Analog Devices Inc. LT1370CT7#PBF

Overview

LT1370CT7#PBF from Analog Devices (formerly Linear Technology) is a monolithic 500kHz current-mode switching regulator IC with integrated 6A power switch, capable of boost, buck, flyback, forward, inverting, and Cuk topologies. It delivers up to 2A output at 12V from 5V input, features 1.245V reference voltage, 0.065Ω typical switch R_DS(on), and operates down to 2.7V input. It is used in laptop computer supplies and dual-output flyback converters.

For engineers reviewing the LT1370CT7#PBF datasheet, LT1370CT7#PBF pinout, LT1370CT7#PBF application, or LT1370CT7#PBF equivalent, key selection considerations include its 6A internal switch, ±2.48V dual-reference architecture for positive/negative regulation, 12µA shutdown current, external synchronization capability (600–800kHz), and TO-220-7 package thermal performance (θ_JA = 50°C/W).

Technical Context

The LT1370CT7#PBF implements current-mode control with pulse-by-pulse current limiting, adaptive anti-saturation driver circuitry, and nonlinear error amplifier transconductance (1100–1900 µmho) that increases 10× above 40mV FB overdrive to suppress startup/overload overshoot. Its oscillator shifts frequency 5:1 when FB drops below 0.6V, enhancing overload protection.

It supports dual-polarity regulation via separate FB (1.245V reference) and NFB (–2.48V reference) pins, enabling independent sensing of positive and negative outputs in flyback configurations. The VC pin serves as error amplifier output, current limit control point, and soft-start node - clamped externally to adjust duty cycle or implement controlled startup.

Key Specifications

Pinout & Package

LT1370CT7#PBF uses a 7-lead TO-220 package with exposed tab (GND-connected) for thermal dissipation. θ_JA = 50°C/W, θ_JC = 4°C/W. Mounting requires thermal interface to heatsink or copper pour.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar switching regulator applications.

Compared with LTC3780EFE#PBF and LM5118MH/NOPB, the LT1370CT7#PBF provides the highest level of integration (6A switch + dual reference + sync/shutdown) in a single TO-220 package, minimizing external components and PCB area for sub-3A boost/inverting/flyback designs.

Availability

LT1370CT7#PBF is available at Aetrix Electronics and suitable for laptop computer supplies, dual-output flyback converters, inverting supplies, and Li-ion battery-powered boost regulators requiring stable component supply across production lifecycles.

Supply support for LT1370CT7#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 technical and manufacturing continuity for legacy Linear products including the LT1370 family.

The LT1370 product line was designed for high-efficiency, multi-topology DC/DC conversion in space-constrained portable and industrial systems, emphasizing integration, thermal robustness, and flexible feedback architectures.

FAQ

What is the maximum output current achievable with the LT1370CT7#PBF in a boost configuration?

The LT1370CT7#PBF supports up to 2.8 A output current at 5 V when powered from a 9 V input, as verified in the TA05 typical application circuit. This is constrained by the 6 A internal switch current limit, inductor saturation, and thermal limits of the TO-220 package (θ_JA = 50°C/W). At 12 V output from 5 V input, maximum continuous output is 1.8–2.0 A depending on layout and heatsinking. Derating is required above 70°C ambient.

Can the LT1370CT7#PBF regulate both positive and negative outputs simultaneously?

Yes, the LT1370CT7#PBF can regulate both polarities simultaneously using its dedicated FB (1.245 V reference) and NFB (–2.48 V reference) pins, as demonstrated in the "Dual Output Flyback Converter with Overvoltage Protection" application (TA04). Each output uses its own resistor divider, and the IC prevents either rail from exceeding its setpoint - critical for balanced bipolar supplies in instrumentation.

What is the purpose of the VC pin on the LT1370CT7#PBF, and how is it used in design?

The VC pin on the LT1370CT7#PBF is the error amplifier output and serves three functions: (1) frequency compensation node (RC network to ground), (2) current limit adjustment point (voltage clamp sets peak switch current), and (3) soft-start control (capacitor-coupled clamp). During operation, VC voltage ranges from ~1.0 V (light load) to ~1.9 V (heavy load), directly controlling duty cycle and switch conduction time.

Does the LT1370CT7#PBF require an external diode, and what are the key selection criteria?

Yes, the LT1370CT7#PBF requires an external Schottky output diode such as the MBRD835L (8 A, 35 V, 0.4 V VF @ 3 A). Key selection criteria include: reverse voltage rating ≥ output voltage, average forward current ≥ output current, low forward voltage to minimize loss, and fast recovery to handle 500 kHz switching. For inverting or flyback topologies, diode placement and polarity must match the specific application schematic.

How does the LT1370CT7#PBF handle overload or short-circuit conditions?

The LT1370CT7#PBF employs multiple overload protections: (1) pulse-by-pulse current limiting (6–10 A switch limit), (2) oscillator frequency shifting (5:1 reduction when FB < 0.6 V), and (3) thermal shutdown (T_J > 125°C). Unlike voltage-mode controllers, its current-mode architecture provides immediate response to input surges and output shorts. Note that boost topology lacks inherent short-circuit protection - input current is limited only by source impedance.