Analog Devices Inc. LTC3809EMSE-1#TRPBF

Overview

LTC3809EMSE-1#TRPBF from Analog Devices (formerly Linear Technology) is a synchronous step-down DC/DC controller IC that drives external complementary P-channel and N-channel MOSFETs without requiring a current-sense resistor. It operates with a fixed 550kHz switching frequency, supports output voltage tracking (coincident or ratiometric), delivers 0.6V ±1.5% reference accuracy, and enables 100% duty cycle for low-dropout operation in battery-powered systems.

For engineers reviewing the LTC3809EMSE-1#TRPBF datasheet, LTC3809EMSE-1#TRPBF pinout, LTC3809EMSE-1#TRPBF application, or LTC3809EMSE-1#TRPBF equivalent, key selection considerations include its No RSENSE™ architecture, selectable Burst Mode®/pulse-skipping/forced continuous operation via the MODE pin, IPRG-configurable peak current sense threshold (70–223mV), auxiliary winding regulation capability, and thermal performance in the 10-lead MSOP package.

Technical Context

The LTC3809EMSE-1#TRPBF implements a constant-frequency current-mode control architecture using V_DS sensing across the external P-channel high-side MOSFET to eliminate the need for a discrete sense resistor. Its differential current comparator monitors the voltage between VIN and SW pins, with peak current threshold dynamically adjusted by the ITH pin voltage and scaled by duty-cycle-dependent slope compensation.

It integrates dual gate drivers (TG for PMOS, BG for NMOS), internal soft-start (0.74ms ramp), undervoltage lockout (2.25V rising threshold), output overvoltage protection (0.68V at VFB), and three operational modes selected via the MODE pin - Burst Mode® (MODE = VIN), pulse-skipping (MODE = VFB), or forced continuous (MODE = GND). The TRACK/SS pin enables precise output voltage tracking during startup.

Key Specifications

Pinout & Package

Package: 10-lead plastic MSOP (3mm × 3mm footprint, exposed pad), rated for –40°C to +85°C operating temperature, θ_JA = 40°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC3809EDD-1#TRPBF, the LTC3809EMSE-1#TRPBF offers identical control functionality but in an MSOP package better suited for manual assembly and thermal management in moderate-power applications; versus MP2307DN-LF-Z, it provides full external MOSFET control, precision tracking, and higher efficiency at medium-to-high loads - making it appropriate for demanding portable and industrial power systems.

Availability

LTC3809EMSE-1#TRPBF is available at Aetrix Electronics and suitable for portable medical devices, notebook computing platforms, industrial IoT edge nodes, and distributed telecom power systems requiring stable component supply, long-term lifecycle support, and guaranteed parametric performance over –40°C to +85°C.

Supply support for LTC3809EMSE-1#TRPBF 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, serving industrial, automotive, communications, and healthcare markets.

The LTC3809-1 product line was designed specifically for high-efficiency, low-input-voltage synchronous buck conversion in battery-powered and intermediate-bus applications, emphasizing No RSENSE™ operation, flexible tracking, and robust protection features.

FAQ

What is the function of the IPRG pin on the LTC3809EMSE-1#TRPBF?

The IPRG pin on the LTC3809EMSE-1#TRPBF selects the maximum allowable voltage drop (ΔV_SENSE(MAX)) across the external P-channel MOSFET, setting the peak current limit. When floating, it configures 125mV; tied to GND, 85mV; tied to VIN, 204mV. This directly determines the maximum output current capability and must be coordinated with the MOSFET's R_DS(ON) per the equation I_OUT(MAX) = ΔV_SENSE(MAX)/R_DS(ON) – I_RIPPLE/2. The LTC3809EMSE-1#TRPBF uses this setting for both normal regulation and slope-compensated current limiting above 20% duty cycle.

Can the LTC3809EMSE-1#TRPBF operate with a 1.8V input supply?

No, the LTC3809EMSE-1#TRPBF cannot operate with a 1.8V input supply. Its absolute minimum input voltage is 2.75V, and its undervoltage lockout (UVLO) rising threshold is 2.25V. Operation below 2.75V violates the specified operating range and risks improper gate drive, unstable regulation, or failure to start. For sub-2.5V inputs, consider alternative controllers such as the LTC3642 or LT8609S. The LTC3809EMSE-1#TRPBF is optimized for 2.75V–9.8V rails, including single/dual Li-ion and 3.3V/5V intermediate buses.

How does the TRACK/SS pin enable output voltage tracking on the LTC3809EMSE-1#TRPBF?

The TRACK/SS pin on the LTC3809EMSE-1#TRPBF replaces the internal 0.6V reference with the applied voltage during startup, causing V_FB to regulate to that voltage instead. When a resistor divider from an external rail (V_X) connects to TRACK/SS, the LTC3809EMSE-1#TRPBF's output ramps proportionally - enabling coincident tracking if V_X's final value exceeds V_OUT and its divider ratio matches the V_OUT feedback network. This ensures controlled sequencing in multi-rail systems. The LTC3809EMSE-1#TRPBF supports both coincident and ratiometric tracking modes depending on the external divider configuration.

What protection features does the LTC3809EMSE-1#TRPBF include?

The LTC3809EMSE-1#TRPBF includes overvoltage protection (OVP) triggered when V_FB exceeds 0.68V (13.33% above 0.6V reference), short-circuit current limiting via the bottom NMOS V_DS comparator (ΔV_SC(MAX) = 60/90/150mV depending on IPRG), undervoltage lockout (UVLO) disabling operation below 2.25V, and reverse-current prevention using the RICMP comparator. It also features micropower shutdown (9μA) and thermal shutdown via junction temperature monitoring. These protections operate independently and do not require external components. The LTC3809EMSE-1#TRPBF integrates all fault detection and response logic internally.

Is the LTC3809EMSE-1#TRPBF pin-compatible with the LTC3809EMSE#TRPBF (non-"-1") version?

No, the LTC3809EMSE-1#TRPBF is not pin-compatible with the non-"-1" LTC3809EMSE#TRPBF. The "-1" suffix denotes a specific variant with different tracking behavior: the LTC3809EMSE-1#TRPBF supports ratiometric tracking (where V_OUT tracks a fraction of V_X), whereas the standard LTC3809EMSE#TRPBF supports only coincident tracking (1:1 ramp). Their pinouts and electrical specifications are identical, but the internal tracking logic differs - substituting one for the other may cause incorrect startup sequencing. Always verify the exact part number and consult the respective datasheet sections on TRACK/SS functionality before replacement. The LTC3809EMSE-1#TRPBF is explicitly characterized for ratiometric use cases.