Analog Devices Inc. LTC4000IUFD-1#PBF

Overview

LTC4000IUFD-1#PBF from Analog Devices is a high-voltage, high-performance battery charge controller with input voltage regulation and maximum power point tracking (MPPT) for solar panel inputs. It supports 3V–60V input and output ranges, delivers ±0.25% accurate programmable float voltage, enables instant-on operation via PowerPath™ control, and is used in solar-powered LiFePO₄ battery chargers requiring >98% MPPT efficiency.

For engineers reviewing the LTC4000IUFD-1#PBF datasheet, LTC4000IUFD-1#PBF pinout, LTC4000IUFD-1#PBF application, or LTC4000IUFD-1#PBF equivalent, key selection criteria include input voltage regulation loop (vs. current regulation), 28-lead 4mm × 5mm QFN package, ±1% programmable charge current accuracy, NTC-based temperature qualification, and compatibility with external DC/DC converters for full-featured charging systems.

Technical Context

The LTC4000IUFD-1#PBF implements an input voltage regulation loop-distinct from the LTC4000's input current regulation-enabling stable MPPT under varying solar irradiance. Its dual ideal diode architecture uses external PFETs for low-loss reverse blocking at the input (IID/CSP path) and battery-backed PowerPath™ switching (BAT/CSN path), supporting instant-on during deep discharge recovery.

It integrates four independent regulation loops: input voltage (IFB feedback to 1.000 V), battery float voltage (BFB to 1.136 V), output voltage (OFB to 1.193 V), and charge current (IBMON scaling at 20× sense voltage). All loops drive the ITH pin to coordinate external converter control, with precision current sensing enabling ≤50 mV sense voltage compliance.

Key Specifications

Pinout & Package

The LTC4000IUFD-1#PBF is housed in a 28-lead, 4 mm × 5 mm plastic QFN package (UFD) with exposed thermal pad (Pin 29 = GND). Pin functions are electrically identical to the SSOP variant but mapped to a compact footprint optimized for high-density PCB layouts and thermal performance (θ_JA = 43°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage battery charge controller applications.

Compared with LTC4000EUFD-1#PBF and LTC4000IGN-1#PBF, the LTC4000IUFD-1#PBF uniquely combines industrial temperature qualification with thermally optimized QFN packaging-enabling higher sustained charge currents in compact, harsh-environment systems without thermal throttling.

Availability

LTC4000IUFD-1#PBF is available at Aetrix Electronics and suitable for solar-powered battery charger systems, industrial backup power modules, and military portable equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LTC4000IUFD-1#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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and aerospace markets.

The LTC4000-1 product line was designed to enable flexible, high-efficiency battery charging from high-impedance sources-including solar panels, fuel cells, and wind turbines-by integrating MPPT, PowerPath™, and precision regulation in a single controller.

FAQ

What is the key functional difference between LTC4000IUFD-1#PBF and the base LTC4000?

The LTC4000IUFD-1#PBF features an input voltage regulation loop, whereas the standard LTC4000 uses an input current regulation loop. This distinction makes the LTC4000IUFD-1#PBF specifically optimized for maximum power point tracking (MPPT) from solar panels and other high-impedance sources where maintaining a fixed input voltage yields higher energy harvest. The LTC4000IUFD-1#PBF also includes updated internal thresholds and timing behavior aligned with Rev B silicon.

How does the instant-on feature work in LTC4000IUFD-1#PBF, and what triggers it?

The instant-on feature in LTC4000IUFD-1#PBF activates when the voltage on the OFB pin falls below 86% of the programmed battery float voltage (e.g., ~0.974 V for a 1.136 V BFB reference). In this state, the BGATE pin is regulated-not fully driven-to maintain OFB at that threshold, delivering immediate output voltage to downstream loads even when the battery is deeply discharged or shorted. This occurs automatically during initial power-up or recovery from fault conditions.

Can LTC4000IUFD-1#PBF be used with lithium-ion batteries, and what limitations apply?

Yes, LTC4000IUFD-1#PBF supports lithium-ion batteries via its NTC input for temperature-qualified charging, but only when configured for Li-ion-specific thresholds (e.g., cold/hot thresholds per JEITA). However, the datasheet explicitly states NTC functionality "supports Li-Ion batteries only"-meaning LiFePO₄ use requires disabling NTC or verifying external thermistor calibration against LiFePO₄ thermal profiles. Float voltage must also be reprogrammed via BFB divider to match Li-ion's 4.2 V/cell.

What external components are mandatory to configure basic charging with LTC4000IUFD-1#PBF?

Four external components are mandatory: (1) a resistor divider from BAT to FBG to set float voltage via BFB; (2) a resistor from CL to GND to program charge current limit; (3) an external PFET with gate driven by BGATE for battery PowerPath™; and (4) a second external PFET with gate driven by IGATE for input ideal diode function. Optional but recommended: capacitor on BIAS (≥470 nF), timer capacitor on TMR, and NTC/resistor network on NTC.

Does LTC4000IUFD-1#PBF require an external DC/DC converter, and how is it interfaced?

Yes, LTC4000IUFD-1#PBF is a controller-not a complete charger-and requires an external DC/DC converter (e.g., buck, boost, or buck-boost) to generate charging voltage/current. It interfaces via the ITH pin, which sinks current to regulate the converter's control node, and the CC pin, which connects an R-C compensation network to ITH. The converter's output connects to CSP/CSN, while LTC4000IUFD-1#PBF monitors and regulates its behavior through feedback loops on IFB, BFB, OFB, and IBMON.