Analog Devices Inc. LTC4120EUD-4.2#PBF

Overview

LTC4120EUD-4.2#PBF from Analog Devices is a fixed 4.2V float voltage wireless power receiver and synchronous buck battery charger IC for Li-Ion/Polymer batteries, delivering up to 400mA charge current with ±1% feedback voltage accuracy, Dynamic Harmonization Control (DHC) for air-gap–robust resonant coupling, and integrated NTC temperature qualification - deployed in sealed medical sensors and industrial IoT nodes.

For engineers reviewing the LTC4120EUD-4.2#PBF datasheet, LTC4120EUD-4.2#PBF pinout, LTC4120EUD-4.2#PBF application, or LTC4120EUD-4.2#PBF equivalent, key selection considerations include its fixed 4.2V float voltage (vs. programmable variants), 16-pin 3mm × 3mm QFN package with exposed thermal pad, DHC input regulation at 14V, and absence of FB/FBG pins due to internal voltage reference.

Technical Context

The LTC4120EUD-4.2#PBF implements a synchronous buck topology with integrated high-side and low-side MOSFETs (R_DS(ON) = 0.8Ω / 0.5Ω), switching at 750kHz or 1.5MHz via FREQ pin selection, and uses BATSNS (Pin 10) - not FB - to directly sense battery voltage against a factory-trimmed 4.2V reference (±0.039V initial accuracy). Its DHC pin modulates receiver tank resonance by dynamically adjusting impedance when input voltage falls below 14V, enabling stable power transfer across variable coil spacing (up to 11mm demonstrated).

Unlike the programmable LTC4120, this variant replaces FB/FBG pins with BATSNS and omits external voltage divider support; it integrates low-battery preconditioning (2.21V threshold), trickle-charge mode (6–16mA), safety timer (1.3–2.8 hours), and auto-recharge triggered by 2.2% V_BAT drop - all without microprocessor intervention.

Key Specifications

Pinout & Package

Package: 16-lead (3mm × 3mm × 0.75mm) plastic QFN with exposed thermal pad (Pin 17 = GND), rated for –40°C to 125°C junction temperature. Exposed pad must be soldered to PCB ground plane for thermal and electrical integrity (θ_JA = 54°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar wireless battery charging applications.

Compared with LTC4120EUD#PBF, the LTC4120EUD-4.2#PBF trades voltage programmability for tighter 4.2V accuracy and reduced component count, while LTC4125IDDB#PBF serves a complementary transmitter role - neither is a drop-in replacement, but all three form a validated wireless charging subsystem.

Availability

LTC4120EUD-4.2#PBF is available at Aetrix Electronics and suitable for implantable medical sensors, industrial rotating equipment monitors, and sanitary food processing sensors requiring stable component supply with guaranteed long-term availability and traceable sourcing.

Supply support for LTC4120EUD-4.2#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, industrial automation, and medical electronics markets since 1965.

The LTC4120 product line delivers contactless battery charging solutions for harsh, sealed, or rotating environments - designed specifically to replace failure-prone connectors and enable maintenance-free operation in mission-critical systems.

FAQ

What is the primary function of the LTC4120EUD-4.2#PBF?

The LTC4120EUD-4.2#PBF is a wireless power receiver and synchronous buck battery charger IC optimized for Li-Ion/Polymer batteries. It delivers constant-current/constant-voltage charging up to 400mA with a factory-trimmed 4.2V float voltage, Dynamic Harmonization Control for robust air-gap operation, and integrated safety features including NTC temperature qualification and safety timer termination - all without requiring a microcontroller.

How does the DHC pin on the LTC4120EUD-4.2#PBF improve wireless charging performance?

The DHC pin on the LTC4120EUD-4.2#PBF regulates input voltage by sinking 330mARMS to dynamically tune the receiver tank's resonant frequency when input voltage drops below 14V. This maintains stable power transfer across variable coupling conditions - such as coil misalignment or distance changes up to 11mm - improving efficiency consistency and eliminating the need for manual tuning in deployed systems.

Can the LTC4120EUD-4.2#PBF be used with battery chemistries other than Li-Ion?

No - the LTC4120EUD-4.2#PBF is specifically configured for Li-Ion/Polymer batteries with a fixed 4.2V float voltage and associated charge profile (preconditioning at 2.21V, trickle charge, CC/CV transition). For other chemistries like LiFePO₄ (3.6V) or NiMH, the programmable LTC4120EUD#PBF - which supports 3.5–11V float voltage via FB/FBG - must be used instead.

What is the purpose of the BATSNS pin on the LTC4120EUD-4.2#PBF?

The BATSNS pin on the LTC4120EUD-4.2#PBF replaces the FB/FBG pins found on the programmable LTC4120 variant. It provides direct sensing of battery voltage against the internal 4.2V reference, eliminating external resistor dividers and their associated tolerance, drift, and layout sensitivity - resulting in higher accuracy, lower BOM count, and improved reliability in space-constrained designs.

Does the LTC4120EUD-4.2#PBF require external MOSFETs for operation?

No - the LTC4120EUD-4.2#PBF integrates synchronous high-side and low-side MOSFETs (R_DS(ON) = 0.8Ω / 0.5Ω) within the 3mm × 3mm QFN package. Only external passive components are required: input/output capacitors, power inductor, PROG resistor, NTC bias network, and DHC capacitor/diode - making it a complete, compact wireless charging solution.