Analog Devices Inc. LTC1730EGN-4#PBF

Overview

LTC1730EGN-4#PBF from Analog Devices (formerly Linear Technology) is a standalone 1-cell lithium-ion pulse charger IC with integrated 0.35Ω NMOS pass switch, programmable 4.1V/4.2V float voltage selection via SEL pin, C/10 end-of-charge detection, and thermal shutdown protection. It operates from 4.5V to 12V input, delivers up to 1.3A charge current (RSENSE = 0.1Ω), and draws ≤1µA in sleep mode when input is removed - ideal for handheld computers and cellular telephones requiring safe, autonomous battery charging.

For engineers reviewing the LTC1730EGN-4#PBF datasheet, LTC1730EGN-4#PBF pinout, LTC1730EGN-4#PBF application, or LTC1730EGN-4#PBF equivalent, key selection considerations include its dual-voltage float programming (4.1V/4.2V), internal overcurrent protection with 100mV sense threshold, ACPR wall-adapter-present indicator, FAULT pin for defective-battery detection, and SSOP-16 thermal design with four fused ground pads for PCB heat sinking.

Technical Context

The LTC1730EGN-4#PBF implements a constant-current/constant-voltage (CC/CV) pulse-charging algorithm using an internal charge-pump-driven NMOS switch. Its gate drive employs regulated 10µA/40µA current sources for controlled slew rates at VCC and GATE pins, minimizing inrush and EMI during switching transitions.

Charge termination relies on dual independent mechanisms: a programmable timer (t_TIMER = 3 hr × C_TIMER/0.1µF) and C/10 duty-cycle monitoring at the GATE pin. Battery temperature qualification uses an NTC thermistor network on the NTC/SHDN pin with hot/cold thresholds (2.0V/3.5V at VCC = 4V) and automatic hold-mode suspension.

Key Specifications

Pinout & Package

The LTC1730EGN-4#PBF is housed in a 16-pin narrow-body SSOP (GN) package with four corner ground pins fused to the die attach paddle for enhanced thermal conduction. Recommended PCB layout uses expanded copper lands and thermal vias connected to these pins.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar lithium-ion battery charger applications.

Compared with LTC1730ES8-4.2 and BQ24075RGTR, the LTC1730EGN-4#PBF uniquely combines hardware-programmable float voltage, autonomous NTC qualification, and three dedicated status outputs (ACPR/FAULT/CHRG) in a thermally optimized SSOP-16 package - making it optimal for MCU-less, safety-conscious portable designs.

Availability

LTC1730EGN-4#PBF is available at Aetrix Electronics and suitable for handheld computers, cellular telephones, and portable medical devices requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.

Supply support for LTC1730EGN-4#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 product support, documentation, and manufacturing continuity for all Linear ICs including the LTC portfolio.

The LTC1730EGN-4#PBF belongs to Linear's precision battery management IC family, designed specifically for autonomous, high-reliability single-cell Li-ion charging in space- and thermal-constrained portable electronics.

FAQ

What is the function of the SEL pin on the LTC1730EGN-4#PBF?

The SEL pin on the LTC1730EGN-4#PBF selects the regulated float voltage: grounding SEL sets 4.1V per cell, while connecting SEL to VCC sets 4.2V. This hardware-selectable option allows one PCB design to support two common Li-ion chemistries without firmware changes or component swaps. The threshold is specified at 0.7V, ensuring robust logic-level compatibility across operating conditions.

How does the LTC1730EGN-4#PBF detect end-of-charge?

The LTC1730EGN-4#PBF detects end-of-charge using a duty-cycle comparator that monitors the GATE pin signal. When the average on-time falls below 10% of the switching period (C/10 condition), the CHRG pin transitions from active-low to a weak 40µA pull-down state. This hardware-based method operates independently of external timing or MCU supervision, ensuring reliable termination even in standalone systems.

Can the LTC1730EGN-4#PBF operate without an external sense resistor?

Yes - the LTC1730EGN-4#PBF can operate without an external sense resistor by shorting the SENSE pin to VCC, which disables overcurrent protection. However, this configuration removes the IMAX safety limit and relies entirely on the input supply's current capability. For production designs, Linear recommends retaining R_SENSE to prevent damage from mismatched or unregulated adapters, as specified in the absolute maximum ratings.

What thermal management is required for the LTC1730EGN-4#PBF in continuous 1A charging?

For continuous 1A charging, the LTC1730EGN-4#PBF requires PCB thermal design using all four fused GND pins (1,8,9,16) connected to ≥2500mm² copper area with thermal vias to inner/ground layers. With θ_JA ≈ 90°C/W and 0.354W dissipation (1A² × 0.35Ω), junction temperature rise is ~32°C above ambient - keeping TJ well below 125°C at 75°C ambient. No heatsink is needed if layout guidelines are followed.

What happens when the NTC/SHDN pin voltage goes outside its operational range?

When the NTC/SHDN pin voltage falls below 2.0V (hot threshold) or rises above 3.5V (cold threshold) at VCC = 4V, the LTC1730EGN-4#PBF enters hold mode: charging suspends, the internal timer freezes, and the FAULT pin pulls low. The CHRG pin retains its prior state (e.g., remains active-low if charging was in progress). Charging resumes automatically once the pin voltage returns to the 2.0V–3.5V window, with no reset required.