Analog Devices Inc. LTC1436AIGN-PLL#PBF

Overview

LTC1436AIGN-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, maintains constant frequency down to ~1% load via Adaptive Power™ mode, and integrates a 0.5A auxiliary linear regulator for low-noise CPU I/O or audio supplies - used in notebook computers and battery-powered instrumentation.

For engineers reviewing the LTC1436AIGN-PLL#PBF datasheet, LTC1436AIGN-PLL#PBF pinout, LTC1436AIGN-PLL#PBF application, or LTC1436AIGN-PLL#PBF equivalent, key selection criteria include PLL-synchronizable oscillator (112–240 kHz), ≤300 ns minimum on-time, dual N-MOSFET synchronous drive, remote sense capability, and 24-lead narrow SSOP package with verified thermal resistance (θ_JA = 110°C/W).

Technical Context

The LTC1436AIGN-PLL#PBF implements a current-mode, constant-frequency control architecture with an internal 1.19V reference and error amplifier (EA) whose output (ITH pin) modulates peak inductor current. Its Adaptive Power™ stage dynamically routes gate drive to either large (TGL/BG) or small (TGS) external N-MOSFETs based on load, enabling continuous-frequency operation down to ~50 mA while avoiding gate-charge losses typical of Burst Mode.

Phase-locked loop functionality is enabled via PLLIN and PLL LPF pins: PLLIN accepts external sync signals (50 kΩ internal termination to SGND), and PLL LPF serves as both phase detector output and oscillator control voltage (0–2.4 V range), shifting f_OSC ±30% around nominal 125 kHz (C_OSC = 100 pF). The SFB pin forces continuous conduction when tied to ground, ensuring regulation under secondary-winding feedback conditions.

Key Specifications

Pinout & Package

Package: 24-lead narrow plastic SSOP (GN), 150-mil body width, θ_JA = 110°C/W. Pin 1 marked by notch or dot; exposed pad not electrically connected.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous step-down controller applications.

Compared with LTC1436ACGN-PLL#PBF, the LTC1436AIGN-PLL#PBF offers guaranteed –40°C to 85°C operation and higher thermal reliability; versus MP2451DT-LF-Z, it provides scalable current handling (via external FETs), PLL synchronization, and integrated auxiliary regulation - critical for precision instrumentation and multi-rail embedded systems.

Availability

LTC1436AIGN-PLL#PBF is available at Aetrix Electronics and suitable for notebook computers, portable instrumentation, and industrial DC power distribution systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LTC1436AIGN-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 acquired Linear Technology in 2017 and maintains its high-performance power management portfolio with rigorous automotive and industrial qualification standards.

The LTC1436A series belongs to Linear's precision synchronous buck controller product line, designed specifically for high-efficiency, low-noise, multi-rail power systems in portable and instrumentation applications where thermal robustness and EMI control are critical.

FAQ

What is the function of the SFB pin on the LTC1436AIGN-PLL#PBF?

The SFB (Secondary Feedback) pin on the LTC1436AIGN-PLL#PBF forces continuous conduction mode when tied to ground, ensuring regulation stability in flyback-derived auxiliary supplies. When connected to a resistive divider from a transformer secondary winding, it enables independent regulation of an auxiliary output. In single-output configurations, tying SFB to INTVCC disables its function. This behavior is confirmed in the Applications Information section and functional diagram of the LTC1436AIGN-PLL#PBF datasheet.

Does the LTC1436AIGN-PLL#PBF support external clock synchronization?

Yes, the LTC1436AIGN-PLL#PBF supports external clock synchronization via its dedicated PLLIN pin, which connects to an internal 50 kΩ pull-down resistor. When an external clock signal is applied, the phase-locked loop locks the internal oscillator to the input frequency, with PLL LPF serving as the control voltage node (0–2.4 V range). This capability is exclusive to the -PLL variants and is documented in the Electrical Characteristics and Applications Information sections for LTC1436AIGN-PLL#PBF.

How does the Adaptive Power™ feature improve light-load efficiency in the LTC1436AIGN-PLL#PBF?

The Adaptive Power™ feature in the LTC1436AIGN-PLL#PBF improves light-load efficiency by automatically routing gate drive from the high-current TGL/BG outputs to the lower-capacity TGS output when load drops below ~1% of rated current. This avoids the gate-charge losses inherent in driving large MOSFETs at low duty cycles, sustaining fixed-frequency operation without entering Burst Mode. Verified performance data shows this extends constant-frequency operation down to ~50 mA, reducing audible noise and EMI versus standard Burst Mode controllers.

What is the maximum supported switching frequency for the LTC1436AIGN-PLL#PBF?

The maximum recommended switching frequency for the LTC1436AIGN-PLL#PBF is 400 kHz, as specified in the Applications Information section. While the oscillator can be tuned higher using smaller COSC values, efficiency degrades due to increased MOSFET gate charge losses above this point. The device's ≤300 ns minimum on-time enables practical operation at 400 kHz even for high-input-to-low-output voltage conversions (e.g., 24 V → 1.2 V at 5% duty cycle), making 400 kHz the validated upper limit for reliable design.

Can the LTC1436AIGN-PLL#PBF generate both main and auxiliary regulated outputs simultaneously?

Yes, the LTC1436AIGN-PLL#PBF can generate both main and auxiliary regulated outputs simultaneously: the main synchronous buck output (up to 5 A) is set via VOSENSE/VPROG, while the auxiliary 0.5 A linear regulator is controlled via AUXON, AUXFB, and AUXDR pins. The auxiliary block supports either 12 V (using internal divider when AUXDR > 9.5 V) or adjustable voltages (via external divider), and operates independently - confirmed in the Auxiliary Linear Regulator section of the LTC1436AIGN-PLL#PBF datasheet.