Analog Devices Inc. LTC3770EUH#TRPBF

Overview

LTC3770EUH#TRPBF from Analog Devices (formerly Linear Technology) is a synchronous step-down switching regulator controller with valley current mode control, output voltage tracking, programmable margining, and PLL-based external clock synchronization. It operates from 4V to 32V input, delivers 0.6V–32V output (with duty cycle up to 90%), achieves ≤100ns minimum on-time, and supports resistor-programmable switching frequency - used in high-accuracy server CPU core power supplies.

For engineers reviewing the LTC3770EUH#TRPBF datasheet, LTC3770EUH#TRPBF pinout, LTC3770EUH#TRPBF application, or LTC3770EUH#TRPBF equivalent, key selection criteria include its no-R_SENSE capability via MOSFET R_DS(ON) sensing, ±0.67% 0.6V reference accuracy, programmable current limit foldback, and dual N-channel gate driver with <2.5Ω pull-up/down resistance.

Technical Context

The LTC3770EUH#TRPBF implements constant-on-time valley current mode control without requiring an external sense resistor - using either a discrete shunt or the bottom MOSFET's R_DS(ON) for current sensing. Its ITH pin serves as both error amplifier compensation node and current threshold control point (0–2.4V range), while VRNG sets nominal sense voltage from 50mV to 200mV.

Phase-locked loop synchronization accepts external clocks via PLLIN (50kΩ internal termination), with PLLFLTR pin hosting the loop filter. The controller features adjustable soft-start via TRACK/SS pin (1.4μA internal charging current), true current foldback protection (disabled at startup), and independent overvoltage/undervoltage fault detection with PGOOD open-drain output.

Key Specifications

Pinout & Package

Package: 32-lead (5mm × 5mm) plastic QFN with exposed pad (SGND, must be soldered). Thermal resistance θ_JA = 34°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous step-down controller applications.

Compared with ISL6269CRZ-T and TPS546D24RQFT, the LTC3770EUH#TRPBF uniquely combines no-R_SENSE valley current mode, ±0.67% reference, full analog tracking/margining, and PLL sync - making it optimal for high-accuracy, multi-rail server and test-system power supplies where flexibility and precision are critical.

Availability

LTC3770EUH#TRPBF is available at Aetrix Electronics and suitable for server power supply design, FPGA power sequencing, and industrial PLC power modules requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LTC3770EUH#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) is a global leader in high-performance analog, mixed-signal, and power management ICs, serving aerospace, industrial, automotive, and communications markets.

The LTC3770EUH#TRPBF belongs to Linear's high-accuracy DC/DC controller product line, designed specifically for demanding server, ASIC, and memory power applications requiring precision regulation, sequencing, and fault resilience.

FAQ

What is the minimum on-time specification for the LTC3770EUH#TRPBF, and why does it matter?

The LTC3770EUH#TRPBF has a guaranteed minimum on-time of ≤100ns. This enables stable high-frequency operation (e.g., 500kHz+) even when stepping down from high input voltages like 24V to sub-1V outputs such as 0.85V - avoiding pulse-skipping and maintaining regulation accuracy in server and CPU core supplies. The LTC3770EUH#TRPBF achieves this via its constant-on-time valley current mode architecture with precision one-shot timing.

Can the LTC3770EUH#TRPBF operate without an external current sense resistor?

Yes. The LTC3770EUH#TRPBF supports no-R_SENSE operation by using the bottom MOSFET's R_DS(ON) as the current sensing element - connecting SENSE+ to SW and SENSE– to PGND. This reduces conduction losses and PCB area. The VRNG pin configures the effective sense voltage range (50–200mV nominal), and the LTC3770EUH#TRPBF's current comparator adapts accordingly.

How does the TRACK/SS pin function in master-slave configurations?

In master-slave setups, the TRACK/SS pin on the LTC3770EUH#TRPBF accepts a voltage ramp from the master regulator's feedback node (via resistor divider), replicating its output trajectory. Internally, a 1.4μA current charges an external capacitor to generate soft-start ramps. This ensures coordinated power-up sequencing across multiple rails - critical for FPGAs and multi-core processors. The LTC3770EUH#TRPBF maintains this behavior regardless of whether configured as master or slave.

What protection features does the LTC3770EUH#TRPBF provide during fault conditions?

The LTC3770EUH#TRPBF integrates output overvoltage protection (OVP), input undervoltage lockout (UVLO), cycle-by-cycle current limiting, and current foldback during short-circuit events. OVP forces immediate top-FET turn-off and bottom-FET turn-on; UVLO disables regulation below ~3.2V; foldback reduces valley current limit to 10% of maximum when VFB drops near zero - all without external components. These protections are active in the LTC3770EUH#TRPBF by default and require no configuration.

Is the LTC3770EUH#TRPBF pin-compatible with other packages in the LTC3770 family?

No. The LTC3770EUH#TRPBF uses a 32-lead 5mm × 5mm QFN package with dedicated SENSE+ and SENSE– pins, whereas the SSOP variant (e.g., LTC3770EG#TRPBF) bonds those pins internally to SW and PGND. Pin functions differ significantly - for example, DRVCC is a separate pin in the UH package but co-bonded to INTVCC in the G package. Migration requires PCB redesign; the LTC3770EUH#TRPBF is not a drop-in replacement for SSOP versions.