter design. It also supports seamless integration into compact PCB layouts common in automotive and portable electronics. The LM26420Q1XSQX/NOPB maintains stable regulation and high efficiency (up to 93%) across its full 3–5.5 V input range.

Does the LM26420Q1XSQX/NOPB support independent power sequencing between its two outputs?

Yes, the LM26420Q1XSQX/NOPB provides fully independent enable (EN1/EN2) and power good (PG1/PG2) signals for each buck channel. This allows precise control over startup order, hold-off timing, and fault response - for example, enabling V_core before V_I/O in an FPGA or shutting down one rail while keeping the other active. Each EN pin has a 1.04 V threshold with 150 mV hysteresis, and each PG pin is an open-drain output requiring an external pull-up resistor. The LM26420Q1XSQX/NOPB supports both ratiometric and staggered start-up modes depending on EN pin configuration.

What thermal performance can be expected from the LM26420Q1XSQX/NOPB in a typical 2-layer PCB layout?

In a standard 2-layer PCB with 1 oz copper and moderate copper pour around the HTSSOP-20 package, the LM26420Q1XSQX/NOPB exhibits a junction-to-ambient thermal resistance (R_θJA) of 38.5°C/W. With both channels delivering 2 A at 90% efficiency (≈2 W total dissipation), junction temperature rise above ambient is approximately 77°C - well within the 125°C maximum operating junction temperature. For sustained full-load operation, adding thermal vias under the DAP and increasing copper area reduces R_θJA to ≤30°C/W. The LM26420Q1XSQX/NOPB includes thermal shutdown at 165°C for fault protection.

How does the LM26420Q1XSQX/NOPB handle startup into a prebiased output?

The LM26420Q1XSQX/NOPB supports controlled startup into prebiased outputs by ramping its internal 0.8 V reference from the existing FB pin voltage rather than from 0 V. This prevents reverse current flow through the bottom FET and avoids output overshoot or instability. The soft-start time remains fixed at ~600 µs regardless of initial bias level. This capability is essential in redundant power systems, hot-swap applications, and systems with multiple power domains sharing common rails. The LM26420Q1XSQX/NOPB implements this behavior without requiring external components or configuration changes.

Is the LM26420Q1XSQX/NOPB qualified for automotive applications and what standards does it meet?

Yes, the LM26420Q1XSQX/NOPB is AEC-Q100 Grade 1 qualified (–40°C to +125°C ambient operation) and designed for automotive infotainment and body electronics. It complies with CISPR25 Class 5 for conducted emissions - the most stringent level for automotive subsystems - eliminating the need for external EMI filters in many implementations. The device includes automotive-grade reliability features including undervoltage lockout with hysteresis, overvoltage protection, thermal shutdown, and robust ESD tolerance (±2000 V HBM, ±750 V CDM). The LM26420Q1XSQX/NOPB is manufactured in TI's ISO/TS 16949-certified facilities.