Analog Devices Inc. LTC1682IS8-3.3#TRPBF

Overview

LTC1682IS8-3.3#TRPBF from Analog Devices (formerly Linear Technology) is a fixed-output 3.3V doubler charge pump with integrated low-noise LDO regulator, designed for powering noise-sensitive RF circuitry such as VCOs in wireless transceivers. 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 LTC1682IS8-3.3#TRPBF datasheet, LTC1682IS8-3.3#TRPBF pinout, LTC1682IS8-3.3#TRPBF application, or LTC1682IS8-3.3#TRPBF equivalent, key selection considerations include its guaranteed –40°C to 85°C industrial temperature range, 3.30V ±0.07V regulated output tolerance at 1mA load, 1µA shutdown current, internal thermal/short-circuit protection, and compatibility with small ceramic capacitors (no inductors required).

Technical Context

The LTC1682IS8-3.3#TRPBF integrates a switched-capacitor voltage doubler and a low-dropout linear regulator in a single 8-pin SO package. The charge pump generates ~2×VIN at CPO, which feeds the LDO stage; regulation is achieved via an internal 1.235V reference and trimmed oscillator, with no external feedback resistors needed for the fixed 3.3V version.

Its architecture enables stable operation with ≥2µF ceramic output capacitance, supports Burst Mode below 100µA load to reduce quiescent current to 150µA, and incorporates power-on reset, thermal shutdown at 150°C, and internal current limiting-ensuring robustness in portable RF power supply applications.

Key Specifications

Pinout & Package

Package: 8-lead plastic SO (narrow, 0.150-inch width), RoHS-compliant, surface-mount. Pin pitch: 1.27mm. Thermal resistance θ_JA = 140°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-noise boosted supply applications.

Compared with LTC1682CS8-3.3, the LTC1682IS8-3.3#TRPBF provides verified industrial temperature support essential for outdoor or automotive-adjacent wireless modules; versus LT3467ES6-3.3, it trades output current headroom for significantly lower noise and inductor-free simplicity in RF bias applications.

Availability

LTC1682IS8-3.3#TRPBF is available at Aetrix Electronics and suitable for cellular phone VCO power supplies, wireless PCMCIA card designs, and portable medical instrument sensor biasing requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LTC1682IS8-3.3#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, documentation, and manufacturing continuity for all LTC legacy parts.

The LTC1682 family was designed specifically to replace inefficient discrete charge pump + LDO solutions in RF power management, targeting noise-sensitive wireless infrastructure and portable communications equipment.

FAQ

What is the minimum input voltage required for stable 3.3V output from the LTC1682IS8-3.3#TRPBF?

The LTC1682IS8-3.3#TRPBF requires a minimum input voltage of 2.0V to maintain regulation at 3.3V output across its full industrial temperature range (–40°C to +85°C). Below 2.0V, the internal LDO may drop out, allowing CPO ripple to appear at VOUT. This specification is explicitly defined in the Electrical Characteristics table under "VIN Operating Voltage" for the -3.3 variant.

Does the LTC1682IS8-3.3#TRPBF require external feedback resistors to set its output voltage?

No, the LTC1682IS8-3.3#TRPBF does not require external feedback resistors. It uses an internal resistor divider to fix the output at 3.3V, with Pin 3 designated as FILT (not FB) for connecting a 1nF noise-filtering capacitor to ground. External resistors are only needed for the adjustable LTC1682 version (without -3.3 suffix).

How does Burst Mode operation affect noise performance in the LTC1682IS8-3.3#TRPBF?

Burst Mode reduces quiescent current to ~150µA at light loads (<100µA) but increases output noise: the 58µV_RMS spec applies in continuous mode. In Burst Mode, measured noise rises to ~500µV_P-P (10Hz–2.5MHz) due to intermittent switching. For ultra-low-noise VCO bias, operate above 100µA or disable Burst Mode if supported by system load profile.

Can the LTC1682IS8-3.3#TRPBF safely drive a 50mA continuous load at 85°C ambient?

Yes, the LTC1682IS8-3.3#TRPBF is rated for 50mA continuous output across its full –40°C to +85°C junction temperature range. Thermal calculations using θ_JA = 140°C/W confirm safe operation at 85°C ambient with typical PCB copper area; internal thermal shutdown activates only above 150°C junction temperature, providing margin.

What capacitor values are mandatory for stable operation of the LTC1682IS8-3.3#TRPBF?

Mandatory capacitors for the LTC1682IS8-3.3#TRPBF are: 0.22µF ceramic flying capacitor (C1) between C+ and C–; ≥2µF low-ESR ceramic at VOUT (C2); ≥2µF low-ESR ceramic at CPO (C3); and 1nF ceramic from FILT to GND. Input VIN requires ≥2µF low-ESR ceramic (C4). All values are specified in the Applications Information section and validated in Typical Application circuits.