Analog Devices Inc. LTC1502IS8-3.3#TRPBF

Overview

LTC1502IS8-3.3 from Analog Devices (formerly Linear Technology) is a regulated quadrupler charge pump DC/DC converter designed to generate a stable 3.3V output from a single alkaline or NiCd cell (0.9V–1.8V input). It delivers up to 10mA output current, features 40µA operating current and 5µA shutdown current, and requires no inductors-only five external capacitors. It is used in space-constrained, battery-powered medical and portable instrumentation.

For engineers reviewing the LTC1502IS8-3.3 datasheet, LTC1502IS8-3.3 pinout, LTC1502IS8-3.3 application, or LTC1502IS8-3.3 equivalent, key selection criteria include guaranteed 0.9V start-up, ±4% output regulation at 3.3V, 8-pin MSOP industrial-grade packaging, short-circuit protection, and shutdown-controlled load isolation.

Technical Context

The LTC1502IS8-3.3 implements a two-stage cascaded doubler architecture: CP1 doubles VIN onto C2, which then serves as the input for CP2 to quadruple the voltage to VOUT. Regulation is achieved via hysteretic comparison of a divided VOUT against a 1.2V internal reference, enabling clock gating to maintain 3.3V ±4% under load.

Startup is enhanced by COMP2, which monitors the divided C2 voltage versus VIN and disables CP2 until C2 exceeds VIN-ensuring sufficient gate drive voltage before enabling the output stage. Shutdown is controlled asynchronously via sampling of the C1–/SHDN pin every 16 clock cycles (500kHz oscillator), with internal pull-up ensuring return to active mode when external pull-down is removed.

Key Specifications

Pinout & Package

Package: 8-lead plastic MSOP (MS8), industrial temperature range (–40°C to +85°C), JEDEC MO-187 variant, 3.0mm × 3.0mm footprint, 0.65mm lead pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar regulated charge pump DC/DC converter applications.

Compared with LTC1517-3.3 and LTC1682, the LTC1502IS8-3.3 uniquely combines sub-1V start-up, integrated shutdown, and quadrupling gain in an industrial-grade MSOP package-making it the only option validated for single-cell alkaline/NiCd operation down to 0.9V with load isolation.

Availability

LTC1502IS8-3.3 is available at Aetrix Electronics and suitable for pagers, battery backup supplies, and handheld medical instruments requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LTC1502IS8-3.3 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 legacy Linear parts including the LTC series.

The LTC1502IS8-3.3 belongs to Linear's micropower charge pump DC/DC converter family, engineered specifically for ultra-low-voltage, single-cell battery applications where inductor-free design, minimal PCB area, and guaranteed start-up are mandatory.

FAQ

What is the minimum input voltage required for the LTC1502IS8-3.3 to start up and regulate?

The LTC1502IS8-3.3 guarantees start-up at 0.9V across its full industrial temperature range (–40°C to +85°C). At –40°C to +85°C, the minimum start-up voltage is specified at 1.1V; however, the 0.9V guarantee applies over 0°C to +70°C with 100kΩ load on VOUT. This makes the LTC1502IS8-3.3 uniquely capable of powering systems from near-dead alkaline cells. The LTC1502IS8-3.3 achieves this via COMP2-assisted startup that delays CP2 activation until C2 reaches sufficient voltage.

Does the LTC1502IS8-3.3 require external inductors?

No, the LTC1502IS8-3.3 is a capacitor-based charge pump converter and requires zero inductors. It uses two external flying capacitors (C1 and C3, typically 0.47–2.2µF ceramic) and three external storage/bypass capacitors (CIN, C2, and COUT, each ≥10µF low-ESR). This eliminates magnetic components, simplifies layout, and reduces EMI-key advantages for portable and medical applications. The LTC1502IS8-3.3 relies entirely on switched-capacitor voltage multiplication.

How does shutdown work on the LTC1502IS8-3.3, and what happens to the load during shutdown?

Shutdown is activated by pulling the C1–/SHDN pin (Pin 3) below 0.2V using an external pull-down device (e.g., open-drain FET or resistor). During shutdown, the internal oscillator stops, CP1 and CP2 switches enter high-impedance states, and VOUT is actively disconnected from VIN-preventing backfeed and eliminating load current draw from the battery. The LTC1502IS8-3.3 draws only 5µA in this state. Release of the pin allows the internal 2.5µA pull-up to restore operation within 20–50µs.

Is the LTC1502IS8-3.3 protected against output short circuits?

Yes, the LTC1502IS8-3.3 provides indefinite short-circuit protection on VOUT. When shorted to ground, it limits output current to under 20mA by cycling CP2 enable/disable based on C2 voltage monitoring-preventing thermal damage or latch-up. The part resumes normal regulation immediately upon short removal, with no reset or recovery delay. This behavior is verified across the full –40°C to +85°C range and is intrinsic to the COMP2-controlled startup architecture. The LTC1502IS8-3.3 does not require external current-limiting components.

What package and temperature grade does the LTC1502IS8-3.3 use?

The LTC1502IS8-3.3 uses the 8-lead plastic MSOP (MS8) package, measuring 3.0mm × 3.0mm with 0.65mm lead pitch, and is rated for the industrial temperature range of –40°C to +85°C. Its part number suffix "I" denotes industrial grade, and "S8" confirms the MSOP package-distinct from the SO-8 version (LTC1502CS8-3.3). The MS8 package supports high-density layouts and offers superior thermal performance (θ_JA = 250°C/W) compared to SO-8, making it preferred for thermally constrained medical and portable designs. The LTC1502IS8-3.3 is fully RoHS compliant and Pb-free.