Analog Devices Inc. LT8365EMSE#PBF

Overview

LT8365EMSE#PBF from Analog Devices is a current-mode DC/DC converter IC with a 1.5A, 150V internal power switch, supporting boost, SEPIC, and inverting topologies across a 2.8V–60V input range. It delivers ultralow 9µA quiescent current in Burst Mode, maintains <15mV output ripple, and operates up to 500kHz-enabling high-voltage negative outputs (e.g., –250V) for medical imaging and industrial bias supplies.

For engineers reviewing the LT8365EMSE#PBF datasheet, LT8365EMSE#PBF pinout, LT8365EMSE#PBF application, or LT8365EMSE#PBF equivalent, key selection considerations include its single FBX pin enabling both positive/negative output programming, BIAS pin for efficiency optimization, spread-spectrum EMI reduction, and AEC-Q100 qualification for automotive-grade reliability.

Technical Context

The LT8365EMSE#PBF employs fixed-frequency current-mode control with programmable switching frequency (100–500kHz) via an external RT resistor and supports five SYNC/MODE configurations-including Burst Mode (9µA IQ), pulse-skipping, external clock synchronization, and spread-spectrum modulation. Its dual-regulation architecture uses ±1.6V/–0.8V internal references on the FBX pin to support both boost/SEPIC (positive VOUT) and inverting (negative VOUT) operation without topology change.

Thermal performance is enhanced by a thermally optimized 16-lead MSOP package with exposed PGND/GND pad (θJC = 10°C/W), while protection features include overcurrent shutdown (>3A), INTVCC UVLO (2.5V), thermal lockout (>170°C), and programmable soft-start. The BIAS pin enables efficient INTVCC sourcing when 4.4V ≤ BIAS ≤ VIN, reducing VIN load and improving full-load efficiency.

Key Specifications

Pinout & Package

The LT8365EMSE#PBF is housed in a thermally enhanced 16-lead MSOP package (MSE16 variation) with four pins removed (pins 2, 4, 13, 15) to increase high-voltage spacing. The exposed pad (Pin 17) is connected to PGND/GND and must be soldered to a PCB ground plane for thermal and electrical integrity (θJA = 45°C/W, θJC = 10°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar DC/DC controller applications.

Compared with LTC3789EMSE#PBF and LT8330EMSE#PBF, the LT8365EMSE#PBF uniquely combines integrated 150V switching, single-pin polarity selection, 9µA Burst Mode, and AEC-Q100 qualification - making it the only option for compact, high-reliability, high-voltage inverting supplies in medical and automotive systems.

Availability

LT8365EMSE#PBF is available at Aetrix Electronics and suitable for medical diagnostic equipment, automotive ADAS modules, and industrial telecom interfaces requiring stable component supply with guaranteed long-term availability and traceable sourcing.

Supply support for LT8365EMSE#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, industrial automation, and automotive safety markets since 1965.

The LT8365EMSE#PBF belongs to Analog Devices' Power by Linear™ family of high-voltage DC/DC controllers, designed specifically for demanding applications requiring wide input range, ultralow IQ, and robust high-voltage operation in harsh environments.

FAQ

What is the maximum output voltage achievable with the LT8365EMSE#PBF in inverting configuration?

The LT8365EMSE#PBF supports inverting operation with a 150V-rated internal switch and has been validated in typical applications delivering –250V at 10mA. While the absolute maximum switch voltage is 150V, the actual achievable output depends on external components (diode, transformer, layout). For –250V output, the switch sees ~250V plus diode drop during off-time - requiring careful selection of ultra-high-voltage diodes (e.g., DFLS1150) and conservative layout. The LT8365EMSE#PBF itself does not limit output voltage beyond its 150V switch rating; system-level insulation and component ratings govern final VOUT.

Can the LT8365EMSE#PBF operate without the BIAS pin connected?

Yes, the LT8365EMSE#PBF operates fully functional with the BIAS pin tied to GND. In this configuration, the INTVCC regulator draws all current from VIN, resulting in slightly lower full-load efficiency. The BIAS pin is optional: it improves efficiency only when a second supply (4.4V ≤ BIAS ≤ VIN) is available - such as VOUT in SEPIC designs. Leaving BIAS unconnected or floating is not allowed; per the datasheet, unused BIAS must be grounded to prevent instability or undefined behavior. The LT8365EMSE#PBF's core functionality remains intact without BIAS, but efficiency gains up to 3% at full load are forfeited.

How does the LT8365EMSE#PBF achieve 9µA quiescent current in Burst Mode?

The LT8365EMSE#PBF achieves 9µA quiescent current by entering deep sleep between output pulses: during light loads, it delivers a single small energy packet to the output capacitor, then shuts down most internal circuitry (oscillator, error amplifier, gate driver) while retaining regulation awareness via the FBX pin. Only essential bias currents remain active. This architecture minimizes VIN current draw while maintaining output voltage within ±1% and ripple <15mV. The 9µA value is measured at VIN = 12V, VOUT = 24V, and zero load - and is guaranteed over temperature. The LT8365EMSE#PBF's dedicated Burst Mode logic, not just low-leakage design, enables this performance without compromising startup time or regulation accuracy.

Is the LT8365EMSE#PBF pin-compatible with other members of the LT836x family?

No, the LT8365EMSE#PBF is not pin-compatible with LT8361, LT8362, or LT8364. Although all share the same 16-lead MSOP package outline and high-voltage pin spacing, pin functions differ significantly - notably, the LT8365EMSE#PBF uses a single FBX pin for both positive and negative regulation, while earlier variants use separate FB and COMP pins. Additionally, the SYNC/MODE pin behavior, BIAS pin functionality, and internal reference voltages are unique to the LT8365EMSE#PBF. Substituting any other LT836x part requires full schematic and layout revision. The LT8365EMSE#PBF is a distinct product with no mechanical or electrical interchangeability within the family.

Does the LT8365EMSE#PBF support synchronization to external clocks above 500kHz?

No, the LT8365EMSE#PBF supports external clock synchronization only within the 100kHz–500kHz range, matching its programmable internal oscillator range. When driven by an external clock outside this band - for example, 600kHz - the LT8365EMSE#PBF will not lock and may exhibit erratic switching, increased jitter, or failure to regulate. The datasheet specifies fSYNC/fOSC ratio limits of 0.95–1.25, meaning the external clock must be within ±25% of the RT-set frequency. To synchronize reliably, the RT resistor must be selected so that the internal fSW falls within the intended sync frequency window. Attempting sync above 500kHz violates the device's timing architecture and is not supported for the LT8365EMSE#PBF.