Analog Devices Inc. LTC1504IS8-3.3#TRPBF

Overview

LTC1504IS8-3.3#TRPBF from Analog Devices (formerly Linear Technology) is a fixed-output 3.3V, 500mA synchronous step-down DC/DC regulator in an SO-8 package. It integrates dual on-chip 1.5Ω MOSFETs, operates from 4V–10V input, delivers up to 92% peak efficiency, and features internal 1% reference accuracy with source/sink capability for tight load regulation in portable digital systems.

For engineers reviewing the LTC1504IS8-3.3#TRPBF datasheet, LTC1504IS8-3.3#TRPBF pinout, LTC1504IS8-3.3#TRPBF application, or LTC1504IS8-3.3#TRPBF equivalent, key selection criteria include its fixed 3.3V output, 200kHz switching frequency (synchronizable to 500kHz), adjustable current limit via IMAX pin, soft-start control, and thermal performance in SO-8 under 500mA continuous load.

Technical Context

The LTC1504IS8-3.3#TRPBF implements a synchronous buck architecture with integrated P-channel high-side and N-channel low-side MOSFETs. Its feedback loop uses direct SENSE-pin monitoring at 3.3V (±3.4% over temperature), supported by MIN/MAX comparators for ±3% transient override and a transconductance error amplifier (gmV = 350–1100 µmho).

Current limiting is implemented via an ILIM amplifier comparing SW-node voltage during Q1 conduction against a resistor-set threshold at IMAX; soft-start timing and current-limit response are jointly governed by the external SS capacitor. The internal 200kHz sawtooth oscillator drives non-overlapping gate logic, with duty cycle limited to 84–90% maximum.

Key Specifications

Pinout & Package

Package: 8-lead plastic SO-8 (S8), exposed pad not present; JEDEC MS-012AC compliant; θJA = 90°C/W; TJMAX = 115°C.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output synchronous buck regulator applications.

Compared with TPS62231DRVR and MP2104DQ-LF-Z, the LTC1504IS8-3.3#TRPBF offers superior output accuracy (±1.2% vs ±2%), dedicated transient protection (MIN/MAX comparators), and proven 500mA capability in SO-8 - making it optimal for applications prioritizing voltage stability and robustness over ultra-small size or lowest VIN.

Availability

LTC1504IS8-3.3#TRPBF is available at Aetrix Electronics and suitable for portable digital systems, active termination networks, auxiliary output voltage supplies, and minimum-part-count switcher designs requiring stable component supply, long-term lifecycle support, and guaranteed parametric performance.

Supply support for LTC1504IS8-3.3#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, Inc. (ADI) is a global semiconductor leader specializing in high-performance analog, mixed-signal, and power management ICs for precision, reliability, and efficiency-critical applications.

The LTC1504 product line was developed by Linear Technology (acquired by ADI in 2017) to deliver compact, self-contained synchronous buck regulators for space- and thermal-constrained portable and industrial systems demanding high efficiency and simple implementation.

FAQ

What is the guaranteed input voltage range for LTC1504IS8-3.3#TRPBF?

The LTC1504IS8-3.3#TRPBF is specified for 4V to 10V input operation per its Absolute Maximum Ratings and Electrical Characteristics tables. While Linear Technology notes that guaranteed specifications at 2.7V require factory consultation, the device is not rated for reliable operation below 4V - attempting sub-4V use may result in dropout, instability, or undefined behavior.

Does LTC1504IS8-3.3#TRPBF require external feedback resistors?

No. The LTC1504IS8-3.3#TRPBF is the fixed 3.3V version and uses an internal resistor divider connected to the SENSE pin. Unlike the adjustable LTC1504CS8 variant, it requires no external FB resistors - SENSE connects directly to the output node, simplifying design and improving accuracy by eliminating resistor tolerance errors.

How does the current limit function work on LTC1504IS8-3.3#TRPBF?

The LTC1504IS8-3.3#TRPBF implements current limiting via the IMAX pin: an internal 12µA current source pulls down through an external resistor to set a voltage threshold. The ILIM amplifier compares this voltage to the SW-node voltage during high-side switch conduction. When exceeded, ILIM sinks current from the SS pin, reducing COMP voltage and duty cycle - enabling programmable, resistor-set overload protection without external sense resistors.

Can LTC1504IS8-3.3#TRPBF be synchronized to an external clock?

Yes. The LTC1504IS8-3.3#TRPBF's internal oscillator can be synchronized to an external clock signal up to 500kHz. This is achieved by injecting a clean square wave into the COMP pin, overriding the internal 200kHz sawtooth generator. Synchronization helps eliminate beat frequencies in multi-rail systems and reduces EMI by aligning switching edges across multiple converters.

What thermal considerations apply to LTC1504IS8-3.3#TRPBF at 500mA?

At 500mA continuous load with 5V input, the LTC1504IS8-3.3#TRPBF dissipates ~0.85W (calculated from 92% efficiency). With θJA = 90°C/W, junction temperature rise is ~77°C above ambient - requiring adequate copper pour on GND pin and airflow or derating above 25°C ambient. For sustained 500mA operation, keep ambient ≤50°C or add thermal vias under the SO-8 body.