Analog Devices Inc. LTC1474CMS8-3.3#PBF

Overview

LTC1474CMS8-3.3#PBF from Analog Devices (formerly Linear Technology) is a high-efficiency, low-quiescent-current step-down DC/DC converter with integrated 1.4Ω P-channel MOSFET switch, fixed 3.3V output, and 8-lead MSOP package. It delivers up to 250mA output current, achieves >92% peak efficiency at 10V input, draws only 10µA no-load supply current, and supports 4V–18V input range - ideal for battery-powered portable instrumentation and wireless modems.

For engineers reviewing the LTC1474CMS8-3.3#PBF datasheet, LTC1474CMS8-3.3#PBF pinout, LTC1474CMS8-3.3#PBF application, or LTC1474CMS8-3.3#PBF equivalent, key selection considerations include its 3.3V fixed output accuracy (±2%), programmable current limit (325–400mA), 100% duty-cycle low-dropout operation, active-low micropower shutdown (6µA), and functional low-battery detector active during shutdown.

Technical Context

The LTC1474CMS8-3.3#PBF employs Burst Mode™ operation to maintain regulation while minimizing quiescent current: it alternates short energy bursts (with 4.75µs minimum off-time) and deep-sleep cycles where only voltage comparator, 1.23V reference, and low-battery comparator remain active. Its internal current sense architecture uses a 5% current-mirrored MOSFET and 100mV trip threshold to enable precise peak current control via optional external R_SENSE.

Unlike the LTC1475 variant, the LTC1474CMS8-3.3#PBF implements logic-controlled shutdown via RUN pin (0.4–1.0V threshold), not pushbutton on/off. Its LBI/LBO pins provide independent low-battery monitoring with 1.23V internal reference and 5mV hysteresis, fully operational in shutdown mode - critical for long-life battery systems requiring state-aware power management.

Key Specifications

Pinout & Package

Package: 8-lead MSOP (3mm × 3mm, 0.65mm pitch), RoHS-compliant, moisture-sensitive level 1. Thermal resistance θ_JA = 150°C/W - requires minimal PCB copper area for thermal management in space-constrained designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC1474CMS8-3.3#PBF, TPS62231DRYR offers smaller footprint but sacrifices 4V–18V flexibility and low-battery monitoring; MAX17222ETA+ achieves ultra-low IQ but cannot replace LTC1474CMS8-3.3#PBF in wide-input or battery-state-aware designs.

Availability

LTC1474CMS8-3.3#PBF is available at Aetrix Electronics and suitable for cellular telephones, portable instruments, and wireless modems requiring stable component supply across automotive, industrial, and medical production lifecycles.

Supply support for LTC1474CMS8-3.3#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision instrumentation, communications, and industrial markets.

The LTC1474 series was designed specifically for moderate-current (≤300mA), battery-operated applications demanding ultra-low quiescent current, wide input range, and integrated protection - emphasizing longevity, reliability, and minimal external component count.

FAQ

What is the maximum continuous output current of the LTC1474CMS8-3.3#PBF?

The LTC1474CMS8-3.3#PBF delivers up to 250mA continuous output current under typical conditions (T_A = 25°C, 100µH inductor, MBR0530 diode). Its peak switch current limit is 325–400mA (R_SENSE = 0Ω), but sustained 250mA requires adequate PCB copper area and ambient temperature ≤70°C to maintain junction temperature below 125°C.

Does the LTC1474CMS8-3.3#PBF support 100% duty cycle operation, and what is its practical dropout voltage?

Yes, the LTC1474CMS8-3.3#PBF supports 100% duty cycle operation, enabling regulation down to V_OUT + V_DS(on) ≈ 3.3V + 0.35V = 3.65V at 250mA (based on 1.4Ω R_DS(on)). This allows functional operation even as input voltage sags near the 3.3V output rail - critical for maintaining system uptime in aging battery applications.

How does the low-battery detector function in shutdown mode for the LTC1474CMS8-3.3#PBF?

The low-battery detector in the LTC1474CMS8-3.3#PBF remains fully operational during shutdown: the internal 1.23V reference and comparator continue monitoring the LBI pin voltage. When LBI falls below 1.23V, LBO sinks current - enabling external circuitry (e.g., microcontroller or LED) to respond to battery depletion without waking the main regulator.

Can the LTC1474CMS8-3.3#PBF be used with an external current sense resistor, and what is the minimum programmable current limit?

Yes, the LTC1474CMS8-3.3#PBF supports external R_SENSE between SENSE and VIN pins to program peak current from 325mA down to 10mA. Using R_SENSE = 10Ω yields ~10mA limit (per Figure 2), enabling optimization for ultra-low-power sensors. For values <1Ω, parallel standard 0603 resistors are recommended over specialized shunts.

What is the purpose of the RUN pin on the LTC1474CMS8-3.3#PBF, and what voltage levels enable/disable operation?

On the LTC1474CMS8-3.3#PBF, the RUN pin controls logic-based enable/disable: open or pulled above 0.7V enables operation (10µA IQ), while grounding it forces shutdown (6µA IQ). Its 0.4–1.0V threshold range provides noise margin against spurious transitions, and no external pull-up is required due to internal biasing.