Analog Devices Inc. LTC1261LIS8-4.5#TRPBF

Overview

LTC1261LIS8-4.5#TRPBF from Analog Devices (acquired Linear Technology) is a fixed-output switched-capacitor voltage inverter IC that generates –4.5V from a single 4.75V–5.25V positive supply, delivers up to 20mA output current, maintains ±4.5% output regulation, and features an open-drain REG pin indicating regulation status - used in GaAs FET bias generation and battery-powered negative rail applications.

For engineers reviewing the LTC1261LIS8-4.5#TRPBF datasheet, LTC1261LIS8-4.5#TRPBF pinout, LTC1261LIS8-4.5#TRPBF application, or LTC1261LIS8-4.5#TRPBF equivalent, key selection criteria include guaranteed –4.5V output at 5mA under 4.75–5.25V input, 650kHz internal oscillator frequency, 5µA shutdown quiescent current, MSOP-8 package compatibility, and REG pin logic behavior referenced to VOUT.

Technical Context

The LTC1261LIS8-4.5#TRPBF implements a charge-pump topology with internal 650kHz oscillator driving complementary MOSFET switches to invert and regulate voltage. Its feedback loop compares a divided replica of VOUT against a 1.23V internal reference via the ADJ/COMP pin, enabling cycle-by-cycle duty-cycle control for regulation.

Regulation accuracy relies on internal resistor divider connected to ADJ (COMP), while the REG pin uses a separate 1.17V comparator threshold to indicate ±5% output tolerance. Output short-circuit protection is inherent, with indefinite short-circuit duration capability and 100–220mA short-circuit current at VCC = 5.25V.

Key Specifications

Pinout & Package

Package: 8-lead plastic SO (S8), 0.150-inch narrow body, –40°C to +85°C industrial temperature range, θJA = 135°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar switched-capacitor voltage inverter applications.

Compared with MAX680ESA+ and LTC1044CS8#PBF, the LTC1261LIS8-4.5#TRPBF uniquely delivers guaranteed –4.5V with ±4.5% regulation, integrated REG signaling, and 650kHz operation enabling smaller external components - making it optimal for GaAs bias and portable instrumentation where voltage precision and compactness are critical.

Availability

LTC1261LIS8-4.5#TRPBF is available at Aetrix Electronics and suitable for GaAs FET bias generation, battery-powered negative rail systems, and single-supply signal conditioning requiring stable component supply and industrial temperature support.

Supply support for LTC1261LIS8-4.5#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, Inc. (ADI) is a global semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies.

The LTC1261L series was designed by Linear Technology (now part of ADI) specifically for compact, low-noise regulated negative voltage generation in RF, portable, and industrial systems using switched-capacitor architecture.

FAQ

What is the guaranteed output voltage tolerance for LTC1261LIS8-4.5#TRPBF?

The LTC1261LIS8-4.5#TRPBF guarantees ±4.5% output regulation over its full operating conditions: 4.75–5.25V input, 0–10mA load, and –40°C to +85°C ambient. At 5mA load and 5V input, the output is specified between –4.657V and –4.343V. This tolerance reflects total error including line, load, and temperature effects - not just initial accuracy.

Does LTC1261LIS8-4.5#TRPBF require external resistors to set the output voltage?

No, the LTC1261LIS8-4.5#TRPBF does not require external resistors. It is a fixed-output variant with internal resistor divider connected to the ADJ/COMP pin, configured to deliver precisely –4.5V. External resistors are only needed for adjustable versions like the base LTC1261L; adding them to LTC1261LIS8-4.5#TRPBF would disrupt regulation.

What is the function of the REG pin on LTC1261LIS8-4.5#TRPBF?

The REG pin on LTC1261LIS8-4.5#TRPBF is an open-drain output that pulls low when |VOUT| is within 5% of the nominal –4.5V setpoint (i.e., VOUT ≥ –4.275V). It sinks up to 5mA at 5V VCC and requires an external pull-up. It serves as a power-valid indicator for system sequencing or fault monitoring - not a regulator enable signal.

Can LTC1261LIS8-4.5#TRPBF operate below 4.75V supply voltage?

The LTC1261LIS8-4.5#TRPBF may function below 4.75V, but output regulation is not guaranteed per datasheet specifications. The minimum 4.75V is defined to ensure ±4.5% accuracy across temperature and load. Operation at 4.5V may yield degraded regulation (e.g., –4.3V), higher ripple, or failure to start - verify experimentally if used outside spec limits.

What package type and temperature grade does LTC1261LIS8-4.5#TRPBF use?

The LTC1261LIS8-4.5#TRPBF uses an 8-lead plastic SO (S8) package with 0.150-inch narrow body and is rated for the industrial temperature range of –40°C to +85°C. The "I" in "LIS8" denotes industrial grade, and "#TRPBF" indicates lead-free, tape-and-reel packaging - confirmed in Linear Technology's order information table.