Analog Devices Inc. LT8711EUDC#TRPBF

Overview

LT8711EUDC#TRPBF from Analog Devices is a micropower synchronous multitopology DC/DC controller supporting buck, boost, SEPIC, ZETA, and nonsynchronous buck-boost configurations with 4.5V–42V input range, 15µA Burst Mode quiescent current, 100kHz–750kHz programmable switching frequency, and dual 2A gate drivers. It enables high-efficiency power conversion in automotive battery systems, solar panel MPPT interfaces, and industrial 24V/48V supplies.

For engineers reviewing the LT8711EUDC#TRPBF datasheet, LT8711EUDC#TRPBF pinout, LT8711EUDC#TRPBF application, or LT8711EUDC#TRPBF equivalent, key selection criteria include topology flexibility via OPMODE pin, input voltage regulation capability at EN/FBIN, 100% duty cycle support in buck dropout, and validated QFN-20 (3mm × 4mm) thermal performance with θJC = 6.8°C/W.

Technical Context

The LT8711EUDC#TRPBF implements constant-frequency current-mode PWM control with dual independent gate drivers (TG: BIAS/INTVEE-rail PFET drive; BG: GND/INTVCC-rail NFET drive), slope-compensated ramp generation, and dual regulation loops-output voltage via FB (0.800V reference) and input voltage via EN/FBIN (1.200V reference). Its architecture supports automatic mode transitions between FCM, DCM, and low-noise Burst Mode based on load and SYNC pin state.

Topology selection is hardware-configured via OPMODE pin (GND = buck/ZETA; INTVCC = boost/SEPIC; 100pF-to-GND = nonsynchronous buck-boost), while reset logic monitors UVLO on VIN/EXTVCC (<4.5V), INTVCC (<3.6V), INTVEE (BIAS–INTVEE <3.6V), die temperature (>165°C), and EN/FBIN thresholds to enforce safe startup and fault recovery.

Key Specifications

Pinout & Package

LT8711EUDC#TRPBF is housed in a 20-lead 3mm × 4mm plastic QFN package with exposed thermal pad (Pin 21 = GND), optimized for low-inductance layout and efficient heat dissipation in high-current DC/DC converters.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multitopology controller applications.

Compared with LTC3789EFE#TRPBF and LM5170QQRGERQ1, the LT8711EUDC#TRPBF offers unique integration of topology selection, input voltage regulation, and ultra-low IQ in a compact QFN - making it optimal for space-constrained, battery-sensitive, and multi-source industrial systems where flexibility and standby efficiency are prioritized over raw current capacity.

Availability

LT8711EUDC#TRPBF is available at Aetrix Electronics and suitable for automotive battery management, solar MPPT interfaces, and industrial 24V/48V power distribution requiring stable component supply, extended temperature qualification, and long-term production continuity.

Supply support for LT8711EUDC#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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, communications, industrial automation, and automotive markets.

The LT8711 product line delivers highly flexible, low-quiescent-current DC/DC controllers for demanding power conversion applications where input voltage variability, topology adaptability, and standby efficiency are critical - especially in automotive, renewable energy, and portable industrial equipment.

FAQ

What topologies does the LT8711EUDC#TRPBF support, and how is topology selected?

The LT8711EUDC#TRPBF supports synchronous buck, boost, SEPIC, ZETA, and nonsynchronous buck-boost topologies. Topology is selected via the OPMODE pin: tie to GND for buck/ZETA, to INTVCC for boost/SEPIC, or to a 100pF capacitor to GND for nonsynchronous buck-boost. This hardware-based selection eliminates firmware dependency and ensures deterministic behavior at power-up. The LT8711EUDC#TRPBF's internal logic interprets the OPMODE state before enabling gate drivers, preventing misconfiguration during startup.

How does the LT8711EUDC#TRPBF achieve 15µA quiescent current, and under what conditions is it active?

The LT8711EUDC#TRPBF achieves 15µA typical quiescent current in Burst Mode operation, triggered automatically when load current drops sufficiently to cause VC voltage to fall below a threshold - disabling switching and powering down most internal circuitry except essential bias and monitoring blocks. This occurs only when EN/FBIN is above 1.03V (chip enabled) and output is in regulation. The LT8711EUDC#TRPBF maintains this ultra-low IQ while preserving fast wake-up response and low output ripple (<10mVpp), making it ideal for battery-backed systems.

What is the function of the EN/FBIN pin beyond chip enable, and how is input voltage regulation implemented?

Beyond chip enable, the EN/FBIN pin serves as the input to an error amplifier (EA2) that compares its voltage against a 1.200V internal reference. When configured with a resistor divider from VIN, EN/FBIN regulates input current to prevent source collapse - e.g., in solar panels or weak batteries. The LT8711EUDC#TRPBF adjusts commanded peak current in real time to hold EN/FBIN at 1.200V, directly controlling input power draw. This dual-loop capability (FB + EN/FBIN) is intrinsic to the LT8711EUDC#TRPBF and requires no external components beyond the divider.

Can the LT8711EUDC#TRPBF operate with input voltage below 4.5V, and what conditions allow that?

Yes, the LT8711EUDC#TRPBF can operate with VIN as low as 0V - but only when EXTVCC exceeds 4.5V, as the internal logic selects the higher of VIN or EXTVCC to power the INTVCC LDO. This dual-input architecture ensures continuous operation during automotive cold-crank (VIN dips to ~3V) if EXTVCC is supplied from a backup rail or auxiliary supply. The LT8711EUDC#TRPBF's absolute maximum ratings and startup sequencing are designed around this redundancy, with UVLO thresholds independently monitored on both inputs.

What thermal performance advantages does the LT8711EUDC#TRPBF QFN package offer compared to TSSOP?

The LT8711EUDC#TRPBF's 3mm × 4mm QFN package delivers θJC = 6.8°C/W - significantly lower than the 10°C/W of the TSSOP variant - due to its exposed thermal pad directly soldered to PCB copper. This enables higher sustained output current (e.g., 3.5A at 125°C ambient) without external heatsinking, reduces thermal stress on gate drivers, and improves long-term reliability in enclosed industrial enclosures. The LT8711EUDC#TRPBF's compact footprint also saves board area in space-constrained applications like automotive ECUs and portable medical devices.