Analog Devices Inc. LT1512CGN#PBF

Overview

LT1512CGN#PBF from Analog Devices (formerly Linear Technology) is a 500kHz current-mode switching regulator IC optimized for SEPIC- and flyback-based constant-current/constant-voltage battery chargers. It integrates dual feedback paths (voltage via FB pin, current via IFB pin), supports input voltages as low as 2.4V, delivers up to 1A charging current for single Li-ion cells, and maintains 1% voltage accuracy in CV mode - enabling precision lithium battery charging in portable and industrial power systems.

For engineers reviewing the LT1512CGN#PBF datasheet, LT1512CGN#PBF pinout, LT1512CGN#PBF application, or LT1512CGN#PBF equivalent, this page provides verified technical context, validated pin functions, real-world charging topology constraints, thermal derating guidance, and confirmed alternative options for battery charger design.

Technical Context

The LT1512CGN#PBF implements current-mode control with a dedicated 500kHz oscillator and adaptive anti-saturation logic for rapid switch turn-off. Its dual inverting error amplifier accepts both voltage feedback (FB, referenced to 1.245V internal bandgap) and current feedback (IFB, regulated at –100mV during CC mode), enabling independent regulation of battery voltage and charge current without shared sensing paths.

It features separate ground pins (GND for switch return, GND S for control circuitry) to isolate high-di/dt switch currents from sensitive analog feedback. The VC pin serves as both compensation node and current limit control point (0–1.8A range over 1V–1.9V), while the multifunction S/S pin supports logic-level shutdown (12µA quiescent) and external synchronization (600–800kHz).

Key Specifications

Pinout & Package

LT1512CGN#PBF is housed in an 8-lead PDIP (N8) package with 0.300-inch width, rated for 0°C to 70°C ambient operation and featuring exposed leadframe for moderate thermal dissipation (θJA = 100°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC4000-1 and MAX1771, the LT1512CGN#PBF uniquely combines an integrated 1.5A switch, ground-referenced –100mV current sense, and 1% CV accuracy in a single PDIP package - making it optimal for compact, lithium-focused, cost-sensitive SEPIC charger designs where layout simplicity and safety-critical voltage precision are prioritized.

Availability

LT1512CGN#PBF is available at Aetrix Electronics and suitable for portable medical devices, industrial backup systems, cordless power tools, and automotive auxiliary battery chargers requiring stable component supply and long-term production continuity.

Supply support for LT1512CGN#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 legacy Linear parts including the LT1512 family.

The LT1512CGN#PBF belongs to Linear's precision battery charger IC product line, designed specifically for SEPIC- and flyback-based constant-current/constant-voltage charging of Li-ion, NiMH, NiCd, and lead-acid batteries in space-constrained, thermally demanding applications.

FAQ

What is the maximum battery voltage supported by the LT1512CGN#PBF in a SEPIC configuration?

The LT1512CGN#PBF itself does not impose a direct battery voltage limit. In SEPIC topology, maximum battery voltage is constrained by the switch voltage rating: VSW ≤ 40V. Since VSW = VIN + VBAT, the practical maximum VBAT is 40V – VIN. For example, with VIN = 12V, VBAT must remain ≤ 28V. This allows charging up to 30V battery stacks (e.g., 7S Li-ion) when VIN is sufficiently low - consistent with the datasheet's "Charges Any Number of Cells Up to 30V" specification.

Can the LT1512CGN#PBF be used with a flyback topology instead of SEPIC?

Yes, the LT1512CGN#PBF is explicitly designed for both SEPIC and flyback topologies. Its ground-referenced IFB pin and dual feedback architecture simplify current sensing in either configuration. However, in flyback, the transformer's auxiliary winding must provide isolated feedback for the FB pin, and the primary-side current sense resistor must be placed such that its voltage is referenced to GND S - unlike SEPIC, where the sense resistor is naturally ground-referenced. Layout and transformer design become more critical in flyback implementations.

How does the LT1512CGN#PBF achieve 1% constant-voltage accuracy despite FB pin bias current?

The LT1512CGN#PBF achieves 1% CV accuracy by specifying FB input current ≤ 600nA and recommending a 100µA divider current (e.g., R2 = 12.4kΩ with 1.245V reference). This ensures bias current error contributes < 0.6% to total voltage error. The datasheet further quantifies worst-case error from bias current variation (±0.42% with R2 = 41.2kΩ), confirming that proper resistor selection keeps total CV error within ±1% across temperature and process variation - a key requirement for lithium battery safety.

Is the LT1512CGN#PBF pin-compatible with other members of the LT1512 family?

Yes, the LT1512CGN#PBF shares identical pinout and electrical behavior with all LT1512 variants (e.g., LT1512CS8#PBF, LT1512IN8#PBF), differing only in package type (PDIP vs. SO) and temperature grade (C-grade 0°C–70°C vs. I-grade –40°C–85°C). The 'C' in LT1512CGN#PBF denotes Commercial temperature grade, 'GN' indicates Narrow 8-lead PDIP package, and '#PBF' confirms lead-free finish - all electrically and mechanically interchangeable within the same package footprint.

What thermal derating applies to the LT1512CGN#PBF at elevated ambient temperatures?

The LT1512CGN#PBF has a maximum junction temperature of 125°C and θJA = 100°C/W in the N8 PDIP package. At 70°C ambient, the allowable power dissipation is (125°C – 70°C)/100°C/W = 0.55W. With typical switch dissipation of ~0.24W at 0.5A charge current and 10V input, the remaining ~0.31W budget supports higher loads - but above 60°C ambient, charging current must be reduced to prevent exceeding TJMAX. Thermal calculations per the datasheet Application Information section are mandatory for reliable operation.