Texas Instruments LM27761DSGT

Overview

LM27761 from Texas Instruments is a low-noise, regulated switched-capacitor voltage inverter IC that inverts and regulates input voltages from 2.7 V to 5.5 V to produce an adjustable negative output between −1.5 V and −5 V. It delivers up to 250 mA output current with ±4% regulation at peak load, 2 MHz fixed-frequency operation, and 35 dB PSRR at 2 MHz - enabling high-fidelity biasing for op-amps and data converters in portable instrumentation.

For engineers reviewing the LM27761 datasheet, LM27761 pinout, LM27761 application, or LM27761 equivalent, key selection considerations include its regulated negative LDO output stage, 30 mV dropout at 100 mA, 20 µV_RMS output noise (10 Hz–100 kHz), thermal shutdown at 150°C, and compatibility with standard 2.0 mm × 2.0 mm WSON-8 packages with exposed thermal pad.

Technical Context

The LM27761 integrates a 2 MHz charge-pump inverter followed by a negative LDO regulator - not a simple inverter but a two-stage architecture where the LDO suppresses switching ripple and improves PSRR. Its feedback loop uses an internal 1.22 V reference and external resistor divider (R1/R2) to set VOUT precisely across the −1.5 V to −5 V range.

Functional modes include active operation (370 µA quiescent current), shutdown (7 µA), and PFM pulse-skipping under light loads. Protection features are integrated: undervoltage lockout (2.4 V fall / 2.6 V rise), input current limiting (~500 mA), and thermal shutdown with hysteresis (150°C trip / 130°C release).

Key Specifications

Pinout & Package

LM27761 is housed in an 8-pin WSON package (DSG) measuring 2.00 mm × 2.00 mm with an exposed thermal pad on the bottom for enhanced thermal performance. The package is RoHS-compliant and moisture-sensitive level 2 (MSL-2).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar regulated negative voltage inverter applications.

Compared with MAX1682EUT+T and TPS60403DBVR, the LM27761 uniquely combines 250 mA output, integrated thermal/UVLO protection, 2 MHz operation for compact capacitors, and 35 dB PSRR - making it the only option capable of directly powering high-fidelity audio and precision data-converter rails without supplemental regulation.

Availability

LM27761 is available at Aetrix Electronics and suitable for operational amplifier power, Hi-Fi headphone amplifiers, and cellular-phone power-amplifier biasing requiring stable component supply across automotive-grade temperature ranges (−40°C to +85°C) and long-lifecycle production programs.

Supply support for LM27761 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.

The LM27761 belongs to TI's precision power management portfolio, designed specifically for low-noise, high-PSRR negative rail generation in battery-powered analog signal chains - addressing noise-critical applications where traditional inverters fail.

FAQ

What is the maximum output current capability of the LM27761?

The LM27761 delivers up to 250 mA of continuous output current at the VOUT pin under recommended operating conditions (TA = −40°C to +85°C, VIN = 2.7 V to 5.5 V). This rating assumes proper thermal management via the exposed thermal pad and use of specified low-ESR ceramic capacitors. At 250 mA, regulation remains within ±4%, and dropout voltage stays below 30 mV for VOUT = −5 V.

How is the output voltage of the LM27761 set and adjusted?

The LM27761 output voltage is set using an external resistor divider connected between VOUT, VFB, and GND. The formula is VOUT = −1.22 V × (R1 + R2)/R2, where R2 must be ≥50 kΩ. For example, R1 = 237 kΩ and R2 = 500 kΩ yields −1.8 V. The internal 1.22 V reference ensures accuracy across temperature, and the feedback pin (VFB) must never be left floating.

Does the LM27761 require special capacitors, and why?

Yes - the LM27761 requires four low-ESR X7R or X5R multilayer ceramic capacitors (MLCCs): 1 µF flying (C1), 4.7 µF input (C2), 4.7 µF charge-pump output (C3), and 2.2 µF LDO output (C4). Polarized capacitors (tantalum, aluminum) are prohibited for C1 due to reverse-bias risk. Y5V/Z5U dielectrics are excluded because their capacitance can drop >80% under DC bias, causing regulation failure and excessive ripple.

What protection features does the LM27761 include?

The LM27761 integrates undervoltage lockout (2.4 V falling / 2.6 V rising), input current limiting (~500 mA), thermal shutdown (150°C trip with 20°C hysteresis), and active output discharge in shutdown (1.85 mA sink). These functions operate autonomously without external components - protecting both the IC and downstream circuitry during fault conditions such as shorted outputs or overheating.

Can the LM27761 be used in battery-powered portable devices?

Yes - the LM27761 is optimized for portable applications: it draws only 370 µA quiescent current during operation and just 7 µA in shutdown mode. Its 2.7 V to 5.5 V input range matches single-cell Li-ion (3.0–4.2 V) and USB-powered systems. Combined with 250 mA output and low noise, it powers op-amps, DACs, and headphone amps in handheld instrumentation and wireless audio devices without compromising runtime.