Analog Devices Inc. LTC3525DESC6-3.3#PBF

Overview

LTC3525DESC6-3.3#PBF from Analog Devices (formerly Linear Technology) is a micropower synchronous step-up DC/DC converter optimized for single-cell alkaline/NiMH or Li-Ion battery systems. It starts up from 0.85V input, delivers fixed 3.3V output with pass-through mode in shutdown, supports up to 140mA load at 1.8V input, and achieves up to 95% efficiency. It serves as a compact, high-efficiency replacement for charge pumps in portable medical and instrumentation devices.

For engineers reviewing the LTC3525DESC6-3.3#PBF datasheet, LTC3525DESC6-3.3#PBF pinout, LTC3525DESC6-3.3#PBF application, or LTC3525DESC6-3.3#PBF equivalent, key selection criteria include ultralow 7µA quiescent current, SC70-6 package footprint, pass-through mode behavior, 0.5Ω NMOS/0.8Ω PMOS switch R_DS(on), and guaranteed operation down to –40°C ambient.

Technical Context

The LTC3525DESC6-3.3#PBF employs Burst Mode® operation with hysteretic control to maintain regulation at light loads while minimizing quiescent current. Its internal architecture integrates a 0.5Ω N-channel MOSFET switch and 0.8Ω P-channel synchronous rectifier, enabling bidirectional conduction during startup and pass-through mode.

Unlike standard boost converters, it features automatic peak/valley inductor current adjustment (150mA–400mA range), anti-ringing control across SW–VIN, and thermal shutdown protection. The device powers itself from VIN until VOUT exceeds VIN + 0.2V, then transitions to VOUT-derived supply-enabling stable regulation even when VIN ≥ VOUT.

Key Specifications

Pinout & Package

Package: 6-Lead Plastic SC70 (SC6), 2.0mm × 1.25mm × 1.0mm, lead-free, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous step-up converter applications.

Compared with LTC3525-3.3#PBF, the LTC3525DESC6-3.3#PBF uniquely enables pass-through mode instead of output disconnect-critical for systems requiring uninterrupted rail coupling during sleep. Versus LTC3429#PBF, it trades peak current capability for 3× lower IQ and simpler external component count, making it optimal for ultra-low-power, space-constrained applications.

Availability

LTC3525DESC6-3.3#PBF is available at Aetrix Electronics and suitable for glucose monitoring systems, portable digital instruments, MP3 players, and low-power digital cameras requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LTC3525DESC6-3.3#PBF 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 legacy products, including precision power management ICs.

The LTC3525D product line was designed specifically for micropower, single-cell battery-powered applications demanding minimal quiescent current, small footprint, and robust start-up from depleted cells-targeting portable medical, instrumentation, and consumer electronics.

FAQ

What is the minimum input voltage required for the LTC3525DESC6-3.3#PBF to start switching?

The LTC3525DESC6-3.3#PBF starts switching with an input voltage as low as 0.85V. This allows reliable operation from a single alkaline or NiMH cell near end-of-life. Once started, it can sustain regulation down to 0.5V input depending on load current, per the Electrical Characteristics table and Typical Performance curves.

How does pass-through mode function in the LTC3525DESC6-3.3#PBF during shutdown?

In shutdown (SHDN < 0.4V), the LTC3525DESC6-3.3#PBF turns on its internal P-channel MOSFET, connecting VIN to VOUT through the external inductor. This creates a low-impedance path (<1Ω total) that maintains VOUT at approximately VIN level-enabling system-level rail continuity without external components.

What external components are required for basic operation of the LTC3525DESC6-3.3#PBF?

The LTC3525DESC6-3.3#PBF requires only three external components: a 10µH inductor (e.g., Murata LQH32CN100K53), a 10µF ceramic output capacitor (X5R/X7R), and a 1µF ceramic input bypass capacitor. No feedback resistors or compensation network is needed due to its fixed 3.3V output and internal regulation.

What is the maximum continuous output current supported by the LTC3525DESC6-3.3#PBF at 1.8V input?

At 1.8V input, the LTC3525DESC6-3.3#PBF delivers up to 140mA continuous output current while maintaining 3.3V regulation within specification. This value is confirmed in the "Typical Application" section and "Maximum Output Current vs VIN" graph (Figure G01), where VOUT drops ≤2.5% at 140mA with VIN = 1.8V.

Does the LTC3525DESC6-3.3#PBF require special PCB layout considerations for thermal performance?

Yes-the LTC3525DESC6-3.3#PBF has θ_JA = 150°C/W on board over ground plane. To ensure safe operation at full load, use a minimum 25mm² copper pour connected to Pins 2 and 5 (GND) as a thermal pad, keep high-current paths short, and avoid placing thermal vias under the IC body unless using multi-layer stackup with dedicated ground planes.