Texas Instruments TPS5420D

Overview

TPS5420D from Texas Instruments is a 2A, wide-input (5.5V–36V), synchronous step-down DC/DC converter with integrated 110mΩ high-side N-channel MOSFET, fixed 500kHz switching frequency, and adjustable output down to 1.22V (±1.5% initial accuracy), used in 12V/24V distributed power systems and industrial audio supplies.

For engineers reviewing the TPS5420D datasheet, TPS5420D pinout, TPS5420D application, or TPS5420D equivalent, key selection considerations include input UVLO threshold (5.3V), ENA enable control (1.3V rising), internal slow-start time (8ms typical), thermal shutdown trip point (135°C), and voltage feed-forward for improved line transient response.

Technical Context

The TPS5420D implements constant-frequency voltage-mode PWM control with integrated voltage feed-forward to maintain stable modulator gain across input voltage variations-enabling consistent loop response and simplified compensation. Its internal type-3 compensation network eliminates external compensation components.

It integrates a bootstrap-recharge diode and supports gate drive via a 0.01μF BOOT–PH capacitor. Protection includes cycle-by-cycle overcurrent limiting (3–5A peak), overvoltage protection (112.5% × VREF), and thermal shutdown with 14°C hysteresis-ensuring robust operation under fault conditions.

Key Specifications

Pinout & Package

TPS5420D is housed in an 8-pin SOIC package (4.9mm × 6mm), optimized for thermal performance on standard PCBs with R_θJA = 75°C/W (custom board) and R_θJB = 55°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down converter applications.

Compared with LM2678-5.0/NOPB, TPS5420D offers adjustable output and enable control in a smaller solution size; versus TPS5430DDAR, it provides lower conduction loss at 2A but less current headroom-making it optimal for cost- and space-sensitive 2A applications.

Availability

TPS5420D is available at Aetrix Electronics and suitable for consumer electronics power supplies, industrial audio amplifiers, and battery charger auxiliary rails requiring stable component supply and long-term manufacturability.

Supply support for TPS5420D 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 expertise in high-reliability power conversion ICs.

The TPS5420D belongs to TI's SWIFT™ family of integrated DC/DC converters-designed specifically for industrial, automotive, and consumer applications demanding high efficiency, small solution size, and robust protection in wide-input-voltage environments.

FAQ

What is the minimum input voltage required for TPS5420D to start switching?

The TPS5420D incorporates an undervoltage lockout (UVLO) circuit with a typical rising threshold of 5.3V and 350mV hysteresis. It will not initiate switching until the VIN pin voltage exceeds 5.3V. Below this level, internal circuits remain inactive and the slow-start sequence is held in reset. The TPS5420D datasheet specifies 5.5V as the recommended minimum operating input voltage to ensure reliable startup across temperature and process variation.

Can TPS5420D be used to generate an output voltage lower than 1.22V?

No, the TPS5420D cannot regulate below its internal voltage reference of 1.221V. This reference sets the minimum feedback voltage at the VSENSE pin; therefore, the lowest achievable output voltage is determined by the resistor divider ratio and is fundamentally limited to ≥1.22V. Attempting to configure for lower outputs results in regulation failure and uncontrolled voltage rise. For sub-1.2V applications, consider alternatives such as the TPS5430 or externally compensated controllers.

What is the purpose of the NC pins (pins 2 and 3) on the TPS5420D SOIC package?

Pins 2 and 3 of the TPS5420D are designated as "No Connect" (NC) and are not bonded internally. They serve no electrical function and must remain unconnected on the PCB. Routing traces to or placing solder pads on these pins may introduce parasitic capacitance or noise coupling, potentially degrading switching performance or EMI behavior. TI's layout guidelines explicitly require leaving NC pins floating and unpopulated.

How does the voltage feed-forward feature improve performance in TPS5420D?

Voltage feed-forward in the TPS5420D dynamically adjusts the PWM ramp amplitude inversely with input voltage, maintaining constant power-stage gain across the 5.5V–36V input range. This eliminates the need for complex loop compensation adjustments and significantly improves line regulation and transient response-especially during fast input voltage steps. As a result, output voltage deviation during line transients is minimized without increasing output capacitance.

Is the TPS5420D pin-compatible with other devices in the TPS54xx family?

The TPS5420D shares the same 8-pin SOIC (D) package and pinout with the TPS5430DDAR, making them mechanically and electrically pin-compatible. However, it is not pin-compatible with TPS54202 or newer generations (e.g., TPS54201), which use different packages and pin assignments. Always verify pin functions and absolute maximum ratings before substitution-even within the same family-due to differences in internal protection thresholds and thermal characteristics.