Analog Devices Inc. LT1571EGN-1#PBF

Overview

LT1571EGN-1#PBF from Analog Devices (formerly Linear Technology) is a constant-current/constant-voltage PWM battery charger IC for Li-Ion, NiMH, and NiCd batteries. It delivers up to 1.5A DC charge current with 200kHz switching, features an internal 0.1Ω sense resistor for ±5% current accuracy, supports 4.1V/4.2V or 8.2V/8.4V preset battery voltages, and provides a FLAG output indicating near-full-charge condition at 20% of programmed current - used in compact cradle chargers and portable instrumentation.

For engineers reviewing the LT1571EGN-1#PBF datasheet, LT1571EGN-1#PBF pinout, LT1571EGN-1#PBF application, or LT1571EGN-1#PBF equivalent, key selection criteria include its 200kHz fixed-frequency buck topology, GN (28-pin narrow SSOP) package thermal performance (θ_JA = 40°C/W), 2.465V precision reference, programmable charge termination flag threshold, and compatibility with single-resistor current programming.

Technical Context

The LT1571EGN-1#PBF implements a current-mode PWM step-down (buck) architecture with integrated NPN power switch capable of 2A peak current. Its inner loop uses VC pin voltage (0.9V startup, 0.6V shutdown) to control duty cycle via slope-compensated current sensing through SENSE/BAT pins and a 0.1Ω internal sense resistor.

It employs dual-loop regulation: CA1 amplifies sensed battery current into IPROG (500µA/A), while VA compares battery voltage against a 2.465V reference to enforce constant-voltage mode. The FLAG comparator (E6) monitors IPROG relative to IVA to assert end-of-charge when current drops to ≤20% of full-scale - configurable down to 7.5% using RCAP on CAP pin.

Key Specifications

Pinout & Package

LT1571EGN-1#PBF is housed in a 28-pin narrow plastic SSOP (GN package) with four corner GND pins fused to the die attach paddle for enhanced thermal dissipation. PCB layout requires expanded copper land patterns under all GND pins and short, low-inductance connections between VCC1/VCC2.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar battery charger IC applications.

Compared with LTC4000IGN#PBF and BQ24610RGET, LT1571EGN-1#PBF offers superior thermal performance in a fixed 200kHz buck topology with factory-trimmed reference and integrated switch - making it optimal for compact, thermally constrained 1.5A Li-Ion chargers where design simplicity and reliability outweigh programmability needs.

Availability

LT1571EGN-1#PBF is available at Aetrix Electronics and suitable for Li-Ion cradle chargers, portable instrumentation power supplies, and industrial handheld terminals requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for LT1571EGN-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 acquired Linear Technology in 2017 and maintains full technical and manufacturing continuity for the LT® product line, including precision analog, power management, and battery charging ICs.

The LT1571 series belongs to Linear's dedicated battery management portfolio, designed specifically for high-efficiency, single-chip constant-current/constant-voltage charging of Li-Ion, NiMH, and NiCd batteries in space- and thermally constrained portable systems.

FAQ

What is the maximum continuous battery charge current supported by LT1571EGN-1#PBF?

The LT1571EGN-1#PBF supports up to 1.5A DC battery charge current under typical thermal conditions (T_A ≤ 60°C, 4-layer PCB with thermal pads). This is enabled by its 0.5Ω switch R_DS(on), fused-GND thermal pad, and 40°C/W θ_JA. Peak current capability is 2A, but sustained operation above 1.5A requires careful thermal design per the datasheet's junction temperature calculation.

How does LT1571EGN-1#PBF implement charge termination for Li-Ion batteries?

The LT1571EGN-1#PBF asserts the open-collector FLAG pin low when battery charge current drops to ≤20% of the programmed value - detected by comparing IPROG (scaled current sense) against IVA (voltage amplifier output) in comparator E6. A 0.1µF capacitor on CAP pin filters switching noise, and the threshold can be reduced to 7.5% using an RCAP resistor, enabling compliance with various battery manufacturer specifications.

Can LT1571EGN-1#PBF be used for NiMH or NiCd battery charging?

Yes, LT1571EGN-1#PBF supports NiMH and NiCd charging via constant-current mode with optional voltage limiting. Its 2.465V reference and VA amplifier allow overvoltage protection, and the FLAG output can signal transition to trickle charge. Unlike Li-Ion, NiMH/NiCd require external temperature or –dV/dt detection for full-charge termination - which the LT1571EGN-1#PBF does not provide internally.

What package type and thermal characteristics apply to LT1571EGN-1#PBF?

LT1571EGN-1#PBF uses the GN package: a 28-pin narrow plastic SSOP with four corner GND pins fused to the internal die attach paddle. Its thermal resistance is θ_JA = 40°C/W when mounted on a 4-layer PCB with proper thermal land patterns - significantly better than standard SSOP packages and enabling 1.5A continuous operation without external heatsinking.

Does LT1571EGN-1#PBF require external components for basic operation?

Yes, LT1571EGN-1#PBF requires external components for full functionality: a Schottky catch diode (e.g., MBRM120T3), inductor (e.g., 33µH), input/output capacitors, and a PROG resistor for current setting. However, it integrates the current sense resistor (0.1Ω), 2.465V reference, and NPN power switch - eliminating the need for external sense resistors, voltage references, or discrete switches in most designs.