Analog Devices Inc. LT1766IGN-5#PBF

Overview

LT1766IGN-5#PBF from Analog Devices (formerly Linear Technology) is a fixed 5V, 200kHz monolithic buck switching regulator with 1.5A peak switch current, 5.5V–60V input range, and integrated 0.2Ω NPN power switch. It delivers high efficiency in industrial power supplies and battery-charged systems requiring stable 5V output under wide-input-voltage transients.

For engineers reviewing the LT1766IGN-5#PBF datasheet, LT1766IGN-5#PBF pinout, LT1766IGN-5#PBF application, or LT1766IGN-5#PBF equivalent, key selection criteria include its fixed 5V output, thermally enhanced SSOP package with exposed GND pad, shutdown threshold at 0.4V/2.38V, and synchronization capability from 228kHz to 700kHz.

Technical Context

The LT1766IGN-5#PBF implements current-mode control with cycle-by-cycle current limiting and patented duty-cycle-independent peak switch current maintenance. Its internal 2.9V bias regulator draws power from VIN or optionally from the BIAS pin when connected to VOUT ≥ 3V, enabling efficiency optimization at high VIN-to-VOUT ratios.

Switch saturation is achieved via external BOOST capacitor and diode, delivering 0.2Ω on-resistance at 1.5A. The device features dual SHDN thresholds (0.4V for micropower shutdown, 2.38V for UVLO), FB/SENSE pin direct connection to 5V output, and frequency foldback below 0.8V SENSE voltage to limit power dissipation during short-circuit events.

Key Specifications

Pinout & Package

LT1766IGN-5#PBF uses a 16-lead plastic SSOP package with fused leads and an exposed GND pad (Pin 17) that must be soldered to PCB ground for thermal and electrical integrity. θ_JA = 85°C/W, θ_JC (Pin 8) = 25°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar buck regulator applications.

Compared with LTC3631EMSE-5#PBF and LM5164QDDARQ1, LT1766IGN-5#PBF uniquely combines 60V input tolerance, 1.5A peak current, dual-threshold shutdown, and external synchronization in a thermally robust SSOP package - making it optimal for industrial and high-reliability non-automotive 5V buck applications demanding wide VIN and proven ruggedness.

Availability

LT1766IGN-5#PBF is available at Aetrix Electronics and suitable for industrial power supplies, battery charger control circuits, and automotive body control modules requiring stable component supply with guaranteed –40°C to 125°C operation.

Supply support for LT1766IGN-5#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 LT1766 family.

The LT1766 series was designed as a high-voltage, current-mode monolithic buck regulator targeting industrial, transportation, and distributed power applications where input voltage extremes and thermal reliability are critical.

FAQ

What is the maximum input voltage rating for the LT1766IGN-5#PBF?

The LT1766IGN-5#PBF has an absolute maximum input voltage (VIN) rating of 60V, with guaranteed operation from 5.5V to 60V across its full –40°C to 125°C junction temperature range. This makes LT1766IGN-5#PBF suitable for 48V industrial systems and automotive applications experiencing load dump transients. Exceeding 60V risks permanent damage per Absolute Maximum Ratings.

Does the LT1766IGN-5#PBF require an external feedback resistor network?

No. The LT1766IGN-5#PBF is the fixed 5V output variant - its internal resistor divider connects the SENSE (FB) pin directly to the regulated 5V output, eliminating external resistors. In contrast, the adjustable LT1766IGN#PBF requires two external resistors to set VOUT. Using LT1766IGN-5#PBF simplifies layout and improves accuracy by removing resistor tolerance and bias current errors.

How does the BOOST pin function in the LT1766IGN-5#PBF circuit?

The BOOST pin on the LT1766IGN-5#PBF drives an external capacitor-diode charge pump to generate a voltage ~5V above VIN, which saturates the internal NPN power switch and achieves 0.2Ω on-resistance. Without BOOST, switch losses would rise significantly. A typical implementation uses a 100V ceramic capacitor and Schottky diode (e.g., 1N4148W or BAT54). LT1766IGN-5#PBF requires this BOOST network for rated 1.5A performance.

What are the two shutdown thresholds on the SHDN pin of the LT1766IGN-5#PBF?

The SHDN pin of the LT1766IGN-5#PBF has two distinct thresholds: 2.38V (undervoltage lockout enable) and 0.4V (deep micropower shutdown). At 2.38V, switching begins; below 0.4V, supply current drops to 25μA max. Between thresholds, the part remains enabled but may exhibit unstable behavior. LT1766IGN-5#PBF supports open-circuit SHDN (enabled by internal bias) or logic-level control with clean 0/5V signals.

Can the LT1766IGN-5#PBF be synchronized to an external clock?

Yes. The LT1766IGN-5#PBF SYNC pin accepts logic-level inputs (10%–90% duty cycle) and synchronizes its internal 200kHz oscillator from 228kHz up to 700kHz. This feature reduces EMI by eliminating beat frequencies in multi-regulator systems. No external components are needed beyond the clock source; SYNC is directly compatible with CMOS/TTL outputs. For designs requiring strict timing alignment, LT1766IGN-5#PBF provides deterministic phase relationship to the external clock.