Texas Instruments LM4734TABD

Overview

LM4734TABD from Texas Instruments is a 3-channel audio power amplifier IC delivering 20W per channel into 4Ω or 8Ω loads at ≤10% THD+N (20Hz–20kHz), featuring independent mute and standby control per channel, wide ±10V to ±30V supply range, and integrated thermal shutdown at 150°C. It targets multi-channel consumer audio systems requiring high-fidelity output with low external component count.

For engineers reviewing the LM4734TABD datasheet, LM4734TABD pinout, LM4734TABD application, or LM4734TABD equivalent, key selection criteria include per-channel mute/standby logic interface compatibility, TO-220-27 thermal performance (θJC = 1.0°C/W), 110dB typical mute attenuation, and bridged/parallel configuration support for HTIB and high-end TV designs.

Technical Context

The LM4734TABD integrates three fully independent Class-AB amplifier channels on a single die, each with dedicated MUTE and STANDBY input pins enabling selective channel disabling without affecting others. Its under-voltage lockout prevents click/pop during power-up/down, while over-voltage protection limits output current via transistor-based clamping-not internal diodes.

Thermal protection operates as a Schmitt-triggered shutdown: activation at 150°C and recovery at ~145°C to minimize cycling stress. The device supports bridge-tied load (BTL) and parallel configurations-BTL doubles voltage swing (theoretically ×4 power), while parallel operation increases current drive for ≤4Ω loads using external 0.1Ω balancing resistors.

Key Specifications

Pinout & Package

LM4734TABD uses a 27-lead TO-220 package (NDM0027A) with electrically isolated backplate when mica washer is used; metal tab connects to V− when only thermal compound is applied. Thermal resistance θJC = 1.0°C/W enables high-power dissipation with minimal junction-to-case delta.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3-channel audio amplifier applications.

Compared with TAS5630PHDR and TPA3116D2PWPR, LM4734TABD offers native 3-channel analog amplification with per-channel logic control, lower THD+N at mid-power levels, and simpler thermal management-making it optimal for analog-centric, high-fidelity consumer audio where signal purity and design simplicity are prioritized over peak efficiency.

Availability

LM4734TABD is available at Aetrix Electronics and suitable for home theater in a box (HTIB), high-end TV audio subsystems, and compact stereo amplifiers requiring stable component supply, long-lifecycle support, and consistent parametric performance across production batches.

Supply support for LM4734TABD 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 and embedded processing technologies, with decades of expertise in high-performance audio IC design and manufacturing.

The LM4734 product line was engineered specifically for cost-sensitive, high-fidelity 3-channel consumer audio applications-including HTIB, premium TVs, and compact stereo-balancing output power, thermal robustness, and minimal external component count.

FAQ

What is the maximum safe operating temperature for LM4734TABD?

The LM4734TABD has a maximum junction temperature (TJMAX) of 150°C, at which its thermal shutdown circuit activates. Recovery occurs at approximately 145°C. To ensure reliable operation, the heatsink must maintain junction temperature below 150°C under worst-case load conditions-verified using θJA = 30°C/W and ambient temperature derating per TI's DETERMINING THE CORRECT HEAT SINK guidelines. LM4734TABD thermal performance is validated in the SNAS239B datasheet.

Does LM4734TABD support single-supply operation?

Yes, LM4734TABD supports single-supply operation using external biasing components (RA, CA, RE, RINP, RBI) as shown in Figure 5 of the SNAS239B datasheet. This configuration establishes a virtual ground at half-supply, enabling AC-coupled input and output. However, split-supply (±V) operation is the default and recommended mode for optimal PSRR, THD+N, and output swing. LM4734TABD single-supply implementation requires careful attention to DC bias stability and ripple rejection.

How does the mute function work on LM4734TABD?

LM4734TABD implements active-high mute: applying ≥2.0V to any MUTE1–MUTE3 pin attenuates that channel's output by 110dB typical. Mute transitions are smooth (fade-in/out) to prevent clicks. Each channel's mute is fully independent-e.g., MUTE1 can silence the left channel while MUTE2/MUTE3 remain low for active right/center output. LM4734TABD mute behavior is characterized in Figure 25 and detailed in the APPLICATION INFORMATION section of SNAS239B.

Can LM4734TABD be used in bridged (BTL) mode?

Yes, LM4734TABD supports bridged-tied load (BTL) configuration using two of its three channels-e.g., Channel 1 drives one side of the load while Channel 3 (inverted signal) drives the other. This doubles output voltage swing, theoretically quadrupling power into the same load. Figure 3 in SNAS239B shows the BTL schematic. LM4734TABD BTL operation requires matched gain-setting resistors and careful thermal management due to doubled power dissipation per bridged channel.

What is the purpose of the under-voltage lockout (UVLO) in LM4734TABD?

The UVLO circuit in LM4734TABD prevents amplifier turn-on until both V+ and V− reach safe thresholds (V− ≥ −9.5V relative to GND, and |V+| + |V−| > 14V). This eliminates DC output spikes during power-up and forces outputs to ground before supplies decay during power-down-ensuring click- and pop-free operation. UVLO behavior is integral to LM4734TABD's robustness in consumer audio systems with unregulated supplies.