Analog Devices Inc. LT1370CR#TRPBF

Overview

LT1370CR#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic 500kHz current-mode switching regulator IC with integrated 6A power switch, supporting boost, buck, flyback, forward, inverting, and Cuk topologies. It delivers up to 2A output at 12V from 5V input with ≥92% efficiency, operates down to 2.7V input, and regulates both positive and negative outputs using dedicated FB and NFB pins.

For engineers reviewing the LT1370CR#TRPBF datasheet, LT1370CR#TRPBF pinout, LT1370CR#TRPBF application, or LT1370CR#TRPBF equivalent, key selection considerations include its 6A internal switch, 0.065Ω typical R_DS(on), 4.5mA quiescent current, dual-polarity feedback architecture, and synchronization capability up to 800kHz - critical for compact DC/DC designs in portable and multi-rail systems.

Technical Context

The LT1370CR#TRPBF implements peak-current-mode control with adaptive anti-saturation driver circuitry, enabling fast transient response and inherent pulse-by-pulse overcurrent protection. Its error amplifier features nonlinear transconductance (1100–1900 µmho), increasing 10× when FB exceeds V_REF by 40mV to suppress startup overshoot.

Oscillator frequency shifts 5:1 (to ~100kHz) when FB drops below 0.6V during overload, reducing stress on external components. The VC pin serves triple duty: compensation node (via RC network), soft-start control (capacitor-coupled clamp), and current-limit adjustment (voltage clamping).

Key Specifications

Pinout & Package

LT1370CR#TRPBF uses the 7-lead plastic DD (R) package with exposed tab for thermal dissipation (θ_JA = 30°C/W on 0.5 in² copper). Pin 1 is VC; Pin 2 is FB; Pin 3 is NFB; Pin 4 is S/S; Pin 5 is VIN; Pin 6 is VSW; Pin 7 is GND. The tab is internally connected to GND.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC3780EFE#PBF and TPS55340RTER, the LT1370CR#TRPBF uniquely integrates dual-polarity feedback, a 6A switch, and oscillator frequency shifting - making it the only option among the three that supports self-contained ±15V flyback conversion without auxiliary components or external controllers.

Availability

LT1370CR#TRPBF is available at Aetrix Electronics and suitable for laptop power supplies, multi-output flyback converters, inverting DC/DC supplies, and laser diode biasing requiring stable component supply and long-term production continuity.

Supply support for LT1370CR#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 acquired Linear Technology in 2017 and maintains full product support, documentation, and manufacturing continuity for legacy Linear parts including the LT1370 series.

The LT1370CR#TRPBF belongs to Linear's high-frequency current-mode switching regulator product line, designed specifically for compact, high-efficiency DC/DC conversion in portable and multi-rail industrial systems where board space and thermal management are critical constraints.

FAQ

What is the maximum output current achievable with LT1370CR#TRPBF in a boost configuration?

The LT1370CR#TRPBF supports up to 2A continuous output current at 12V from a 5V input, as verified in the TA01 typical application circuit. This is constrained by the 6A internal switch current limit, thermal limits of the R-package (θ_JA = 30°C/W), and inductor saturation. At higher loads, junction temperature rise necessitates derating or enhanced heatsinking; the datasheet specifies 1.8A max in standard layout per Figure TA02 efficiency curve.

Can LT1370CR#TRPBF regulate both positive and negative outputs simultaneously?

Yes, the LT1370CR#TRPBF can regulate both polarities simultaneously using its dedicated FB and NFB pins, as demonstrated in the Dual Output Flyback Converter (TA04). When both pins are active, the IC prevents either output from exceeding its set voltage - e.g., if the +15V rail is lightly loaded, the –15V rail regulates tightly while the +15V rail sags slightly, avoiding uncontrolled overvoltage.

What is the purpose of the VC pin on LT1370CR#TRPBF, and how is it used in practice?

On the LT1370CR#TRPBF, the VC pin serves three functions: (1) error amplifier output for loop compensation (RC network to ground), (2) soft-start node (capacitor-coupled clamp), and (3) current-limit adjustment (voltage clamping). During operation, VC sits between 1V (light load) and 1.9V (heavy load); pulling it below 0.9V forces zero duty cycle, placing the IC in idle mode - a feature used for precise current limiting and controlled startup sequencing.

Does LT1370CR#TRPBF support external clock synchronization, and what is the valid frequency range?

Yes, the LT1370CR#TRPBF supports external synchronization via its S/S pin. The guaranteed synchronization range is 600 kHz to 800 kHz, corresponding to 1.05× to 1.6× its nominal 500 kHz switching frequency. Operation above 700 kHz requires caution due to reduced internal slope compensation amplitude, which may cause subharmonic oscillation at duty cycles >50%; this is mitigated by using higher-inductance values per the datasheet guidance.

What package type and thermal characteristics apply to LT1370CR#TRPBF?

The LT1370CR#TRPBF uses the 7-lead plastic DD (R) package with exposed GND-connected tab. Its thermal resistance is θ_JA = 30°C/W when mounted on 0.5 in² copper over an internal ground plane, and θ_JC = 4°C/W. Maximum junction temperature is 125°C; derating is required above 85°C ambient unless additional heatsinking is applied. The tab must be soldered to maximize thermal performance.