Analog Devices Inc. LTC3335EUDC#PBF

Overview

LTC3335EUDC#PBF from Analog Devices (formerly Linear Technology) is a nanopower buck-boost DC/DC converter with integrated precision coulomb counter, designed for ultra-long-life primary-cell battery systems. It delivers up to 50mA output current, operates down to 1.8V input, features 680nA quiescent current in regulation, and supports eight pin-selectable output voltages (1.8V–5.0V) - enabling precise power management in wireless sensor nodes.

For engineers reviewing the LTC3335EUDC#PBF datasheet, LTC3335EUDC#PBF pinout, LTC3335EUDC#PBF application, or LTC3335EUDC#PBF equivalent, this device is critical for low-power energy harvesting interfaces, battery discharge monitoring in IoT edge devices, and applications requiring I²C-accessible accumulated charge data with ±5% accuracy.

Technical Context

The LTC3335EUDC#PBF implements a hysteretic buck-boost topology with four internal MOSFETs (A–D) operating in H-bridge mode, enabling seamless step-up/step-down conversion across 1.8V–5.5V input while maintaining regulation at microamp loads. Its sleep/wake algorithm uses dual thresholds (sleep and wake-up) to minimize switching loss, achieving 680nA quiescent current when regulated and no load.

Coulomb counting is performed via real-time integration of inductor current during each AC(ON) cycle, with charge quantized per cycle using an internal 50-bit counter chain. The 8 MSBs are accessible via I²C, and full-scale range is programmable over 32,768:1 via prescaler M and IPEAK selection (5mA–250mA), supporting battery capacities from 1.094mA·hr to 1793A·hr.

Key Specifications

Pinout & Package

Package: 3mm × 4mm, 0.75mm height, 20-lead plastic QFN (UDC) with exposed PGND pad (Pin 21) - requires soldering to PCB ground plane for thermal and electrical performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar buck-boost with coulomb counting applications.

Compared with MAX17048G+T and BQ27441-G1A, the LTC3335EUDC#PBF uniquely combines nanopower regulation and coulomb counting in one die - eliminating external components, reducing BOM count, and enabling true single-battery operation in primary-cell IoT endpoints where <1µA system sleep current is mandatory.

Availability

LTC3335EUDC#PBF is available at Aetrix Electronics and suitable for wireless sensors, remote monitors, and Dust Networks® SmartMesh® applications requiring stable component supply and long-term lifecycle support.

Supply support for LTC3335EUDC#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; it designs high-performance analog, mixed-signal, and power management ICs for precision, reliability, and low-power applications.

The LTC3335EUDC#PBF belongs to Linear's nanopower power management product line, engineered specifically for multi-year battery operation in wireless sensing, metering, and industrial IoT endpoints.

FAQ

What is the minimum input voltage required for LTC3335EUDC#PBF to regulate output?

The LTC3335EUDC#PBF maintains regulation down to 1.8V input across all output voltage settings. Below 1.8V, the device ceases switching and enters shutdown; it resumes operation once input rises above the undervoltage lockout threshold. This 1.8V minimum enables use with partially discharged primary cells such as LiSOCl₂ or alkaline batteries in long-life deployments.

How does the LTC3335EUDC#PBF achieve 680nA quiescent current in regulation?

The LTC3335EUDC#PBF achieves 680nA quiescent current by entering a low-power sleep mode when output voltage reaches the sleep threshold. In this state, switching halts, bias currents are minimized, and only the sleep comparator remains active - drawing negligible current while continuously monitoring VOUT. Regulation resumes within 3µs when voltage drops to the wake-up threshold.

Can the coulomb counter in LTC3335EUDC#PBF be reset by software?

No, the LTC3335EUDC#PBF coulomb counter is non-resettable via I²C or any other interface. The accumulated charge register (Register C) is read-only and retains value through EN toggling or power cycles. To track partial discharge intervals, users must read the register periodically and compute deltas in firmware.

What inductor value should be used with LTC3335EUDC#PBF for a 5mA IPEAK setting?

For the 5mA IPEAK setting, the recommended inductor value is 2.2mH, as specified in Table 8 of the datasheet. This high-value inductor minimizes peak current stress on low-leakage primary cells (e.g., LiSOCl₂) and ensures stable operation at ultra-low IPEAK. Inductor DCR must be ≤11Ω to maintain efficiency and thermal performance.

Is LTC3335EUDC#PBF compatible with I²C buses operating at 1.8V logic levels?

Yes - the LTC3335EUDC#PBF supports I²C operation with DVCC as low as 1.8V. When DVCC = 1.8V, SDA and SCL input thresholds scale to 70% and 30% of DVCC respectively, ensuring compatibility with 1.8V microcontrollers. External pull-ups must connect to DVCC, not VOUT or BAT, to maintain proper logic levels.