Analog Devices Inc. LTC1261CS8-4.5#TRPBF

Overview

LTC1261CS8-4.5#TRPBF from Analog Devices (formerly Linear Technology) is a fixed-output switched-capacitor voltage inverter IC that generates a regulated –4.5V negative supply from a single 3V–8V positive input. It delivers up to 12mA output current with ±5% regulation, features an open-drain REG pin for power-valid indication, and operates with only one external 0.1µF flying capacitor in 8-lead SOIC package. It is used in battery-powered systems requiring compact, low-noise dual-rail supplies.

For engineers reviewing the LTC1261CS8-4.5#TRPBF datasheet, LTC1261CS8-4.5#TRPBF pinout, LTC1261CS8-4.5#TRPBF application, or LTC1261CS8-4.5#TRPBF equivalent, key selection criteria include fixed –4.5V output, 550kHz internal oscillator, shutdown mode (5µA quiescent), 5mV typical output ripple at 5mA, and SO-8 thermal performance (θ_JA = 150°C/W).

Technical Context

The LTC1261CS8-4.5#TRPBF implements a doubler-mode charge pump architecture with internal 1.24V reference and precision feedback comparator (COMP1) to regulate output voltage by dynamically adjusting duty cycle. Its fixed –4.5V output is achieved via on-die resistor string connected to ADJ/COMP pin - no external resistors required.

It integrates an open-drain REG output that sinks up to 8mA when V_OUT is within ±5% of –4.5V, and a shutdown control (SHDN) that disables the oscillator and reduces supply current to 5µA. The device requires no external timing components and uses only one 0.1µF ceramic flying capacitor between C1+ and C1–.

Key Specifications

Pinout & Package

Package: 8-lead plastic SOIC (SO-8), 0°C to 70°C operating range, θ_JA = 150°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX680ESA+ and ICL7660SIPAZ, the LTC1261CS8-4.5#TRPBF offers tighter output regulation (±5% vs ±10%), lower ripple (5mV vs 100mV), integrated REG signaling, and higher efficiency at 550kHz - making it optimal for precision, space-constrained, and safety-monitored applications.

Availability

LTC1261CS8-4.5#TRPBF is available at Aetrix Electronics and suitable for portable instrumentation power, GaAs FET bias generation, and battery-powered sensor nodes requiring stable component supply across production lifecycles.

Supply support for LTC1261CS8-4.5#TRPBF 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 legacy precision analog and power management product lines with full datasheet, reliability, and support continuity.

The LTC1261 series was designed specifically for compact, low-noise regulated negative voltage generation in space- and power-constrained systems - targeting portable test equipment, RF bias, and industrial signal conditioning.

FAQ

What output voltage does the LTC1261CS8-4.5#TRPBF deliver?

The LTC1261CS8-4.5#TRPBF delivers a fixed –4.5V regulated output voltage. This value is set by an internal resistor string connected to the COMP pin, eliminating the need for external feedback resistors. The device maintains this output within ±5% over load (0–12mA) and temperature (0°C to 70°C), as confirmed in the Electrical Characteristics table of the official datasheet.

How many external capacitors does the LTC1261CS8-4.5#TRPBF require?

The LTC1261CS8-4.5#TRPBF requires three external capacitors: one 0.1µF ceramic flying capacitor between C1+ and C1–, one ≥3.3µF low-ESR output capacitor from OUT to GND, and one ≥0.1µF ceramic bypass capacitor from VCC to GND. An optional 100pF compensation capacitor from COMP to GND further reduces output ripple under dynamic loads.

Does the LTC1261CS8-4.5#TRPBF include a power-good indicator?

Yes, the LTC1261CS8-4.5#TRPBF includes an open-drain REG pin that pulls low when the output voltage is within ±5% of –4.5V. This pin sinks up to 8mA with a 5V pull-up and can be interfaced directly with microcontroller GPIOs or supervisor ICs to implement power-valid sequencing - a feature not present in basic charge pump ICs like the ICL7660.

What is the shutdown current of the LTC1261CS8-4.5#TRPBF?

The shutdown current of the LTC1261CS8-4.5#TRPBF is 5µA typical, as specified in the Electrical Characteristics table. When the SHDN pin is pulled high, the internal oscillator stops, the charge pump halts, and the output collapses to 0V. This ultra-low shutdown current makes the LTC1261CS8-4.5#TRPBF suitable for battery-powered applications requiring extended standby time.

Can the LTC1261CS8-4.5#TRPBF operate from a 3.3V input supply?

Yes, the LTC1261CS8-4.5#TRPBF operates from a 3V to 8V input supply, fully supporting 3.3V rails. At 3.3V input, it delivers –4.5V output with guaranteed regulation up to 6mA load (per Electrical Characteristics, Note 6), making it viable for low-voltage portable systems where higher input voltages are unavailable.