Analog Devices Inc. LTC3525ISC6-3.3#TRPBF

Overview

LTC3525ISC6-3.3#TRPBF from Analog Devices (formerly Linear Technology) is a micropower synchronous step-up DC/DC converter with output disconnect, designed for single-cell alkaline/NiMH or Li-Ion battery-powered systems. It starts up from as low as 0.85V input, delivers fixed 3.3V output, achieves up to 95% efficiency at 60mA load from 1.2V input, and operates in Burst Mode® with 7µA quiescent current - enabling ultra-long battery life in portable medical and instrumentation devices.

For engineers reviewing the LTC3525ISC6-3.3#TRPBF datasheet, LTC3525ISC6-3.3#TRPBF pinout, LTC3525ISC6-3.3#TRPBF application, or LTC3525ISC6-3.3#TRPBF equivalent, key selection criteria include input start-up voltage (0.85V), output disconnect capability, thermal shutdown behavior, SC70-6 package footprint, and compatibility with 10µH inductors and 10–22µF ceramic output capacitors.

Technical Context

The LTC3525ISC6-3.3#TRPBF employs a hysteretic Burst Mode® control architecture with adaptive peak/valley inductor current regulation (150mA–400mA range), enabling high efficiency across light-to-moderate loads. Its internal 0.5Ω N-channel switch and 0.8Ω P-channel synchronous rectifier eliminate external diode requirements while supporting true output disconnect during shutdown.

Startup uses a dedicated oscillator to bootstrap operation below 1V; once VOUT exceeds VIN by ≥0.2V and either rail reaches ≥1.8V, it transitions to normal synchronous operation. Antiringing control on the SW node minimizes EMI, and thermal shutdown activates above 125°C junction temperature.

Key Specifications

Pinout & Package

Package: 6-Lead Plastic SC70 (SC6), 1.0mm max height, 2.0mm × 1.25mm footprint - optimized for ultra-thin portable electronics.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous boost converter applications.

Compared with LTC3429ESC6-3.3#TRMPBF and LTC3528EDDB-3.3#TRMPBF, the LTC3525ISC6-3.3#TRPBF delivers the lowest quiescent current (7µA) in the smallest SC70-6 footprint, making it uniquely suited for space- and energy-constrained applications where 140mA output suffices and battery life is paramount.

Availability

LTC3525ISC6-3.3#TRPBF is available at Aetrix Electronics and suitable for portable medical sensors, low-power instrumentation, digital audio players, and wireless sensor nodes requiring stable component supply with guaranteed long-term availability.

Supply support for LTC3525ISC6-3.3#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 technical and manufacturing continuity for all Linear power products.

The LTC3525 family was designed specifically for micropower, single-cell battery-powered applications demanding high efficiency at ultra-light loads and minimal external component count - targeting portable healthcare, instrumentation, and consumer electronics.

FAQ

What is the minimum input voltage required for LTC3525ISC6-3.3#TRPBF to start switching?

The LTC3525ISC6-3.3#TRPBF requires a minimum input voltage of 0.85V to initiate startup oscillation and begin regulation. Once started, it can maintain regulation down to ~0.5V depending on load current. This enables full utilization of single alkaline or NiMH cells throughout their discharge curve. The LTC3525ISC6-3.3#TRPBF achieves this via an integrated start-up oscillator and low-threshold comparators.

Does LTC3525ISC6-3.3#TRPBF support operation when VIN is greater than VOUT?

Yes, the LTC3525ISC6-3.3#TRPBF supports VIN ≥ VOUT operation. When VIN exceeds VOUT, the internal P-channel synchronous rectifier is disabled, and the device operates in pass-through mode with reduced efficiency and lower output current capability. The LTC3525ISC6-3.3#TRPBF maintains regulation but does not provide synchronous rectification in this mode - confirmed in the "Operation" section of the datasheet.

What is the purpose of the dual GND pins (Pins 2 and 5) on LTC3525ISC6-3.3#TRPBF?

The dual GND pins (Pins 2 and 5) on the LTC3525ISC6-3.3#TRPBF reduce ground path impedance and improve thermal conduction from the die to the PCB. Pin 2 serves as the primary reference for SHDN and internal circuitry, while Pin 5 carries high-frequency switch return current. Separating these paths minimizes noise coupling and enhances stability - a design requirement explicitly noted in the "Component Selection" section of the LTC3525ISC6-3.3#TRPBF datasheet.

How does the LTC3525ISC6-3.3#TRPBF achieve 95% efficiency with only three external components?

The LTC3525ISC6-3.3#TRPBF achieves up to 95% efficiency using an integrated synchronous rectifier (0.5Ω NMOS + 0.8Ω PMOS), eliminating Schottky diode losses, and adaptive Burst Mode® control that scales peak inductor current from 150mA to 400mA based on load. With only an inductor, input capacitor, and output capacitor required, conduction and switching losses are minimized across the operating range - verified in Figure 3525 G04 of the LTC3525ISC6-3.3#TRPBF datasheet.

What happens to the output voltage during LTC3525ISC6-3.3#TRPBF shutdown?

During shutdown (SHDN < 0.4V), the LTC3525ISC6-3.3#TRPBF disconnects VOUT from VIN using its internal PMOS switch, resulting in true output isolation. VOUT decays only due to load and capacitor leakage - no backfeed occurs. This feature prevents inrush current at startup and allows safe hot-swap of batteries. The LTC3525ISC6-3.3#TRPBF maintains <1µA shutdown current, preserving battery charge during extended idle periods.