Analog Devices Inc. LTC1682CMS8-5#TRPBF

Overview

LTC1682CMS8-5#TRPBF from Analog Devices (formerly Linear Technology) is a fixed 5V, low-noise charge pump doubler with integrated LDO regulator in an 8-pin MSOP package. It accepts 2.7V–4.4V input, delivers up to 50mA output current, achieves 64µV_RMS output noise (10Hz–100kHz), and operates at 550kHz switching frequency. It is designed for powering noise-sensitive VCOs in cellular phones and wireless PCMCIA cards.

For engineers reviewing the LTC1682CMS8-5#TRPBF datasheet, LTC1682CMS8-5#TRPBF pinout, LTC1682CMS8-5#TRPBF application, or LTC1682CMS8-5#TRPBF equivalent, key selection criteria include fixed 5V output accuracy (±2%), thermal shutdown protection, 1µA shutdown current, compatibility with ceramic capacitors only, and MSOP-8 footprint suitability for space-constrained RF power rails.

Technical Context

The LTC1682CMS8-5#TRPBF integrates a switched-capacitor voltage doubler and a low-dropout linear regulator in a single die. The doubler generates ~2×VIN at CPO, which feeds the LDO stage that filters ripple and regulates to a precise 5.0V output. Its internal 550kHz oscillator drives nonoverlapping clock phases to minimize charge injection and EMI.

Unlike adjustable versions, LTC1682CMS8-5#TRPBF uses an internal resistor divider to fix VOUT at 5.0V and repurposes Pin 3 as FILT (not FB), requiring a 1nF capacitor to ground for optimal reference filtering and noise reduction. Shutdown disconnects VIN from CPO and actively discharges VOUT via a 100Ω switch.

Key Specifications

Pinout & Package

Package: 8-pin MSOP (3mm × 3mm, 0.65mm pitch), thermally enhanced for surface-mount RF applications. GND (Pin 4) serves as primary thermal path; C+, C–, and FILT require minimal trace length and guard rings for noise immunity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-noise charge pump regulator applications.

Compared with LTC1682IMS8-5, the LTC1682CMS8-5#TRPBF offers identical functionality at lower cost for commercial-temperature designs; compared with LTC1522CS8-5, it trades higher quiescent current for integrated LDO filtering - eliminating external regulation and reducing BOM count by one component.

Availability

LTC1682CMS8-5#TRPBF is available at Aetrix Electronics and suitable for cellular phone VCO supplies, wireless PCMCIA card power rails, and portable medical instrument sensor biasing requiring stable component supply, full traceability, and long-term lifecycle support.

Supply support for LTC1682CMS8-5#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 full technical support, manufacturing continuity, and qualification for all legacy Linear parts including the LTC portfolio.

The LTC1682CMS8-5#TRPBF belongs to Linear's precision charge pump regulator family, engineered specifically for RF and analog subsystems demanding low-noise, inductorless voltage boosting in space- and power-constrained portable electronics.

FAQ

What is the output voltage tolerance of the LTC1682CMS8-5#TRPBF over temperature and load?

The LTC1682CMS8-5#TRPBF delivers a fixed 5.0V output with ±2% tolerance across the full commercial temperature range (0°C to 70°C) and for output currents from 1mA to 50mA. At 1mA load, the specification is tighter: 4.9V to 5.1V. This accuracy is achieved via laser-trimmed internal resistors and a 1.235V bandgap reference, ensuring stable VCO bias without external calibration.

Can the LTC1682CMS8-5#TRPBF operate from a 2.5V input supply?

No - the LTC1682CMS8-5#TRPBF requires a minimum input voltage of 2.7V per its absolute maximum ratings and electrical characteristics table. At 2.5V input, the internal charge pump cannot generate sufficient CPO voltage (>5.4V) to sustain regulation through the LDO's dropout margin, resulting in unregulated or unstable VOUT. For 2.5V input, consider the adjustable LTC1682CMS8 or LTC1522 variants.

Why does the LTC1682CMS8-5#TRPBF require a 1nF capacitor on the FILT pin?

The FILT pin on the LTC1682CMS8-5#TRPBF connects to the internal voltage reference node. A 1nF capacitor to ground provides high-frequency filtering of reference noise, directly improving output voltage accuracy and reducing VOUT RMS noise by ~6µV. Omitting this capacitor increases measured noise by up to 20% and degrades line/load regulation performance, especially under dynamic load conditions.

Is the LTC1682CMS8-5#TRPBF pin-compatible with the LTC1682CMS8-3.3#TRPBF?

Yes - both LTC1682CMS8-5#TRPBF and LTC1682CMS8-3.3#TRPBF use identical MSOP-8 packages and share identical pin functions: VOUT, SHDN, FILT, GND, C–, VIN, C+, and CPO. The only difference is internal resistor network configuration; no PCB layout change is needed when swapping between these fixed-output variants for design flexibility or voltage optimization.

How does the LTC1682CMS8-5#TRPBF handle short-circuit conditions on VOUT?

The LTC1682CMS8-5#TRPBF features internal current limiting and thermal shutdown. During a VOUT-to-ground short, output current is clamped to approximately 90mA (absolute maximum rating), preventing damage. If sustained, junction temperature rises above 150°C and triggers thermal shutdown; the device cycles on/off until fault removal. Unlike many regulators, it tolerates indefinite short-circuit without latch-up or degradation.