Analog Devices Inc. LTC3261EMSE#PBF

Overview

LTC3261EMSE#PBF from Analog Devices (formerly Linear Technology) is a high-voltage, low-quiescent-current inverting charge pump IC designed for bipolar supply generation in industrial and portable instrumentation. It operates from 4.5V to 32V input, delivers up to 100mA output current, regulates to –VIN in constant-frequency mode or –0.94·VIN in Burst Mode®, and features programmable 50kHz–500kHz switching via RT pin - used in portable medical equipment bias rails and precision analog front-ends.

For engineers reviewing the LTC3261EMSE#PBF datasheet, LTC3261EMSE#PBF pinout, LTC3261EMSE#PBF application, or LTC3261EMSE#PBF equivalent, key selection criteria include input voltage range (4.5V–32V), quiescent current in Burst Mode® (60µA), short-circuit/thermal protection, MSOP-12 exposed-pad thermal performance, and dual-mode operation (Burst vs. constant-frequency) for optimizing efficiency versus ripple in low-power instrumentation.

Technical Context

The LTC3261EMSE#PBF implements a four-switch flying-capacitor topology with internal logic-controlled phase sequencing. Its MODE pin selects between open-loop constant-frequency inversion (–VIN) and hysteretic Burst Mode® regulation (–0.94·VIN), while RT pin sets oscillator frequency from 50kHz to 500kHz using an external resistor to GND.

It integrates undervoltage lockout (3.4V/3.8V thresholds), shutdown current of 2µA, short-circuit current limiting (~160mA), and thermal shutdown at ~175°C with hysteresis (~165°C restart). The exposed pad (Pin 13) is GND and mandatory for thermal management and electrical integrity.

Key Specifications

Pinout & Package

The LTC3261EMSE#PBF is housed in a thermally enhanced 12-pin MSOP package (MSE12) with an exposed GND pad (Pin 13) that must be soldered to the PCB ground plane for thermal and electrical performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar inverting charge pump applications.

Compared with LTC3260EMSE#PBF, the LTC3261EMSE#PBF provides higher single-rail current (100mA vs. 50mA) and simpler BOM (no LDO capacitors), while LT3467EDD#TRPBF trades capacitor simplicity for superior efficiency and tighter output tolerance - making LTC3261EMSE#PBF the preferred choice for flexible, low-noise, inductorless negative rail generation in portable and precision instrumentation.

Availability

LTC3261EMSE#PBF is available at Aetrix Electronics and suitable for portable medical equipment, industrial instrumentation, and high-precision data acquisition systems requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for LTC3261EMSE#PBF 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

Analog Devices acquired Linear Technology in 2017 and maintains its high-performance analog IC portfolio. Linear Technology was renowned for innovative power management and signal conditioning solutions targeting demanding industrial and medical applications.

The LTC3261EMSE#PBF belongs to Linear's high-voltage charge pump family, engineered specifically for bipolar supply generation in portable, low-power, and precision analog systems - emphasizing quiescent current optimization, wide input range, and robust protection without external magnetics.

FAQ

What is the maximum input voltage the LTC3261EMSE#PBF can safely handle?

The LTC3261EMSE#PBF has an absolute maximum VIN rating of 36V, with recommended continuous operation up to 32V. Operation beyond 32V risks violating the specified electrical characteristics and may trigger undervoltage lockout (UVLO) release at 3.8V falling threshold. For reliable long-term use in 24V industrial systems, derating to ≤30V is advised to maintain margin against transients.

How does the MODE pin affect regulation accuracy and output ripple of the LTC3261EMSE#PBF?

When MODE = H, the LTC3261EMSE#PBF enters Burst Mode® and regulates VOUT to –0.94·VIN with ±1.5% typical accuracy and higher peak-to-peak ripple (e.g., 20mV at 5mA). When MODE = L, it operates in constant-frequency mode, delivering exactly –VIN with <0.5% line/load regulation but lower ripple (e.g., 5mV at 5mA). The choice directly trades regulation precision and noise for quiescent current.

Can the LTC3261EMSE#PBF drive a 100mA load continuously without thermal shutdown?

Yes - the LTC3261EMSE#PBF can sustain 100mA output at VIN = 12V (PD ≈ 1.2W) with proper thermal design: a 4-layer PCB, 2oz copper, ≥6 vias to a solid ground plane under the exposed pad, and θJA ≤ 40°C/W. At TA = 70°C, junction temperature reaches ~110°C - well below the 150°C continuous limit. Without adequate copper area, thermal shutdown at ~175°C will activate.

What is the purpose of the RT pin on the LTC3261EMSE#PBF, and how is it configured?

The RT pin on the LTC3261EMSE#PBF is a regulated 1.2V input that sets oscillator frequency via an external resistor to GND. A 200kΩ resistor yields ~200kHz; grounding RT fixes fOSC at 500kHz. This adjustment directly controls effective output impedance (lower ROL at higher fOSC) and ripple magnitude - critical for matching load dynamics and EMI requirements in the final design.

Does the LTC3261EMSE#PBF require external components for basic operation, and which ones are mandatory?

Yes - the LTC3261EMSE#PBF requires four mandatory external components: a 1µF+ ceramic flying capacitor (C+ to C–), ≥2µF ceramic input capacitor (VIN to GND), ≥2µF ceramic output capacitor (VOUT to GND), and an RT-to-GND resistor (or direct GND tie). No feedback resistors or compensation networks are needed - regulation is internal and mode-selectable via MODE/EN pins.