Analog Devices Inc. LT1339IN#PBF

Overview

LT1339IN#PBF from Analog Devices (formerly Linear Technology) is a high-power synchronous current-mode DC/DC controller IC designed for buck, inverting, and negative-output converters up to 60V input. It drives dual N-channel MOSFETs with adaptive nonoverlapping gate logic, supports programmable average current limiting (120 mV threshold), fixed-frequency operation up to 150 kHz, and features a 5 V reference output with 10 mA load capability - used in telecom power supplies and industrial DC/DC systems.

For engineers reviewing the LT1339IN#PBF datasheet, LT1339IN#PBF pinout, LT1339IN#PBF application, or LT1339IN#PBF equivalent, key selection criteria include its 60 V max input voltage, dual N-MOSFET synchronous drive capability, programmable average current limit, soft-start control via external capacitor, and phase-reversal support for inverting topologies.

Technical Context

The LT1339IN#PBF implements a constant-frequency current-mode control architecture with an internal oscillator programmable up to 150 kHz and synchronizable to external clocks. Its error amplifier (1.25 V reference, 2000 µmho transconductance) regulates output voltage by modulating the VC pin, which sets the current comparator threshold.

It integrates dual gate drivers with adaptive nonoverlapping logic to prevent shoot-through, supports minimum off-time protection (~1 µs), and provides separate PGND and SGND pins for noise isolation. The IAVG pin enables true average current limiting independent of duty cycle and inductor ripple, while the PHASE pin allows topology reconfiguration between buck and inverting modes.

Key Specifications

Pinout & Package

LT1339IN#PBF is housed in a 20-lead PDIP (Plastic Dual In-line Package) with 0.3-inch width and through-hole mounting. Thermal resistance θ_JA = 70°C/W. Pin 1 is SYNC; Pin 20 is VBOOST. All pins are electrically defined per Linear Technology's official pin function table.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous DC/DC controller applications.

Compared with LTC3775 and LM5116, the LT1339IN#PBF uniquely combines programmable average current limiting, topology-flexible PHASE control, and a dedicated 5 V reference - making it optimal for telecom and battery-backed systems requiring deterministic DC load current regulation and multi-topology reuse.

Availability

LT1339IN#PBF is available at Aetrix Electronics and suitable for 48V telecom power supplies, industrial DC/DC converters, and lead-acid battery backup systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LT1339IN#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.

The LT1339 product line was developed for high-power, high-voltage synchronous DC/DC controllers targeting telecom infrastructure, industrial power, and battery-backed systems demanding precision current regulation and topology flexibility.

FAQ

What is the maximum input voltage supported by the LT1339IN#PBF?

The LT1339IN#PBF supports up to 60 V on its current sense inputs (SENSE+ and SENSE–) and operates with a 12VIN supply up to 20 V. Its TS pin tolerates up to 60 V, enabling use in high-voltage buck and inverting topologies. Absolute maximum ratings specify –0.3 V to 60 V for sense inputs and –0.3 V to 75 V for VBOOST, but functional operation is validated up to 60 V input in typical applications like 48 V telecom supplies.

How does the PHASE pin affect converter topology in the LT1339IN#PBF?

The PHASE pin on the LT1339IN#PBF determines driver assignment: when floating, TG drives the high-side switch and BG the low-side switch (standard buck); when grounded, their roles reverse - enabling inverting and negative-output configurations. This single-pin reconfiguration eliminates PCB redesign for multiple topologies and is confirmed in the Applications Information section and Typical Application schematic.

Can the LT1339IN#PBF implement true average current limiting, and how is it configured?

Yes, the LT1339IN#PBF implements true average current limiting via the IAVG pin, using an external capacitor to form a single-pole integrator with its internal 50 kΩ impedance. The average limit threshold is 110–130 mV across the sense resistor - independent of duty cycle and ripple current. Shorting IAVG to SGND disables this function, as documented in the Electrical Characteristics table and Applications Information.

What is the purpose of the 5VREF pin on the LT1339IN#PBF, and what load can it drive?

The 5VREF pin on the LT1339IN#PBF provides a regulated 4.75–5.25 V output capable of sourcing up to 10 mA DC (20 mA pulsed). It powers external timing components (RCT, CCT), slope compensation networks, and local logic - eliminating need for a separate reference IC. The output is disabled during shutdown, as specified in the Electrical Characteristics table under "5V Reference Load Range."

Does the LT1339IN#PBF include protection against shoot-through in its gate drivers?

Yes, the LT1339IN#PBF incorporates adaptive nonoverlapping gate drive logic that actively monitors TG and BG outputs to enforce dead time - preventing simultaneous conduction of high- and low-side MOSFETs. This feature is implemented in hardware and does not require external timing components, as confirmed in the Features list and Operation section of the datasheet.