Analog Devices Inc. LTC3646EMSE-1#PBF

Overview

LTC3646EMSE-1#PBF from Analog Devices (formerly Linear Technology) is a 40V input, 1A synchronous step-down DC/DC converter in a thermally enhanced 16-lead MSOP package. It features ±1% reference accuracy, adjustable 200kHz–3MHz switching frequency, and supports 0.6V–15V output voltage range. Designed for high-voltage intermediate bus conversion, it delivers up to 95% efficiency in Burst Mode operation at light loads while maintaining regulation with only 140µA quiescent current.

For engineers reviewing the LTC3646EMSE-1#PBF datasheet, LTC3646EMSE-1#PBF pinout, LTC3646EMSE-1#PBF application, or LTC3646EMSE-1#PBF equivalent, key selection considerations include its 0.6V–15V output range (LTC3646-1 variant), integrated power FETs, programmable frequency via RT resistor, Burst Mode vs forced continuous mode control, and thermal performance in the MSOP-16 package with exposed PGND pad.

Technical Context

The LTC3646EMSE-1#PBF implements a current-mode, controlled-on-time architecture that maintains constant frequency across wide input-output ratios by dynamically calculating on-time as t_ON = V_ON/(V_IN × f_O). Its valley-current sensing enables precise cycle-by-cycle current limiting at 0.9–1.5A, with negative current detection enabling Burst Mode discontinuous conduction.

It integrates dual N-channel MOSFETs (200mΩ high-side, 120mΩ low-side at 5.5V), a 5.0V internal regulator (INTVCC), and robust protection including input overvoltage lockout (43.5V rising), undervoltage lockout (3.2V falling), and short-circuit current limiting. The MODE/SYNC pin provides direct control of operating mode and external clock synchronization capability.

Key Specifications

Pinout & Package

Package: 16-Lead Plastic MSOP (MSE), 4mm × 3mm body, exposed thermal pad (Pin 17) connected to PGND. Requires soldering of exposed pad for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT8610EMSE#PBF and TPS54202DRCT, the LTC3646EMSE-1#PBF uniquely combines 40V input rating, 0.6V–15V output flexibility, 140µA Burst Mode IQ, and MSOP thermal performance - making it the only choice for space-constrained, high-input-voltage, ultra-low-quiescent applications requiring sub-1V core supplies.

Availability

LTC3646EMSE-1#PBF is available at Aetrix Electronics and suitable for automotive infotainment, industrial PLC I/O modules, and portable medical monitors requiring stable component supply with guaranteed long-term availability and full temperature-grade support.

Supply support for LTC3646EMSE-1#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving aerospace, industrial, automotive, and communications markets.

The LTC3646 family was designed specifically for high-input-voltage, high-efficiency point-of-load conversion in space-constrained environments - emphasizing low quiescent current, wide output adjustability, and robust fault protection for mission-critical systems.

FAQ

What is the minimum output voltage supported by the LTC3646EMSE-1#PBF?

The LTC3646EMSE-1#PBF supports a minimum output voltage of 0.6V, enabled by its precise 0.6V internal reference and ±1% accuracy over –40°C to 85°C. This makes the LTC3646EMSE-1#PBF suitable for powering modern low-voltage processor cores and ASICs requiring tightly regulated sub-1V supplies without external reference components.

How does the LTC3646EMSE-1#PBF achieve high efficiency at light loads?

The LTC3646EMSE-1#PBF achieves high light-load efficiency through Burst Mode® operation, which reduces quiescent current to 140µA typical by disabling both power switches and entering a low-power sleep state while maintaining output regulation via the output capacitor. This behavior is confirmed in the datasheet's efficiency curves and electrical characteristics table under "IQ Sleep Mode".

Can the LTC3646EMSE-1#PBF be synchronized to an external clock?

Yes, the LTC3646EMSE-1#PBF can be synchronized to an external clock applied to the MODE/SYNC pin. When driven with a clock signal between 0.2MHz and 3.0MHz, the part adjusts its top-switch on-time to match the external frequency and operates in forced continuous mode. An RT resistor must still be connected to set the internal oscillator's target frequency.

What is the thermal performance of the LTC3646EMSE-1#PBF in its MSOP package?

The LTC3646EMSE-1#PBF in the 16-lead MSOP (MSE) package has a junction-to-ambient thermal resistance (θ_JA) of 38°C/W when mounted on a standard 2-layer PCB with the exposed PGND pad fully soldered to a 1-in² copper area. This enables full 1A output at 85°C ambient without forced airflow, as verified in the Absolute Maximum Ratings and Package Description tables.

Does the LTC3646EMSE-1#PBF require external compensation components?

The LTC3646EMSE-1#PBF supports both internal and external compensation. Connecting the ITH pin to INTVCC enables default internal compensation for basic applications, while connecting an RC network between ITH and SGND allows full loop optimization for demanding transient response or specific EMI requirements - as detailed in the Pin Functions and Applications Information sections.