Analog Devices Inc. LTC3721EUF-1#PBF

Overview

LTC3721EUF-1#PBF from Analog Devices (formerly Linear Technology) is a high-efficiency push-pull PWM controller IC designed for isolated DC/DC power converters. It delivers peak current mode control, programmable dead-time (90–300 ns), adjustable leading edge blanking (40–320 ns), and 1.5A sink / 1A source MOSFET drivers. It operates up to 1 MHz (CT oscillator) and supports telecom infrastructure and server power supplies requiring compact, reliable isolation.

For engineers reviewing the LTC3721EUF-1#PBF datasheet, LTC3721EUF-1#PBF pinout, LTC3721EUF-1#PBF application, or LTC3721EUF-1#PBF equivalent, this page provides verified technical context, package-specific pin mapping, real-world application constraints, and validated alternative options - all grounded in the official Linear Technology/LTC3721-1 datasheet (SN37211 FS Rev. C).

Technical Context

The LTC3721EUF-1#PBF implements true peak current mode control with single-resistor slope compensation and 100 ns leading edge blanking delay (programmable via RLEB). Its dual 180° out-of-phase outputs (DRVA/DRVB) drive external N-channel MOSFETs in push-pull topology with independently adjustable dead-time via DPRG–VREF resistor network.

It integrates a 5.0V ±1% reference (18 mA capable), 10.25V VCC shunt regulator (40 mA sink), and dual protection architecture: cycle-by-cycle current limiting at 300 mV on CS and hiccup-mode shutdown at 600 mV. Operating temperature range is –40°C to +85°C with 125°C junction limit.

Key Specifications

Pinout & Package

Package: 16-lead (4 mm × 4 mm) plastic QFN with exposed thermal pad (Pin 17 = GND, must be soldered to PCB ground plane). Pin pitch: 0.5 mm. RoHS-compliant, lead-free (PbF).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar push-pull controller applications.

Compared with UCC2897A and MAX5069A, the LTC3721EUF-1#PBF uniquely combines programmable dead-time, leading edge blanking, integrated 5 V reference, and VCC shunt regulation - making it the only option among the three qualified for high-reliability, transformer-isolated push-pull converters demanding precise timing control and minimal external components.

Availability

LTC3721EUF-1#PBF is available at Aetrix Electronics and suitable for telecom infrastructure power, distributed power architecture, and server power supplies requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LTC3721EUF-1#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 product continuity, documentation, and support for the LTC portfolio. Linear pioneered high-performance analog and power management ICs for demanding industrial and communications applications.

The LTC3721-1 product line was specifically engineered for isolated push-pull DC/DC converters in space-constrained, high-efficiency systems - emphasizing robust gate drive, precise current sensing, and flexible protection features without external complexity.

FAQ

What is the maximum operating frequency of the LTC3721EUF-1#PBF?

The LTC3721EUF-1#PBF oscillator supports up to 1 MHz on the CT pin, but its push-pull outputs switch at half that frequency - i.e., maximum 500 kHz. This limitation arises from the internal 2× frequency division inherent to push-pull topology generation. The datasheet confirms 47–50% maximum duty cycle and 220–280 kHz typical oscillator range with 270 pF CT, scalable to 1 MHz with appropriate capacitor selection.

Does the LTC3721EUF-1#PBF require an external VCC supply or can it self-bias?

The LTC3721EUF-1#PBF includes an integrated 10.25 V shunt regulator on the VCC pin, enabling self-bias from an auxiliary transformer winding or pre-regulated rail. It draws only 230 µA at startup, allowing high-value start-up resistors (e.g., 430 kΩ for off-line inputs). Once enabled, VCC can drop to ~6 V while maintaining operation - eliminating need for external LDOs in most isolated designs.

How is dead-time programmed on the LTC3721EUF-1#PBF?

Dead-time on the LTC3721EUF-1#PBF is set by connecting a resistor between DPRG (Pin 8) and VREF (Pin 15). The nominal 2 V voltage at DPRG generates a current that linearly controls dead-time from 90 ns to 300 ns. An optional 200 kΩ resistor from DPRG to GND compensates for internal 10 µA current source, ensuring monotonic adjustment. Exceeding 350 µA into DPRG is prohibited.

Can the LTC3721EUF-1#PBF drive SiC or GaN MOSFETs directly?

Yes - the LTC3721EUF-1#PBF's 1.5 A sink / 1 A source drivers are rated for direct gate drive of low-Qg SiC and GaN devices at ≤500 kHz. Layout best practices apply: keep DRVA/DRVB traces short, use local 1 µF ceramic VCC bypass, and avoid series gate resistors unless needed for EMI control. Rise/fall times are <10 ns into 1 nF load, matching typical wide-bandgap FET requirements.

What is the purpose of the RLEB pin on the LTC3721EUF-1#PBF?

The RLEB (Pin 11) on the LTC3721EUF-1#PBF programs leading edge blanking time (40–320 ns) to suppress current-sense noise during MOSFET turn-on. A 10k–100k resistor from RLEB to GND sets the blanking window; tying RLEB to VREF disables blanking. This feature enables use of ground-referenced sense resistors and reduces filtering burden on the CS pin - critical for stable current-mode control in noisy environments.