Analog Devices Inc. LTC1682IS8#TRPBF

Overview

LTC1682IS8#TRPBF from Analog Devices (formerly Linear Technology) is a fixed-output 3.3V low-noise charge pump doubler with integrated LDO regulator, designed for powering noise-sensitive RF circuitry such as VCOs in cellular phones and wireless PCMCIA cards. It operates from 2.0V to 4.4V input, delivers up to 50mA output current, achieves 58µV_RMS output noise (10Hz–100kHz), and features 550kHz switching frequency with Burst Mode efficiency optimization.

For engineers reviewing the LTC1682IS8#TRPBF datasheet, LTC1682IS8#TRPBF pinout, LTC1682IS8#TRPBF application, or LTC1682IS8#TRPBF equivalent, key selection criteria include its guaranteed –40°C to 85°C industrial temperature range, 3.3V ±3% regulated output tolerance at 1mA load, 1µA shutdown current, internal thermal/short-circuit protection, and compatibility with ceramic capacitors only-no inductors required.

Technical Context

The LTC1682IS8#TRPBF integrates a switched-capacitor voltage doubler and a low-dropout linear regulator in a single 8-pin SO package. Its charge pump generates ~2×VIN at CPO, which feeds an LDO stage that filters ripple and regulates to a precise 3.3V output. The device uses a trimmed 550kHz oscillator and slew-controlled switches to minimize EMI while maintaining low output noise.

Operation includes power-on reset, automatic LDO enable/disable based on CPO voltage thresholds (1.75×VIN enable, 1.45×VIN disable), and Burst Mode activation below 100µA load to reduce quiescent current. Internal protection includes thermal shutdown at 150°C and current limiting, with indefinite short-circuit tolerance on VOUT.

Key Specifications

Pinout & Package

Package: 8-lead plastic SO (narrow, 0.150-inch width), RoHS-compliant, tape-and-reel (TRPBF suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC1682IMS8-3.3, the LTC1682IS8#TRPBF offers better thermal performance in high-ambient environments due to lower θ_JA, while LT1761CS8-3.3 provides lower noise but lacks input voltage boosting - making LTC1682IS8#TRPBF uniquely suited for 2.0V–4.4V battery-powered RF biasing.

Availability

LTC1682IS8#TRPBF is available at Aetrix Electronics and suitable for cellular phone VCO supplies, wireless PCMCIA card power, 2-way pager RF front-ends, portable medical instrument sensor bias, and remote transmitter applications requiring stable component supply across industrial temperature ranges.

Supply support for LTC1682IS8#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 product support, manufacturing, and documentation for legacy Linear parts including the LTC1682 series.

The LTC1682IS8#TRPBF belongs to Linear's precision low-noise power management family, engineered specifically for RF and analog signal chain applications where supply noise directly impacts system-level phase noise, SNR, and dynamic range.

FAQ

What is the guaranteed operating temperature range for the LTC1682IS8#TRPBF?

The LTC1682IS8#TRPBF is specified for industrial temperature operation from –40°C to +85°C, with all electrical characteristics guaranteed across this full range. This distinguishes it from the commercial-grade LTC1682CS8-3.3 (0°C to 70°C) and makes it suitable for automotive infotainment modules, industrial radios, and outdoor wireless equipment where ambient extremes are expected. The part uses internal thermal shutdown at 150°C to protect against overload conditions.

Can the LTC1682IS8#TRPBF generate a 5V output?

No, the LTC1682IS8#TRPBF is a fixed 3.3V version and cannot produce 5V output. It is part of the LTC1682-3.3 variant family, with internal resistor divider setting VOUT = 3.3V ±3%. For 5V output, the correct part is LTC1682IS8-5, which shares identical package, pinout, and thermal specs but delivers 4.9V–5.1V regulated output. Attempting to force 5V from LTC1682IS8#TRPBF will result in under-regulation and excessive dropout.

What capacitor values are mandatory for stable operation of the LTC1682IS8#TRPBF?

The LTC1682IS8#TRPBF requires three mandatory capacitors: a 0.22µF ceramic flying capacitor between C+ and C– pins; a 1nF ceramic capacitor from FILT to GND (critical for achieving 58µV_RMS noise); and ≥2µF low-ESR ceramic capacitor on VOUT. Input VIN also requires ≥2µF ceramic bypass. All capacitors must be X5R/X7R dielectric; tantalum or electrolytic types are not recommended due to ESR and reliability concerns in this high-frequency charge pump topology.

How does Burst Mode operation affect noise performance in the LTC1682IS8#TRPBF?

Burst Mode activates automatically when output current falls below ~100µA, disabling the 550kHz oscillator to reduce quiescent current to 150µA. While this improves efficiency, it increases output noise: 58µV_RMS (10Hz–100kHz) rises to ~800µV_P-P (10Hz–2.5MHz) during burst intervals. For ultra-low-noise VCO biasing, operate above 100µA or use external filtering; Burst Mode is best reserved for standby/sleep states where noise is not critical.

Is the LTC1682IS8#TRPBF pin-compatible with other variants in the LTC1682 family?

Yes, all LTC1682 variants-including LTC1682IS8#TRPBF (3.3V), LTC1682IS8-5 (5V), and LTC1682IS8 (adjustable)-share identical 8-pin SO package, pinout, and footprint. The only functional difference is the internal feedback network on Pin 3 (FILT for fixed versions, FB for adjustable). This allows direct substitution in existing layouts when changing output voltage requirements, provided external components (e.g., FILT capacitor) match the variant's specification.