Texas Instruments LM3279TLX/NOPB

Overview

LM3279TLX/NOPB from Texas Instruments is a buck-boost DC/DC converter optimized for RF power amplifier (PA) supply in 3G/4G mobile devices, supporting input voltage range 2.7 V to 5.5 V, digitally programmable output 0.4 V to 4.2 V via MIPI RFFE interface, and delivering up to 1 A at V_OUT = 3.6 V when V_BATT ≥ 3.2 V.

For engineers reviewing the LM3279TLX/NOPB datasheet, LM3279TLX/NOPB pinout, LM3279TLX/NOPB application, or LM3279TLX/NOPB equivalent, key selection considerations include its 2.4-MHz switching frequency, seamless buck-boost mode transition, fast 20-µs V_OUT slew (0.8 V → 4 V), internal compensation, and dual control modes (RFFE digital or analog VCON).

Technical Context

The LM3279TLX/NOPB integrates a synchronous four-switch buck-boost topology with integrated gate drivers and internal loop compensation for both buck and boost operation. It supports three operating modes-PWM (2.4 MHz typ.), PFM (63 kHz typ. at light load), and standby-with automatic, seamless transitions between buck, boost, and buck-boost regions based on input-output voltage relationship.

Control is implemented via either MIPI RFFE (SCLK/SDATA/VIO) or analog voltage on VCON (0.167 V–1.4 V, gain = 3×), enabling dynamic PA voltage scaling. The device includes input overcurrent protection (1.7 A typ.), output overvoltage clamp, thermal shutdown (150°C), and two GPIOs (GPO0/GPO1) for RF front-end configuration.

Key Specifications

Pinout & Package

LM3279TLX/NOPB uses a 16-bump DSBGA package (2.529 mm × 2.146 mm, 0.4-mm pitch), optimized for ultra-compact mobile RF power management. Bump assignment follows TI's standard top-view (bumps down) layout.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar buck-boost RF PA supply applications.

Compared with LM3279TLX/NOPB, TPS63020DSJR lacks digital interface and fast slew capability, limiting adaptability in envelope-tracking architectures; MAX20420ATPA+T provides broader voltage range and integrated LDO but requires protocol translation and does not match RFFE timing behavior or register-level PA control semantics.

Availability

LM3279TLX/NOPB is available at Aetrix Electronics and suitable for 3G/4G smartphones, cellular tablets, and battery-powered RF modules requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for LM3279TLX/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 ICs, with decades of experience in mobile power solutions and RF infrastructure.

The LM3279TLX/NOPB belongs to TI's RF Power Management product line, designed specifically to address dynamic voltage scaling, high efficiency, and ultra-small footprint requirements of cellular PA subsystems in portable wireless devices.

FAQ

What is the primary function of the LM3279TLX/NOPB in a cellular RF system?

The LM3279TLX/NOPB serves as a dynamically controllable buck-boost DC/DC converter that supplies precisely regulated, variable voltage to RF power amplifiers in 3G/4G handsets and modules. Its core function is to maintain PA efficiency across varying battery voltages and transmit power levels by adjusting V_OUT from 0.4 V to 4.2 V - either via MIPI RFFE commands or analog VCON voltage - while delivering up to 1 A with minimal size and high efficiency. This ensures optimal linearity and battery life in real-world cellular operation.

Does the LM3279TLX/NOPB require external feedback resistors to set output voltage?

No, the LM3279TLX/NOPB does not require external feedback resistors. It uses an internal DAC-based feedback network where output voltage is set either by writing to the VSET register (00h) via the MIPI RFFE interface or by applying an analog voltage (0.167 V–1.4 V) to the VCON pin, which is internally amplified by a fixed gain of 3× to produce V_OUT. This eliminates resistor tolerance errors, saves PCB area, and enables true dynamic reconfiguration without hardware changes.

How does the LM3279TLX/NOPB handle transitions between buck and boost operating modes?

The LM3279TLX/NOPB implements seamless buck-boost mode transition through an internal zero-crossing detector and state-machine-controlled gate drive logic. When input voltage approaches output voltage, the controller automatically adjusts duty cycle and switch activation sequence without output disturbance or control-loop instability. This behavior is verified across temperature and load, ensuring uninterrupted PA operation during battery discharge - a critical requirement for maintaining RF signal integrity in cellular standards.

What are the key timing specifications for dynamic V_OUT adjustment in the LM3279TLX/NOPB?

The LM3279TLX/NOPB achieves 0.8 V to 4 V V_OUT transition in ≤20 µs with a 5-Ω load at V_BATT = 3.8 V, meeting stringent LTE/WCDMA envelope tracking timing requirements. RFFE register writes complete in <25 µs (including SCLK setup/hold), and V_OUT settles to 90% of final value within 50 µs after VIO assertion. These values are measured under typical application conditions (1.5-µH inductor, 10-µF output cap) and are guaranteed across −30°C to 85°C ambient.

Can the LM3279TLX/NOPB operate without the MIPI RFFE interface?

Yes, the LM3279TLX/NOPB supports full analog control mode using the EN and VCON pins - with VIO tied to GND - enabling operation in systems lacking RFFE-capable baseband or RFIC. In this mode, V_OUT is set by VCON (0.167 V–1.4 V → 0.5 V–4.2 V), EN enables/disables regulation (>1.2 V = active), and GPO0/GPO1 remain functional under register control via default values. All electrical specs, including efficiency and transient response, remain valid in analog mode.