Analog Devices Inc. LTC1436ACGN-PLL#PBF

Overview

LTC1436ACGN-PLL#PBF from Analog Devices (formerly Linear Technology) is a phase-lockable, fixed-frequency synchronous step-down switching regulator controller driving external N-channel MOSFETs. It operates from 3.5V to 36V input, delivers up to 5A output with programmable 1.19V–9V regulation, features ≤300ns minimum on-time, and integrates a 0.5A auxiliary linear regulator for low-noise CPU I/O or audio supplies - used in notebook computers and battery-powered wireless modems.

For engineers reviewing the LTC1436ACGN-PLL#PBF datasheet, LTC1436ACGN-PLL#PBF pinout, LTC1436ACGN-PLL#PBF application, or LTC1436ACGN-PLL#PBF equivalent, key selection criteria include PLL-synchronizable oscillator frequency (112–240 kHz), dual N-MOSFET synchronous drive capability, remote voltage sensing, programmable soft start, and logic-controlled micropower shutdown (I_Q < 25 µA).

Technical Context

The LTC1436ACGN-PLL#PBF implements a current-mode, constant-frequency step-down architecture with Adaptive Power™ output stage that dynamically selects between large (TGL/BG) and small (TGS) top-side MOSFET drivers to maintain fixed-frequency operation down to ~1% load. Its PLL circuit accepts external synchronization via PLLIN and adjusts oscillator frequency over 0–2.4V at PLL LPF, enabling precise timing alignment in multi-rail systems.

It integrates a secondary feedback input (SFB) to enforce continuous conduction mode regardless of auxiliary load, a built-in power-on reset timer (65536 cycles ≈ 300 ms), and a low-battery detector with LBI/LBO pins referenced to a 1.19V internal bandgap. The device supports both burst-mode (TGS open) and adaptive-power modes, with foldback current limiting optional via external configuration.

Key Specifications

Pinout & Package

Package: 24-Lead Narrow SSOP (GN), 150-mil body, RoHS-compliant, lead-free (PbF).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC1436ACGN#PBF, the LTC1436ACGN-PLL#PBF adds PLL synchronization for EMI management but requires two extra pins and external RC filtering; versus LT8610EMSE#PBF, it offers greater flexibility in high-current, multi-rail, and low-noise auxiliary supply designs at the cost of external FET complexity.

Availability

LTC1436ACGN-PLL#PBF is available at Aetrix Electronics and suitable for notebook computing, wireless modem, and portable instrumentation applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LTC1436ACGN-PLL#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.

The LTC1436A product line was designed for high-efficiency, low-noise, multi-rail DC-DC conversion in portable and battery-operated systems - emphasizing adaptive light-load behavior, precise voltage regulation, and flexible auxiliary supply integration.

FAQ

What is the primary function of the PLLIN pin on the LTC1436ACGN-PLL#PBF?

The PLLIN pin on the LTC1436ACGN-PLL#PBF accepts an external clock signal to synchronize the internal oscillator via a phase detector. When active, it locks the switching frequency and aligns the top MOSFET turn-on edge to the rising edge of the input clock, enabling deterministic timing and reduced EMI in multi-converter systems. In non-PLL applications, PLLIN must be tied to SGND.

How does the Adaptive Power™ mode operate in the LTC1436ACGN-PLL#PBF?

Adaptive Power™ mode in the LTC1436ACGN-PLL#PBF automatically switches gate drive from TGL/BG (large MOSFETs) to TGS-only (small MOSFET + Schottky diode) when load current drops below ~1% of full scale. This maintains constant-frequency operation down to light loads, avoiding efficiency collapse and audible noise associated with burst-mode switching - a key advantage over standard current-mode controllers.

Can the LTC1436ACGN-PLL#PBF generate both a main switched output and a low-noise auxiliary output simultaneously?

Yes. The LTC1436ACGN-PLL#PBF integrates control for both functions: the main synchronous buck regulates VOUT (1.19V–9V) via external N-MOSFETs, while its auxiliary block drives an external PNP transistor to deliver up to 0.5A of low-noise, low-dropout output - configurable for 12V (internal divider) or other voltages (external divider) using AUXFB and AUXON pins.

What is the purpose of the SFB pin on the LTC1436ACGN-PLL#PBF?

The SFB (Secondary Feedback) pin on the LTC1436ACGN-PLL#PBF forces continuous conduction mode regardless of main output loading. When tied to INTVCC or ground, it guarantees regulation stability for auxiliary supplies derived from transformer secondaries - ensuring consistent performance even when the main output experiences variable load transients.

Does the LTC1436ACGN-PLL#PBF support remote voltage sensing, and how is it implemented?

Yes. The LTC1436ACGN-PLL#PBF supports true remote sensing via VOSENSE and VPROG pins. VOSENSE connects directly to the load point (e.g., CPU VDD pin), while VPROG selects whether the internal error amplifier compares against the output rail or an external resistive divider - compensating for PCB trace IR drop and ensuring accurate regulation at the point-of-load.