Texas Instruments LM3242TMX/NOPB

Overview

LM3242TMX/NOPB from Texas Instruments is a 6-MHz, 750-mA synchronous step-down DC-DC converter optimized for RF power amplifier (PA) biasing in single-cell Li-ion systems; features auto-bypass mode with <50 mV dropout, 0.4 V to 3.6 V analog-programmable output via VCON pin, and integrated PFET/NFET/BPFET switches in a 9-bump DSBGA package.

For engineers reviewing the LM3242TMX/NOPB datasheet, LM3242TMX/NOPB pinout, LM3242TMX/NOPB application, or LM3242TMX/NOPB equivalent, key selection considerations include dynamic VCON-based PA voltage scaling, ECO/PWM/BP mode transition thresholds, thermal shutdown at 150°C, 95% peak efficiency at 500 mA, and DSBGA package assembly requirements for high-density RF layouts.

Technical Context

The LM3242TMX/NOPB implements a voltage-mode buck architecture with input voltage feedforward for stable regulation across 2.7 V–5.5 V input range. It integrates three power switches: a 260 mΩ PFET, 200 mΩ NFET, and 110 mΩ BPFET - enabling seamless transitions between PWM (6 MHz fixed), ECO (reduced-frequency light-load), and bypass modes without external components.

Operation is governed by five functional states: Shutdown (0.1 µA IQ), Sleep (<80 mV VCON), PWM (>130 mV VCON & >100 mA load), ECO (<50 mA load), and Bypass (VCON > VIN/2.5 or BPEN = high). Auto-bypass activation uses hysteresis with VBP,NEG = 200 mV and VBP,POS = 250 mV, ensuring robust low-dropout operation during battery sag.

Key Specifications

Pinout & Package

LM3242TMX/NOPB is housed in a lead-free 9-bump DSBGA (YFQ) package measuring 1.51 mm × 1.385 mm with 0.4-mm bump pitch. The package requires controlled-environment reflow and opaque-board placement to avoid IR-sensitive edge effects.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RF PA DC-DC converter applications.

Compared with TPS62260DRVR and MAX8640YETA+, the LM3242TMX/NOPB uniquely delivers true analog-dynamic PA biasing with sub-50-mV bypass dropout and 6-MHz switching in the smallest DSBGA footprint - making it the only option for space-constrained, battery-sag-resilient RF power management in modern handsets.

Availability

LM3242TMX/NOPB is available at Aetrix Electronics and suitable for battery-powered 3G/4G RF PAs, handheld radios, RF PC cards, and portable IoT transceivers requiring stable component supply across extended production lifecycles.

Supply support for LM3242TMX/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 expertise in high-efficiency DC-DC conversion and RF system solutions.

The LM3242TMX/NOPB belongs to TI's RF Power Management product line, designed specifically to address dynamic voltage scaling, low-noise operation, and ultra-compact integration needs of cellular and wireless infrastructure transmitters.

FAQ

What is the function of the VCON pin on the LM3242TMX/NOPB?

The VCON pin on the LM3242TMX/NOPB is an analog input that directly sets the output voltage according to VOUT = 2.5 × VCON, covering 0.4 V to 3.6 V across a 0.16 V–1.44 V input range. It enables real-time PA efficiency optimization without digital interface overhead, and can force bypass mode when VCON exceeds VIN/2.5. This pin must be driven with low-impedance source due to ±1 µA leakage spec.

How does the LM3242TMX/NOPB enter and exit auto-bypass mode?

The LM3242TMX/NOPB enters auto-bypass mode when VIN − (2.5 × VCON) falls below 200 mV (VBP,NEG) for longer than 10 µs, turning on the internal BPFET and disabling PWM switching. It exits bypass when VIN − (2.5 × VCON) exceeds 250 mV (VBP,POS) for longer than 0.1 µs, resuming PWM regulation. This hysteresis prevents oscillation during marginal battery conditions.

What is the maximum continuous output current capability of the LM3242TMX/NOPB in different operating modes?

In PWM mode, the LM3242TMX/NOPB delivers up to 750 mA continuously (per datasheet recommended conditions). In Bypass mode - either forced (BPEN = high) or auto - it supports up to 1000 mA due to lower RDS(ON) of the parallel BPFET + PWM path (75 mΩ total). Current capability remains limited by thermal design; junction temperature must stay ≤125°C under sustained load.

Can the LM3242TMX/NOPB be used with a 0.47-µH inductor instead of the recommended 0.5-µH value?

Yes - the LM3242TMX/NOPB supports inductors from 0.47 µH to 0.68 µH per TI's layout guidelines. A 0.47-µH part maintains stability and meets ripple specs if rated for ≥1.5 A saturation current and ≤50 mΩ DCR. However, peak inductor current increases slightly, so thermal validation at max load and temperature is required before final design sign-off.

What are the critical PCB layout requirements for the LM3242TMX/NOPB DSBGA package?

LM3242TMX/NOPB DSBGA layout requires strict separation of PGND and SGND planes, short low-inductance paths for VIN–SW–PGND loop, and dedicated thermal vias under the exposed die pad (if applicable). Bump pitch is 0.4 mm, demanding Class II IPC-7351B footprint, solder mask defined pads, and stencil aperture reduction to prevent bridging. Avoid placing components or traces within 0.3 mm of package edges due to IR sensitivity.