Texas Instruments LM27761DSGR

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 output capability, ultra-low 20 µV_RMS output noise (10 Hz–100 kHz), 30 mV LDO dropout at 100 mA, thermal/overcurrent protection, and WSON-8 (2.0 mm × 2.0 mm) package with exposed thermal pad.

Technical Context

The LM27761 integrates a 2 MHz charge-pump inverter followed by a negative LDO regulator - decoupling switching noise via post-regulation. Its feedback loop uses an external resistor divider on VFB referenced to a precise 1.22 V internal bandgap, enabling accurate output setting across temperature (±4% load regulation).

It operates in PFM mode under light loads to minimize quiescent current (370 µA typ.), transitions to constant-frequency 2 MHz operation at higher loads, and includes undervoltage lockout (2.4 V fall / 2.6 V rise), active output discharge in shutdown, and thermal shutdown at 150°C with hysteresis.

Key Specifications

Pinout & Package

LM27761 is housed in an 8-pin WSON (DSG) package 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 requires solder reflow per JEDEC J-STD-020.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX1759EUA+ and TPS60403DBVR, the LM27761 uniquely combines adjustable regulated output (−1.5 V to −5 V), 250 mA capability, ultra-low noise, and PFM efficiency - making it the only option suitable for high-fidelity analog biasing in compact portable systems.

Availability

LM27761 is available at Aetrix Electronics and suitable for operational amplifier power, cellular-phone power-amplifier biasing, and Hi-Fi headphone amplifier designs requiring stable component supply, consistent parametric performance, and long-term production continuity.

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 leader specializing in analog, embedded processing, and connectivity technologies, with decades of expertise in power management ICs.

The LM27761 belongs to TI's regulated charge-pump inverter product line, designed specifically for low-noise, space-constrained portable electronics requiring clean negative bias rails without inductors.

FAQ

What is the minimum input voltage required for stable operation of the LM27761?

The LM27761 has an undervoltage lockout threshold of 2.4 V (falling) and 2.6 V (rising). Stable operation requires VIN ≥ 2.7 V per recommended conditions - below this, regulation degrades and the device may enter shutdown. At VIN = 2.7 V, the LM27761 can still deliver −1.5 V output with full 250 mA capability, provided thermal limits are observed.

How do I set the output voltage of the LM27761 to −3.3 V?

To set LM27761 output to −3.3 V, use the formula VOUT = −1.22 V × (R1 + R2)/R2. With VREF = 1.22 V, solving yields R1/R2 ≈ 1.71. Select R2 = 500 kΩ (minimum recommended), then R1 = 855 kΩ (standard 1% value). Connect R1 between VOUT and VFB, R2 between VFB and GND - ensuring VFB remains at 1.22 V.

Does the LM27761 require an external LDO for low-noise performance?

No - the LM27761 integrates a negative LDO regulator after the charge-pump stage, eliminating the need for external LDOs. Its 20 µV_RMS output noise (10 Hz–100 kHz) and 35 dB PSRR at 2 MHz are achieved internally, confirmed in electrical characteristics tables and typical curves of the official datasheet.

Can the LM27761 drive a 250 mA load continuously without thermal shutdown?

Yes - the LM27761 supports 250 mA continuous output under proper thermal conditions. With R_θJA = 67.7 °C/W and TJ_MAX = 125°C, maximum allowable ambient temperature at 250 mA and VIN = 5.5 V is ~65°C (calculated via PD = VIN×I_Q − VOUT×I_OUT). Use the exposed thermal pad and adequate copper area to maintain safe junction temperature.

What capacitor types are recommended for the LM27761 flying capacitor C1?

Texas Instruments explicitly recommends non-polarized multilayer ceramic capacitors (MLCCs) for C1 - specifically X7R or X5R dielectrics rated ≥10 V. Polarized capacitors (tantalum, aluminum electrolytic, OS-CON) are prohibited due to reverse-bias risk during charge-pump switching cycles. A 1 µF, 10 V, 0603 X7R MLCC is the standard recommendation per typical application diagrams.