Analog Devices Inc. LT1511ISW#PBF

Overview

LT1511ISW#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 three independent control loops (battery current, battery voltage, adapter input current). It enables simultaneous system operation and charging in portable computing equipment.

For engineers reviewing the LT1511ISW#PBF datasheet, LT1511ISW#PBF pinout, LT1511ISW#PBF application, or LT1511ISW#PBF equivalent, key selection considerations include its 3A DC charging capability, 24-pin SO Wide package with fused ground paddle, programmable charging current via PROG pin, adapter current limiting function (CLP/CLN), and industrial temperature range (–40°C to 125°C junction).

Technical Context

The LT1511ISW#PBF implements a current-mode PWM buck topology with dual feedback loops: CA1 amplifier senses battery current across RS1 and converts it to IPROG at the PROG pin; VA amplifier compares battery voltage against a 2.465V reference to regulate constant-voltage mode. A third loop (CL1) monitors adapter current via CLP/CLN to dynamically reduce charging current and prevent adapter overload.

Its internal architecture includes a 200kHz oscillator, slope compensation, BOOST-driven NPN switch with 0.25Ω typical ON resistance, soft-start controlled by VC pin capacitor, and undervoltage lockout with 6.7V rising threshold on UV pin. All GND pins (1,4,5,7,16,23,24) are internally fused to the die attach paddle for thermal conduction.

Key Specifications

Pinout & Package

LT1511ISW#PBF uses a 24-lead plastic SO Wide (SW) package with exposed thermal paddle. All seven GND pins (1,4,5,7,16,23,24) are fused internally to the die attach paddle and must be connected to an expanded PCB copper land for heat sinking (θJA = 30°C/W with internal ground plane).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT3652IMSE#PBF and BQ24610RGTT, the LT1511ISW#PBF uniquely delivers analog adapter current limiting, ground-referenced current sensing, and NPN-switch efficiency at 3A-making it optimal for cost-sensitive, thermally constrained portable systems sharing a single AC adapter.

Availability

LT1511ISW#PBF is available at Aetrix Electronics and suitable for portable computing, medical instrumentation, industrial handheld terminals, and lithium-ion power bank designs requiring stable component supply and long-term manufacturability.

Supply support for LT1511ISW#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 all Linear battery charger ICs.

The LT1511 product line was designed specifically for high-efficiency, analog-controlled battery charging in space-constrained portable electronics-emphasizing thermal robustness, adapter coexistence, and precision CV regulation for Li-Ion cells.

FAQ

What is the maximum continuous charging current supported by the LT1511ISW#PBF?

The LT1511ISW#PBF supports up to 3A DC charging current with 4A peak switch capability. This rating is validated under industrial temperature conditions (–40°C to 125°C junction) with proper PCB thermal design-specifically, connection of all GND pins to an expanded copper land per the datasheet's θJA = 30°C/W requirement. Derating applies above 85°C ambient.

How does the LT1511ISW#PBF implement adapter current limiting without microcontroller intervention?

The LT1511ISW#PBF uses dedicated CLP and CLN pins to monitor voltage across an external sense resistor (RS4). When the differential exceeds 100mV, the internal CL1 amplifier overrides the programmed charging current in real time-reducing IBAT analogically to maintain adapter current within limits. No firmware, ADC, or digital loop is required.

Can the LT1511ISW#PBF charge batteries with negative-terminal grounding?

Yes-the LT1511ISW#PBF supports ground-referenced current sensing via SENSE and BAT pins, allowing direct connection of the battery's negative terminal to system ground. This eliminates the need for high-side current sense circuitry or isolated amplifiers, simplifying layout and reducing BOM count.

What is the purpose of the BOOST pin on the LT1511ISW#PBF, and what voltage levels must be observed?

The BOOST pin on the LT1511ISW#PBF drives the base of the internal NPN switch to ensure deep saturation and low conduction loss. During switch ON, VBOOST ≈ VCC + VBAT. Absolute maximum ratings specify VBOOST ≤ 57V relative to GND and ≤ 30V relative to SW pin-exceeding these risks permanent damage to the internal transistor.

Does the LT1511ISW#PBF require external components for Li-Ion constant-voltage termination?

No-Li-Ion CV termination is fully autonomous. The LT1511ISW#PBF uses its internal 2.465V reference and OVP amplifier to detect battery voltage reaching the float threshold (set by R3/R4 divider), then smoothly transitions from constant-current to constant-voltage mode and tapers current to zero without external timers or comparators.