Analog Devices Inc. LT1511CSW#PBF

Overview

LT1511CSW#PBF from Analog Devices (formerly Linear Technology) is a constant-current/constant-voltage 3A switching battery charger IC for Li-Ion, NiMH, and NiCd batteries. It integrates a 4A peak internal NPN switch, 200kHz current-mode PWM control, 0.5% reference voltage accuracy, and dual-loop regulation for both battery current and adapter input current. It enables simultaneous system operation and fast charging in portable computing and medical devices.

For engineers reviewing the LT1511CSW#PBF datasheet, LT1511CSW#PBF pinout, LT1511CSW#PBF application, or LT1511CSW#PBF equivalent, key selection criteria include its 3A DC charging capability, 8V–28V VCC input range, ground-referenced current sensing, adapter current limiting loop, and thermal performance in the 24-lead SO Wide package.

Technical Context

The LT1511CSW#PBF implements a current-mode PWM buck topology with three independent control loops: battery current (via PROG/SENSE/BAT pins), battery voltage (via OVP amplifier and 2.465V reference), and adapter input current (via CLP/CLN pins). Its internal NPN switch operates with 0.15Ω typical ON resistance and supports up to 4A peak current at 200kHz switching frequency.

It features adaptive soft-start via the VC pin (0.33µF capacitor), undervoltage lockout with 6.7V rising threshold on UV pin, and automatic sleep mode drawing only 3µA when VCC is removed. All GND pins are fused to an internal die attach paddle for thermal conduction, requiring connection to expanded PCB copper for θJA = 30°C/W.

Key Specifications

Pinout & Package

LT1511CSW#PBF is housed in a 24-lead plastic SO Wide (SW) package with exposed die attach paddle for thermal management. All seven GND pins (1, 4, 5, 7, 16, 23, 24) must be connected to a large copper area for heat dissipation. VCC pins (20, 21, 22) must be shorted together near the package.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC4000-1 and BQ24610RGTR, the LT1511CSW#PBF delivers best-in-class 0.5% reference accuracy and proven 3A thermal performance in SO Wide, making it optimal for medical and industrial applications demanding long-term CV stability and reliability under sustained load.

Availability

LT1511CSW#PBF is available at Aetrix Electronics and suitable for portable medical devices, industrial handheld terminals, laptop docking stations, and test & measurement equipment requiring stable component supply and long-term lifecycle support.

Supply support for LT1511CSW#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 legacy Linear products including the LT1511 family.

The LT1511CSW#PBF belongs to Linear's high-accuracy battery charger IC product line, designed specifically for applications requiring simultaneous system operation and fast, thermally robust charging of Li-Ion, NiMH, and NiCd batteries.

FAQ

What is the maximum continuous charging current supported by the LT1511CSW#PBF?

The LT1511CSW#PBF supports up to 3A continuous DC charging current with ±5% accuracy. This is achieved using external resistors (RS1, RPROG) and is thermally sustainable in the SO Wide package when PCB copper area meets θJA = 30°C/W requirements. Peak switch current reaches 4A during transient conditions.

Does the LT1511CSW#PBF require an external blocking diode between the IC and battery?

No, the LT1511CSW#PBF does not require an external blocking diode. When the wall adapter is unplugged, the IC enters sleep mode and draws only 3µA from the battery. The internal architecture prevents reverse current flow, eliminating the need for a series diode and its associated voltage drop and power loss.

How is battery voltage sensing implemented on the LT1511CSW#PBF?

The LT1511CSW#PBF uses a precision resistive divider (R3/R4) connected between VBAT and GND, feeding the OVP pin. With a 2.465V internal reference, this sets the constant-voltage termination point-for example, 8.4V for two-series Li-Ion cells. The OVP pin draws only 3nA, enabling use of high-value, low-power resistors (e.g., 162kΩ and 390kΩ).

Can the LT1511CSW#PBF regulate input adapter current while charging?

Yes, the LT1511CSW#PBF includes a dedicated adapter current limiting loop using CLP and CLN pins. By sensing voltage across an external resistor (RS4), it dynamically reduces battery charging current to keep total adapter load within a preset limit-enabling safe concurrent system operation and charging without adapter overload.

What thermal design considerations apply to the LT1511CSW#PBF in high-current operation?

The LT1511CSW#PBF requires connection of all seven GND pins and the exposed die attach paddle to a large, low-thermal-resistance PCB copper area. With proper layout, θJA = 30°C/W is achievable, allowing full 3A operation at ambient temperatures up to 60°C. Derating curves in the datasheet show maximum current vs. ambient temperature and PCB copper area.