Analog Devices Inc. LTC3785EUF-1#TRPBF

Overview

LTC3785EUF-1#TRPBF from Analog Devices (formerly Linear Technology) is a high-efficiency synchronous buck-boost DC/DC controller driving all-N-channel MOSFETs in single-inductor four-switch topology, supporting input and output voltages from 2.7V to 10V, programmable 100kHz–1MHz switching frequency, and up to 10A output current - ideal for Li-ion-powered handheld instruments and wireless modems requiring VIN above, below, or equal to VOUT.

For engineers reviewing the LTC3785EUF-1#TRPBF datasheet, LTC3785EUF-1#TRPBF pinout, LTC3785EUF-1#TRPBF application, or LTC3785EUF-1#TRPBF equivalent, key selection considerations include its No RSENSE™ forward/reverse current sensing, ±7.5% power good window, programmable burst mode, true output disconnect during shutdown, and 24-pin 4mm × 4mm QFN with exposed thermal pad.

Technical Context

The LTC3785EUF-1#TRPBF implements voltage-mode control with a 1.225V internal reference and error amplifier output (VC) that directly governs duty cycle across buck, buck-boost, and boost regions. Its proprietary four-switch architecture transitions continuously between modes using dual gate drivers (TG1/BG1 for buck path; TG2/BG2 for boost path), with nonoverlap timing of 100ns to prevent shoot-through.

It integrates independent forward current limit sensing (ISVIN/ISSW1) and reverse current limit sensing (ISVOUT/ISSW2), both programmable via ILSET resistor; supports CCM pin-selectable reverse conduction (–15mV threshold when low); and features a dedicated VSENSE pin for independent OV/UV monitoring with 1.5% hysteresis - decoupled from FB for optimized transient response.

Key Specifications

Pinout & Package

Package: 24-lead (4mm × 4mm) plastic QFN with exposed thermal pad (Pin 25), RoHS-compliant, lead-free finish. Exposed pad must be soldered to PCB ground for thermal and electrical performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC3785EUF#TRPBF, the LTC3785EUF-1#TRPBF adds CCM pin control for reverse current management and improves fault response granularity; versus LTC3785IGUF-1#TRPBF, it trades extended temperature rating and tighter VCC spec for lower cost in commercial-grade applications.

Availability

LTC3785EUF-1#TRPBF is available at Aetrix Electronics and suitable for handheld instruments, wireless modems, and cellular telephones requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LTC3785EUF-1#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 technical and manufacturing continuity for the LTC product line, renowned for high-performance power management ICs.

The LTC3785-1 family was designed specifically for high-efficiency, wide-input-range buck-boost conversion in portable and battery-powered systems where VIN may vary above, below, or equal to VOUT.

FAQ

What is the maximum output current supported by the LTC3785EUF-1#TRPBF?

The LTC3785EUF-1#TRPBF is a controller - not a regulator - and does not define maximum output current internally. It supports up to 10A output current when paired with appropriately rated external N-channel MOSFETs, inductor, and layout. Actual current capability depends on thermal design, MOSFET R_DS(ON), and inductor saturation rating - confirmed in typical applications with Si7940 MOSFETs and 4.7μH inductors.

Does the LTC3785EUF-1#TRPBF require external current-sense resistors?

No. The LTC3785EUF-1#TRPBF implements No RSENSE™ technology, using the R_DS(ON) of external N-channel MOSFETs for both forward and reverse current limiting. A resistor on the ILSET pin programs the sense threshold (20–155mV), eliminating power loss and board space associated with discrete sense resistors - a key feature confirmed in the datasheet's "No RSENSE is a trademark" statement and electrical characteristics table.

How does the PGOOD function work on the LTC3785EUF-1#TRPBF?

The PGOOD pin on the LTC3785EUF-1#TRPBF is an open-drain output that pulls low when the voltage on the VSENSE pin deviates more than ±7.5% from the 1.225V internal reference - indicating VOUT is out of regulation. It also asserts low during RUN/SS shutdown or input UVLO. A 15μs deglitch filter prevents false trips; the pin requires an external pull-up resistor to function correctly - verified in the Electrical Characteristics table (PGOOD Output Low = 200–500mV at 500μA sink).

Can the LTC3785EUF-1#TRPBF operate with input voltage below 2.7V?

No. The absolute minimum input voltage for the LTC3785EUF-1#TRPBF is 2.7V, as specified in the Absolute Maximum Ratings and Electrical Characteristics tables. Operation below this violates the guaranteed operating range; startup voltage is typically 2.465V but sustained operation requires ≥2.7V to maintain VCC regulation and gate drive integrity - confirmed in Figure G10 (VIN Start-Up Voltage vs Temperature) and the "Input Operating Voltage" parameter (2.7V min).

What is the purpose of the CCM pin on the LTC3785EUF-1#TRPBF?

The CCM (Continuous Conduction Mode) pin on the LTC3785EUF-1#TRPBF selects reverse current limit behavior: when pulled low (or grounded), it enables a fixed –15mV reverse threshold for minimal reverse conduction; when driven high, it sets reverse limit equal to the forward limit defined by ILSET. This allows designers to choose between true output disconnect (CCM low) or bidirectional current capability (CCM high) - explicitly documented in the PIN FUNCTIONS section and Electrical Characteristics table.