Semtech Corporation SC2604ULTRT

Overview

SC2604ULTRT from Semtech is a voltage-mode PWM boost controller with input disconnect FET drive, designed for 4.5V–16V input DC/DC conversion. It delivers up to 95% efficiency at 400kHz switching frequency, features 1% reference accuracy, programmable soft start, and hiccup-mode over-current protection. It serves in auxiliary supplies and high-density portable power rails.

For engineers reviewing the SC2604ULTRT datasheet, pinout, applications, or equivalent options, key selection criteria include its MLPD-UT8 package thermal performance (50°C/W), 800mA gate drive capability, input disconnect control via DRV pin, and integrated compensation eliminating external loop components.

Technical Context

The SC2604ULTRT implements a fixed-frequency voltage-mode control architecture with internal ramp generation and an error amplifier referenced to a 1.25V ±1% bandgap. Its PWM comparator compares the error amplifier output against a 400kHz sawtooth ramp to generate duty-cycle-modulated gate signals.

It integrates dual gate drivers: GATE drives the main boost switch (N-channel MOSFET) with 0.8A source/sink capability, while DRV drives an external N-channel input disconnect FET using a charge-pump floating driver. Hiccup-mode OCP is triggered by CS pin voltage exceeding 72mV, initiating automatic retry via OCP/EN capacitor discharge/charge cycling.

Key Specifications

Pinout & Package

SC2604ULTRT is packaged in a 2 mm × 3 mm × 0.6 mm MLPD-UT8 thermally enhanced lead-free, halogen-free RoHS-compliant package with exposed thermal pad connected to ground.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM3478MM/NOPB and TPS40210DRCT, SC2604ULTRT uniquely integrates input disconnect FET drive (DRV), hiccup-mode OCP, and internal compensation-reducing component count and simplifying fault-tolerant boost design in space- and reliability-sensitive applications.

Availability

SC2604ULTRT is available at Aetrix Electronics and suitable for portable devices, flat panel TV auxiliary supplies, and industrial power supply designs requiring stable component supply, RoHS compliance, and thermal-efficient MLPD-UT8 packaging.

Supply support for SC2604ULTRT 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

Semtech Corporation is a U.S.-based fabless semiconductor company specializing in high-performance analog and mixed-signal ICs for power management, RF, and signal integrity markets.

The SC2604 product line was developed for cost-sensitive, high-efficiency boost DC/DC applications in portable, consumer, and industrial equipment where input disconnect, hiccup protection, and small-footprint integration are critical.

FAQ

What is the maximum recommended output current for SC2604ULTRT in a typical 12V-to-25V boost application?

The SC2604ULTRT supports up to 1.5 A output current in validated 12V-to-25V designs (e.g., Figure 1 and BOM on page 12), assuming proper thermal management via the MLPD-UT8 exposed pad and appropriate external MOSFET selection (e.g., AO4412). Peak inductor current is limited by the 72 mV CS threshold, so actual output depends on efficiency, layout, and ambient conditions. SC2604ULTRT's 0.8 A GATE drive and 50°C/W thermal resistance define practical continuous load limits.

Does SC2604ULTRT support adjustable switching frequency?

No, SC2604ULTRT operates at a fixed 400 kHz nominal switching frequency, with tolerance of ±20% (320–480 kHz) over temperature and supply. The oscillator is fully internal with no external frequency-setting components. This simplifies design and EMI filtering but precludes frequency tuning for noise avoidance or efficiency optimization. SC2604ULTRT's fixed frequency is specified in the Electrical Characteristics table on page 3 of the datasheet.

How does the SC2604ULTRT implement input disconnect, and what FET parameters are critical for DRV pin compatibility?

The SC2604ULTRT implements input disconnect via the DRV pin, which drives the gate of an external N-channel MOSFET placed between the input source and the boost stage. Critical FET parameters include V_GS(th) ≤ 2.5 V (to ensure turn-on at low VIN), low Q_g, and R_DS(on) optimized for expected load current. At VIN < 7.5 V, DRV headroom decreases, requiring low-threshold FETs like the IRF7821. SC2604ULTRT's DRV provides 45 µA sink/source, sufficient for such devices without buffering.

Can SC2604ULTRT operate with an input voltage below 4.5 V?

SC2604ULTRT has an absolute minimum VIN rating of 4.5 V per Recommended Operating Conditions, and its UVLO rising threshold is 4.2 V typical. Operation below 4.5 V is outside specification and may result in unstable regulation, reduced gate drive, or failure to initiate soft start. While the device may power up at 4.2 V, performance-including reference accuracy, OCP threshold, and efficiency-is not guaranteed. For sub-4.5 V inputs, consider alternative controllers such as the SC4519 or TPS61088.

What is the purpose of the OCP/EN pin beyond over-current protection?

Beyond hiccup-mode over-current protection, the OCP/EN pin serves as a dual-function enable/control node: pulling it below 590 mV disables both the DRV and GATE drivers, providing a hardware shutdown input; connecting a capacitor sets the hiccup off-time and controls in-rush current during startup. Its internal 37 µA charge and 1 µA discharge currents form a timing oscillator that governs fault recovery intervals. This makes SC2604ULTRT suitable for applications requiring controlled power sequencing or remote enable/disable capability.